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Lesson Explainer: Effects of Temperature and Concentration on Rates of Reactions Science • Third Year of Preparatory School

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In this explainer, we will learn how to describe and explain the effect temperature and concentration have on the rate of chemical reactions.

The speed at which a chemical reaction takes place is known as the rate of reaction. Usually, the rate of reaction describes how some variable changes over a certain period of time. A common way to measure the rate of a chemical reaction is to measure how the concentrations of the reactants and products change over a certain period of time.

Definition: Rate of Reaction

  • The rate of reaction measures how reactant or product concentrations change per unit time.

The rate of a chemical reaction can be affected by many factors. By changing some of these factors, the rate of reaction can be increased or decreased.

The factors that affect the rate of reaction include surface area, temperature, concentration, and the addition of catalysts. We will focus on temperature and concentration.

In order for two particles to react, they must first collide. In addition, the particles must have a certain amount of energy when they collide.

Any factor that can increase the frequency of collisions, or the energy of the particles, will likely increase the rate of reaction.

Example 1: Identifying in Which Box of Particles the Number of Collisions Will Be Greatest

The boxes below represent a chemical reaction between the red and the blue particles. In which box will the number of collisions be greatest?

A chemical reaction occurs when reactants collide with each other. The greater the number of collisions that occur, the more likely the reaction to happen and the faster the rate of reaction.

There are several factors that can affect the rate of reaction. However, from the question and diagram, we can see that we are given four boxes each containing different numbers of particles. The size of the box is also the same in each case.

If the particles are moving randomly, then the more particles there are, the more collisions there are likely to be.

We can see from the diagram that box A contains the greatest number of particles. Therefore, the number of collisions is likely to be greatest in box A.

The answer is box A.

One way to increase the number of collisions is by increasing the temperature. As the temperature increases, the particles gain energy and move faster. The faster the particles move, the more likely they are to collide with each other.

In the diagram below, the larger the arrow, the faster the particle is moving. At higher temperatures, the particles have more energy and so a larger arrow.

The effect of temperature on the rate of reaction can easily be demonstrated in a laboratory experiment. In this experiment, one effervescent tablet is put into a flask that contains hot water and a second tablet is put into a different flask that contains cold water.

The tablet reacts with the water to produce carbon dioxide gas. The experimental setup is shown below.

By measuring the volume of gas produced in each experiment, the rates of reaction can be determined and compared.

The results of this experiment are shown in the graph below:

At the higher temperature, the particles have more energy and move around faster. This increases the number of collisions between particles and increases the rate of reaction.

A faster rate of reaction increases the volume of gas produced at the start of the reaction, resulting in a steeper line on the graph. However, as the mass of the tablet and volume of water remain constant, the final amount of gas produced is the same.

Example 2: Relating Temperature to the Frequency of Collisions between Molecules

The boxes below each contain an equal number of reactant molecules. The boxes are heated to different temperatures. Which box will have the greatest frequency of collisions between molecules?

In order for two reactant molecules to react, they have to collide. There are several factors that can increase the number of collisions between reactant molecules. One of these is temperature.

We are told that each box contains the same number of reactant molecules, so the frequency of collisions is not going to be affected by a different number of molecules. However, the temperature of each box is different, and so, the main effect on the frequency of collisions will be the change in temperature.

As the temperature increases, the reactant molecules gain energy and move faster. The faster the molecules are moving, the more likely they are to collide and the greater the frequency of collisions will be.

The higher the temperature, the greater the frequency of collisions between molecules. Looking at the diagram, we can see that the box with the highest temperature is box D. Therefore, the answer is box D.

Temperature is a very important factor for controlling the rate of reactions in food. Placing food in a cool place, such as a refrigerator or freezer, slows down the chemical reactions that spoil food. As a result, food can be preserved and last longer.

High temperatures are often used when cooking food. The higher temperature increases the rate of reaction and helps cook food quicker and more thoroughly.

The effect of concentration on the rate of reaction can be explained by looking at the frequency of collisions.

Consider the reaction between the purple particles A and the green particles B shown in the diagram below.

If the concentration of B is increased, then the number of particles of B present increases. This is shown in the diagram below.

An increase in the number of particles will result in an increase in the number of collisions. A greater number of collisions causes an increase in the rate of reaction.

The effect of concentration on the rate of reaction can be demonstrated using the reaction of iron wool and oxygen.

Iron wool, also known as steel wool, can be burned in the presence of oxygen. However, the speed and intensity of this reaction changes when the concentration of oxygen changes.

When burned over a Bunsen burner, the iron wool is being burned in air. Air contains 2 1 % of oxygen, a medium to low concentration. The rate of reaction is quite low, and the iron wool burns relatively slowly.

However, when burned in pure oxygen the reaction is much more rapid and intense. The concentration of pure oxygen is ∼ 1 0 0 % , much greater than air. The increase in oxygen concentration increases the rate of reaction and results in a more vigorous and fast reaction.

These two experiments are shown in the image below.

Example 3: Explaining the Different Rates of Combustion in Air Compared with Pure Oxygen

Why is the combustion of aluminum in air slower than in pure oxygen?

  • The temperature of oxygen in air is greater than in pure oxygen.
  • The temperature of pure oxygen is greater than air.
  • The concentration of oxygen in air is less than in pure oxygen.
  • The concentration of oxygen in air is greater than in pure oxygen.

The process of combustion usually refers to the reaction of a substance with oxygen. Here, aluminum is reacted with oxygen under two different conditions.

The combustion of aluminum in air is most likely performed using a Bunsen burner. Air usually contains around 2 1 % oxygen, a relatively low amount of oxygen.

The combustion of aluminum with pure oxygen most likely involves conditions where there is ∼ 1 0 0 % oxygen. We can see that the difference between burning in air and in pure oxygen is the amount, or concentration, of oxygen present.

From this, we can conclude that the difference in the rate of combustion is because of the different concentrations of oxygen. Our answer is therefore likely to be either C or D.

Concentration can affect the rate of reaction by changing the number of reactant molecules present. The more reactant molecules there are, the greater the number of collisions that will occur between them and the faster the rate of reaction is.

As concentration increases, the rate of reaction increases.

The combustion of aluminum in air is slower because the concentration of oxygen is lower than in pure oxygen. This statement matches with choice C, and so our answer is C.

Another experiment that shows the effect of concentration on the rate of reaction is the reaction of magnesium with hydrochloric acid.

In this experiment, one conical flask contains dilute hydrochloric acid and a different flask contains concentrated hydrochloric acid. Into each conical flask is placed an identical piece of magnesium of the same size and mass.

The chemical equation for the reaction between magnesium and hydrochloric acid is M g ( ) + 2 H C l ( ) M g C l ( ) + H ( ) s a q a q g 2 2

Therefore, by measuring the volume of hydrogen gas produced over time, any change in the rate of reaction can be determined.

The setup of this experiment is shown in the image below:

By plotting a graph of the volume of hydrogen gas produced against time, the rates of reaction for each experiment can be determined. A graph showing the rate of reaction for dilute and concentrated hydrochloric acid is shown below:

The graph shows that a greater volume of hydrogen gas is produced over a short period of time when concentrated hydrochloric acid is used. This shows that the rate of reaction increases as the concentration increases.

As the concentration of hydrochloric acid increases, the number of acid particles present increases. As a result, there is a greater number of collisions between the acid and the magnesium particles, and so, there is an increase in the rate of reaction.

Example 4: Ordering Experiments with Differing Concentration by Their Rate of Reaction

A chemist performs a series of experiments to determine the effect of concentration on the rate of a reaction. They pour an equal amount of hydrochloric acid of different concentrations into four test tubes, then they place an identical piece of magnesium ribbon into each of the test tubes. The experiment setup is shown below.

From slowest to quickest, what is the likely ordering of the rate of reaction for the four experiments?

There are several factors that can affect the rate of reaction. These include concentration and surface area. In the experiment, the volume of hydrochloric acid used is kept the same. An identical piece of magnesium is also used, and so, the surface area and mass are kept the same.

The only factor that is changing is the concentration of hydrochloric acid. The concentration is greatest for experiment D and lowest in experiment B.

For a reaction to occur, the reactant molecules must collide with each other. Increasing the number of collisions increases the rate of reaction.

When the concentration is increased, the number of acid particles present in the solution increases. The increased number of acid particles will result in a greater number of collisions and therefore a faster rate of reaction.

If the rate of reaction increases as the concentration increases, then the order of the rate reaction from slowest to quickest will correspond to the order from the lowest to the greatest concentration.

From slowest to quickest, the likely ordering is B, C, A, D, which corresponds to answer choice D. The correct answer is therefore D.

Example 5: Identifying Which Set of Conditions Gives the Greatest Rate of Reaction

In a series of experiments, a student changes both the concentration and the temperature. The conditions for each experiment are shown below. In which conical flask is the rate of reaction likely to be highest?

The rate of a reaction is affected by both temperature and concentration. For a reaction to occur, reactant particles must collide with each other. Any factor that increases the number of collisions is likely to increase the rate of reaction.

As the temperature increases, the particles are given more energy and can move faster. As a result, there is likely to be a greater number of collisions and a faster rate of reaction. Therefore, the rate of reaction increases as the temperature increases.

As the concentration increases, the number of reactant particles increases. With a greater number of particles present, there is likely to be a greater number of collisions and a faster rate of reaction. Therefore, the rate of reaction increases as the concentration increases.

From the two statements above, we can conclude that the rate of reaction is likely to be highest when both the temperature and the concentration are greatest.

In the diagram above, we can see that the highest temperature is 5 0 ∘ C and the highest concentration is 2 mol/L , which occurs in experiment C.

The rate of reaction is therefore likely to be highest for experiment C.

  • For a chemical reaction to occur, reactant particles must collide with each other.
  • Generally, as the number of collisions between reactant particles increases, the rate of reaction increases.
  • When the temperature increases, the particles gain more energy and the number of collisions increases, causing the rate of reaction to increase.
  • The effect of temperature on the rate of reaction can be seen experimentally by reacting effervescent tablets with water and measuring the volume of gas produced.
  • Increasing the concentration increases the number of particles present. There is a greater number of collisions, and so, the rate of reaction increases.
  • The combustion of substances such as iron wool in pure oxygen is faster than in air because the concentration of oxygen is lower in air.
  • The effect of concentration on the rate of reaction can be seen experimentally by reacting magnesium with different concentrations of hydrochloric acid and measuring the volume of gas produced.

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concentration effect on rate of reaction experiment

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Core Chemistry 14 - 16

Particles can only react if they collide - and they not only have to collide, but must collide with enough energy for something to happen, and may need to collide the right way round if the particle is a more complicated shape than a single atom or ion.

Increasing the concentration simply means that the particles are going to hit each other more often.

A simple quick experiment

Take the reaction between marble chips and dilute hydrochloric acid, for example.

CaCO (s) + 2HCl(aq)  (aq) + CO (g) + H O(l)

If you do this with small marble chips and ordinary bench dilute hydrochloric acid, you get a good supply of bubbles of carbon dioxide produced.

If you dilute the hydrochloric acid by a factor of 10, the reaction is much less vigorous and the flow of carbon dioxide is much slower.

In fact, you will also only get a tenth of the volume of carbon dioxide produced if you collect it all. The marble chips are likely to be in large excess, and the amount of carbon dioxide produced is limited by the amount of acid.
A more detailed experiment

A commonly used experiment to show the effect of concentration on rate is between dilute hydrochloric acid and sodium thiosulfate solution.

Na S O (aq) + 2HCl(aq)  (g) + S(s) + H O(l)

At this stage, the only place you are likely to come across sodium thiosulfate is in this reaction.

The interesting thing about the reaction is the formation of a precipitate of sulfur. This is formed slowly and appears first as a very pale cream solid which turns yellow as more of it is formed.

In the video you are going to watch, the time taken to form a very small fixed amount of sulfur is measured at various concentrations of sodium thiosulfate, keeping everything else the same.

As you will see, the more dilute the sodium thiosulfate, the longer the time it takes for that amount of sulfur to form.

The is the one that changes as a result of something you are doing. In this case, the dependent variable is the time taken for the cross to disappear, because that is changing as a result of you changing the concentration.

The is the one that you are changing - in this case, the concentration.

The independent variable is always plotted on the x-axis, and the dependent one on the y-axis. The video showed a graph of the results of time taken against concentration and looked like this.

As it stands, this isn't actually very helpful. All it shows is that as you increase the concentration, the time taken for the cross to disappear gets less. But you can see that just by looking at it.

It would be much better if we could find a more precise relationship between the rate of the reaction and the concentration.

If you have read the page about the effect of on rates of reaction, you will have read about "initial rate" experiments. This is another initial rate experiment.

You are finding the time taken for a very small amount of sulfur to be produced at the very beginning of the reaction as you vary concentration.

If you could do a complete plot of the mass of sulfur being formed against time, you would get a curve starting steeply, slowing down, and then stopping - exactly like the one you saw on the previous page.

But at the very beginning of the reaction, the curve is almost a straight line. So if you consider plots of the very early parts of three reactions to produce a fixed mass of sulfur in this experiment, the graphs would look like this.

The initial rates would be m/t , m/t and m/t grams of sulfur per second.

You don't know what m is of course - that would depend, amongst other things, on how thick your cross was, and how good your eyesight is. But it is always going to be the same in every experiment.

What you can say is that the initial rate is proportional to 1/t - or inversely proportional to t, if you prefer.

If it takes half as long for the cross to disappear, the rate is twice as fast; if it takes 4 times as long for the cross to disappear, the rate is only a quarter as fast.

On a graph, we can use this by plotting 1/t as a measure of rate. It isn't an actual rate, but it allows you to compare rates.

Doing this shows that in this reaction, you have a straight line relationship between concentration and rate - rate is proportional to concentration.

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Investigating the Effect of Concentration on Reaction Time

Concentration vs Rate of Reaction

Whether you are introducing collision theory or something more demanding like reaction order, the reaction between sodium thiosulfate—Na 2 S 2 O 3 and hydrochloric acid can provide a consistent, accurate, and engaging opportunity for investigating these topics.

A few weeks ago, I was looking for a new reaction that could be used to investigate how concentration affects reaction time. In the past, I had always used traditional reactions such as magnesium and hydrochloric acid or Alka-Seltzer and hydrochloric acid. Though both served their purpose, there would always be groups that didn’t quite get data that was consistent with what I knew the relationship to be. In most cases, this was due to ambiguous and inconsistent timing methods or simply a matter of experimental error like not ensuring the magnesium stayed in the acid without floating to the top. I wanted a reaction that would be more likely to produce consistent results from group to group, easy to execute, and was a bit more exciting than waiting for magnesium or Alka-Seltzer to disappear.

Eventually, I came across a Flinn 1 experiment which focused on the reaction between sodium thiosulfate and hydrochloric acid.

Na 2 S 2 O 3 (aq) + HCl (aq) → 2NaCl (aq) + S (s) + H 2 O (l) + SO 2 (g)

What I liked most about this reaction was the easy and consistent timing mechanism it provided my students with, which could eliminate the ambiguity and differences in timing approaches that lab groups had used in the past.

Here’s how: As the reaction proceeds, one of the products is sulfur. As more sulfur gets produced, the solution becomes more and more cloudy until eventually the solution is opaque. Because of this, the moment that you can no longer see through the solution can be used as a consistent way to stop time. When I asked my students how we would all consistently decide on when the solution is opaque, many of them suggested to place some sort of object on the other side of the beaker so that we would all stop the timer when the object was no longer visible. This naturally progressed to the idea of drawing something on the beaker itself (an X on the bottom in this case) and applying the same reasoning.

reactions series of beakers with X on bottom

reactions series of beakers with X on bottom

series of beakers after X is blocked

series of beakers after X is blocked

This reaction and the implementation of this natural clock can be seen below in a Flinn video 2 .

Even though it is just a matter of changing from visible to opaque, I noticed that the anticipation of waiting for that X to disappear had nearly all my students hovering over their beakers anxiously waiting to stop their timer. It even got to a point where different groups started to use their phones to make time lapse videos of their reaction beakers. You can see one below. As a teacher, it was fun to watch their level of excitement over something so seemingly simple.

Though I used this experiment to primarily investigate collision theory and different factors that affect the time it takes for a reaction to complete, it could easily be used to determine something more complex like reaction order ( see the entire Flinn video from which the above clip is taken ).

I also found this lab to serve as a great opportunity for my students to play a larger role in the creation of the experimental setup since there wasn’t much complexity to it. I facilitated the design of the experiment by asking my students a series of questions that were meant to feel like it was a genuine conversation happening between scientists interested in answering a question. The PowerPoint that I used to help facilitate this discussion can be found as Supporting Information at the bottom of this post if you are logged in to ChemEd X, but the general theme followed these questions:

  • What is our independent variable? How should we go about changing this?
  • Should the total volume of each beaker be the same or different? Why?
  • What is our dependent variable?
  • Are there any variables that we should control?
  • How should we go about timing our reaction?
  • How should we record and organize our data?
  • How are we going to figure out our concentrations in terms of Molarity?
  • What are we going to do with our data once we have it? Graph it?

I don’t include students in things like this often enough and it’s important that I continue to remind myself the beneficial experience this can provide for students to get a more accurate understanding of how science operates.

However you decide to do it, the general approach to this experiment goes something like this:

1) Using a Sharpie, draw a black X on the bottom (outside) of each beaker. 2) A stock solution of 0.15 M Na 2 S 2 O 3 is used to make 5 different concentrations using different amounts of distilled water, though our tap water worked just fine too. The total volume of each solution should be the same in each beaker. 3) Add 5 mL of 2 M HCl to your first beaker to start the reaction. You can give it an initial stir to uniformly distribute the HCl. The timer starts after this initial swirl. 4) While looking down at the beaker, stop the timer the moment you see the X completely disappear from sight. 5) Do this for all your samples and start analyzing your data

After everyone had finished the experiment and analyzed their results, I was thrilled to see that the data from each group produced a graph that displayed the relationship I was looking for. Not a single group had one weird outlier or a graph with seemingly random points all over the place! Some of the groups even paid close enough attention to the fact that each beaker had different levels of “opaqueness” to them. This provided a great opportunity to talk about the benefits of qualitative evidence as well. I attribute these consistent results to two primary things:

1) Consistent timing mechanism that each group can easily reproduce 2) It is almost impossible to mess up this reaction—you’re just pouring HCl into your Na 2 S 2 O 3 solution. Minimizing chances for experimental error was huge.

Effect of Concentration on Reaction Time Graph

Effect of Concentration on Reaction Time Graph

Though I don’t always shoot for consistent data between groups when we do a lab, I knew that the arguments would vary between groups when trying to explain why their experiment displayed the relationship it did. It is the arguments I am most interested in developing after students complete their data analysis.

concentration effect on rate of reaction experiment

Students were tasked with developing their initial argument using a Claim, Evidence, Reasoning (CER) framework. Though most boards had similar claims, they often differed in what evidence they chose to present. They all had access to the same evidence and yet different groups intentionally left out certain pieces of evidence—why? Where their boards differed the most was in their reasoning, which is meant to have them justify why their evidence makes sense based on known scientific principles. I should mention that the students had not been presented anything about collision theory before this lab and yet many of them were able to come up with a valid particle-based explanation while others either circled around ambiguity, lacked detail, or simply displayed some form of misconception. The important part of this was that they tried their best, based on the models they had running around in their heads, to explain the phenomenon and knew that it was up to the scientific community (our class) to act as a filter for sorting out valid explanations from ones that either lacked detail or could not quite account for the evidence. This is the process I love doing the most.

The lab itself took about 30 mins to do but because I involved them in the experimental setup and dedicated time to construct arguments that were presented, debated, and refined, the entire process took 3 periods (1 hr each).

I want to thank Flinn for inspiring the idea for the experiment in the first place and NSTA’s book Argument-Driven Inquiry in Chemistry 3 for providing the framework we used to set up and make sense of the investigation.

Resources 1 Rate of Reaction of Sodium Thiosulfate and Hydrochloric Acid . N.p.: Flinn Scientific, n.d. Pdf . https://www.flinnsci.com/globalassets/flinn-scientific/all-free-pdfs/dc91860.pdf 2  "Rate of Reaction of Sodium Thiosulfate and Hydrochloric Acid..."20 Dec. 2012, & https://www.youtube.com/watch?v=r4IZDPpN-bk . Accessed 17 Jan. 2017. 3 "NSTA Science Store: Argument-Driven Inquiry in Chemistry: Lab ...." 1 Oct. 2014, https://www.nsta.org/store/product_detail.aspx?id=10.2505/9781938946226 . Accessed 17 Jan. 2017.

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Science Practice: Analyzing and Interpreting Data

Analyzing data in 9–12 builds on K–8 and progresses to introducing more detailed statistical analysis, the comparison of data sets for consistency, and the use of models to generate and analyze data.

Analyzing data in 9–12 builds on K–8 and progresses to introducing more detailed statistical analysis, the comparison of data sets for consistency, and the use of models to generate and analyze data. Analyze data using tools, technologies, and/or models (e.g., computational, mathematical) in order to make valid and reliable scientific claims or determine an optimal design solution.

Science Practice: Asking Questions and Defining Problems

Asking questions and defining problems in grades 9–12 builds from grades K–8 experiences and progresses to formulating, refining, and evaluating empirically testable questions and design problems using models and simulations.

questions that challenge the premise(s) of an argument, the interpretation of a data set, or the suitability of a design.

Scientific questions arise in a variety of ways. They can be driven by curiosity about the world (e.g., Why is the sky blue?). They can be inspired by a model’s or theory’s predictions or by attempts to extend or refine a model or theory (e.g., How does the particle model of matter explain the incompressibility of liquids?). Or they can result from the need to provide better solutions to a problem. For example, the question of why it is impossible to siphon water above a height of 32 feet led Evangelista Torricelli (17th-century inventor of the barometer) to his discoveries about the atmosphere and the identification of a vacuum.

Questions are also important in engineering. Engineers must be able to ask probing questions in order to define an engineering problem. For example, they may ask: What is the need or desire that underlies the problem? What are the criteria (specifications) for a successful solution? What are the constraints? Other questions arise when generating possible solutions: Will this solution meet the design criteria? Can two or more ideas be combined to produce a better solution?

Science Practice: Constructing Explanations and Designing Solutions

Constructing explanations and designing solutions in 9–12 builds on K–8 experiences and progresses to explanations and designs that are supported by multiple and independent student-generated sources of evidence consistent with scientific ideas, principles, and theories.

Constructing explanations and designing solutions in 9–12 builds on K–8 experiences and progresses to explanations and designs that are supported by multiple and independent student-generated sources of evidence consistent with scientific ideas, principles, and theories. Construct and revise an explanation based on valid and reliable evidence obtained from a variety of sources (including students’ own investigations, models, theories, simulations, peer review) and the assumption that theories and laws that describe the natural world operate today as they did in the past and will continue to do so in the future.

Science Practice: Developing and Using Models

Modeling in 9–12 builds on K–8 and progresses to using, synthesizing, and developing models to predict and show relationships among variables between systems and their components in the natural and designed worlds.

Modeling in 9–12 builds on K–8 and progresses to using, synthesizing, and developing models to predict and show relationships among variables between systems and their components in the natural and designed worlds. Use a model to predict the relationships between systems or between components of a system.

Science Practice: Engaging in Argument from Evidence

Science practice: obtaining, evaluating, and communicating information.

Engaging in argument from evidence in 9–12 builds on K–8 experiences and progresses to using appropriate and sufficient evidence and scientific reasoning to defend and critique claims and explanations about natural and designed worlds. Arguments may also come from current scientific or historical episodes in science.

Engaging in argument from evidence in 9–12 builds on K–8 experiences and progresses to using appropriate and sufficient evidence and scientific reasoning to defend and critique claims and explanations about natural and designed worlds. Arguments may also come from current scientific or historical episodes in science. Evaluate the claims, evidence, and reasoning behind currently accepted explanations or solutions to determine the merits of arguments.

Science Practice: Planning and Carrying out Investigations

Planning and carrying out investigations in 9-12 builds on K-8 experiences and progresses to include investigations that provide evidence for and test conceptual, mathematical, physical, and empirical models.

Planning and carrying out investigations in 9-12 builds on K-8 experiences and progresses to include investigations that provide evidence for and test conceptual, mathematical, physical, and empirical models. Plan and conduct an investigation individually and collaboratively to produce data to serve as the basis for evidence, and in the design: decide on types, how much, and accuracy of data needed to produce reliable measurements and consider limitations on the precision of the data (e.g., number of trials, cost, risk, time), and refine the design accordingly.

HS-PS1-5 Rates of Reactions

Students who demonstrate understanding can apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction occurs.

*More information about all DCI for HS-PS1 can be found at  https://www.nextgenscience.org/dci-arrangement/hs-ps1-matter-and-its-interactions and further resources at https://www.nextgenscience.org .

Assessment is limited to simple reactions in which there are only two reactants; evidence from temperature, concentration, and rate data; and qualitative relationships between rate and temperature.

Emphasis is on student reasoning that focuses on the number and energy of collisions between molecules.

All comments must abide by the ChemEd X Comment Policy , are subject to review, and may be edited. Please allow one business day for your comment to be posted, if it is accepted.

Comments 11.

Tracy Schloemer's picture

This is awesome. I found this lab to be very useful too, and appreciate how you've shared how it's run in your classroom.

Ben Meacham's picture

Thanks!  Glad I came across it and was able to reflect/share.  

Bringing Kinetics to First Year Chem

Kaleb Underwood's picture

I thoroughly enjoyed reading your reflections on this activity. I use a microscale version of this reaction in my AP Chemistry class and have students calculate the order of reaction with respect to thiosulfate and hydrochloric acid. It is a very reliable procedure and the students enjoy the lab for the reasons you've discussed.

I usually don't touch on kinetics in my first year course, but this year while I was teaching it I realized that the theory of kinetics (collision theory, activation energy, catalysts, decrease of rate with time) is very accessible to first year students who have a firm grasp of the particulate nature of matter. Thank you for posting how you went through this with them, I plan on giving it a shot in my chemical reactions unit that will now include basic kinetic theory.

Kinetics Question

Thank you for sharing this lab!  I am a new teacher and really appreciate such good resources.

One question: In my textbook (Chemistry by Whitten, Davis, Peck, Stanley), the integrated rate laws use ln [A]0- ln [A]= a kt.  So when working textbook problems, I've had the students use the coefficient in calculations.  However, I noticed in the AP FRQ a is not included (such as 2004B #3) and a is not included in the given equations.  I am confused on what is the correct method and how I should be teaching this.  I would appreciate any clarification.

Integrated Rate Law Question

Hi Beverly, 

I have a coppy of the 10th edition of Whitten (though I do not use it) and it does indeed use " a " for the coefficient from the balanced equation. This is new to me and I have not seen it before. However it makes sense if you look at how they set up the integration compared to other sources.

Method 1: The rate of reaction of a first order reaction A --> Products is defined as Rate = -d[A]/dt = k [A]. This assumes A has a coefficient of 1.

Method 2: The Whitten text defines the same thing, but uses the reaction a A --> Products as the model. This leads to Rate = (1/ a )(-d[A]/dt). This affects the value of k  in Rate = k [A] and the inclusion of  a  in the integrated rate law.

k  (the "rate constant") is simply a proportionality constant, it's value just depends on how you define it. If we say that  k = ak'  then if you're asked to calculate "the rate constant of the reaction" and use Method 1 exclusively then you are solving for k . If you take in to account the stoichiometry, you are solving for k' .

Given the prevelance of not including  a  I would assume that "the rate constant" is widely considered by chemists to be the value obtained via Method 1.

Now for your concerns about practice in AP Chemistry. 

This area of possible confusion have only come up twice to my knowledge. Once in 2008 #3 and once in 2016 #5. In both situations the graders accepted either value for  k . The scoring guidelines for both exams are here:

2008 Scoring Guidelines

2016 Scoring Guidelines

The forumula included on the formula chart, combined with the precedent of these two equations leads me to belive that either method will be accepted unless a more specific question were asked.

I hope this helps. 

Definition of reaction rate

John Moore's picture

As defined by the International Union on Pure and Applied Chemistry, reaction rate depends on stoichiometry. You can find the defnition here: https://goldbook.iupac.org/html/R/R05156.html . So, if the reaction is aA --> products, the rate is defined as -(1/a)(d[A]/dt). This affects the integration, and therefore the integrated rate law, just as Kaleb says.. If the stoichiometry is A --> products, then a does not appear in the integrated rate law but only because a = 1. It appears that the AP folks allowed for both of these possibilities, which seems reasonable to me.

The version with a included is more general and gives the other version when a = 1. The distinction is important when rate constants are reported in a published paper because if the stoichiometric coefficient a is not included the rate constant value will be off by a factor of a. However, the distinction seems a lot less important when students are learning this for the first time.

I did want to clarify that the version with a included is the version that most chemists who do kinetics studies would say is correct.

IUPAC To the Rescue!

Thank you for your response and link to the Gold Book! I am glad to know that the chemistry community does have a a published, accepted standard for this (and that I was incorrect in my assertion). I agree that the distinction seems less imporant for first-time students, I am curious if this is the reasoning of the AP Test Development Committee as well and am going to reach out to see.

Kinetics Response

Hey Beverly, 

I don't teach AP so I don't want to suggest a "correct method" but here's what I'm thinking based on my own limited knowledge of integrated rate laws.  

The short answer: I don't think the coefficient ( a ) is necessary.  

Why I think  a  isn't necessary: I think your answer can be found in the difference between differential rate laws and integrated rate laws--at least it helped me understand it better.  Resource  here

Differential rate laws express the rate of reaction as a function of a change in the concentration of one or more reactants over a particular period of time, they are used to describe what is happening at the molecular level during a reaction (mechanism-focused).  

On the other hand, integrated rate laws express the reaction rate as a function of the intial concentration and a measured (actual) concentration of one or more reactants after a sepcific amount of time has passed--they are used to determine the rate constant and the reaction order from experimental data.

To me, that means that because the order of a reaction is determined experimentally, they do not represent the coefficients from a balanced equation like they would for an equilibrium expression.  In other words, the expression used for a rate law generally bears no relation to the reaction equation, and must be determined experimentally (Resource  here )

I hope that helped somewhat.  There are several people on this site that would be most likely provide a much easier answer so I can reach out to others if this didn't help.  If nothing else, I got to brush up on topics I haven't dealt with for some time! 

sodium thiosulfate pentahydrate

I checked my chemical inventory and found that I only have the hydrate. Do you think it would work?

Hydrate Will Work

It will work. Just make sure you account for the added mass from water when making your solutions of desired concentration.

Disappearing X

Dan Meyers's picture

Great minds think alike. I posted a video post about 1.5 weeks before on this same topic.

https://www.chemedx.org/blog/disappearing-x-lab

I plan on reading your post more in depth tonight during conferences if time allows. I don't do much modeling or CER although more of this may show up as we revamp our chemistry 1 curriculum to comply with our updated state science standards.

Investigating The Rate of a Reaction ( CIE IGCSE Chemistry )

Revision note.

Alexandra

Investigating the rate of a reaction

  • How quickly the reactants are used up OR How quickly the products are formed
  • The method used for measuring depends on the substances involved
  • They all depend on a property changing during the course of the reaction
  • The changing property is taken to be proportional to the concentration of the reactant or product
  • This can be done by averaging a collected measurement over the course of the reaction
  • Some reaction rates can be measured as the reaction proceeds (this generates more data)
  • measuring mass loss on a balance
  • measuring the volume of a gas produced
  • measuring a reaction where there is a colour change at the end of the reaction

Investigating the effect of concentration of a solution on the rate of reaction

Investigating the effect of concentration on rate of reaction

Diagram showing the apparatus needed to investigate the effect of concentration on the rate of reaction

  • Measure 50 cm 3 of sodium thiosulfate solution into a flask
  • Measure 5 cm 3 of dilute hydrochloric acid into a measuring cylinder
  • Draw a cross on a piece of paper and put it underneath the flask
  • Add the acid into the flask and immediately start the stopwatch
  • Look down at the cross from above and stop the stopwatch when the cross can no longer be seen
  • Repeat using different concentrations of sodium thiosulfate solution (mix different volumes of sodium thiosulfate solution with water to dilute it)
  • With an increase in the concentration of a solution, the rate of reaction will increase
  • This is because there will be more reactant particles in a given volume, allowing more frequent and successful collisions, increasing the rate of reaction

Investigating the effect of surface area on the rate of reaction 

Investigating the effect of surface area on rate of reaction

Diagram showing the process of downwards displacement to investigate the effect of the surface area of a solid on the rate of reaction

  • Add dilute hydrochloric acid into a conical flask
  • Use a delivery tube to connect this flask to a measuring cylinder upside down in a bucket of water (downwards displacement)
  • Add magnesium ribbon to the conical flask and quickly put the bung back into the flask
  • Measure the volume of gas produced in a fixed time using the measuring cylinder
  • The same total mass of magnesium must be used 
  • Smaller pieces of magnesium ribbon cause an increase in the surface area of the solid, so the rate of reaction will increase
  • This is because more surface area of the particles will be exposed to the other reactant so there will be more frequent and successful collisions, increasing the rate of reaction

Investigating the effect of temperature on the rate of reaction

Investigating the effect of temperature on rate of reaction

Diagram showing the apparatus needed to investigate the effect of temperature on the rate of reaction

  • Dilute hydrochloric acid is heated to a set temperature using a water bath
  • Add the dilute hydrochloric acid into a conical flask
  • Add a strip of magnesium and start the stopwatch
  • Stop the time when the magnesium fully reacts and disappears
  • Repeat at different temperatures and compare results
  • With an increase in the temperature, the rate of reaction will increase
  • This is because the particles will have more kinetic energy than the required activation energy, therefore more frequent and successful collisions will occur, increasing the rate of reaction

Investigating the effect of a catalyst on the rate of reaction

Investigating the effect of a catalyst on rate of reaction

Diagram showing the apparatus needed to investigate the effect of a catalyst on the rate of reaction

  • Add hydrogen peroxide into a conical flask
  • Use a delivery tube to connect this flask to a measuring cylinder upside down in a tub of water (downwards displacement)
  • Add the catalyst manganese(IV) oxide into the conical flask and quickly place the bung into the flask
  • Repeat experiment without the catalyst of manganese(IV) oxide and compare results
  • Using a catalyst will increase the rate of reaction
  • The catalyst will provide an alternative pathway requiring lower activation energy so more colliding particles will have the necessary activation energy to react
  • This will allow more frequent and successful collisions, increasing the rate of reaction

Monitoring changes in mass

  • Many reactions involve the production of a gas which will be released during the reaction
  • The gas can be collected and the volume of gas monitored as per some methods above
  • Alternatively, the reaction can be performed in an  open flask   on a balance to measure the loss in mass of reactant
  • Cotton wool is usually placed in the mouth of the flask which allows gas out but prevents any materials from being ejected from the flask (if the reaction is vigorous)

Measuring the mass lost during a chemical reaction

Diagram showing the set-up for measuring the rate of reaction by loss in mass

  • This method is not suitable for hydrogen and other gases with a small relative formula mass,  M r   as the loss in mass may be too small to measure

There are many different methods of investigating the rate of reaction.

Another method of gas collection you may see uses a gas syringe.

Extended tier students may be required to devise and evaluate methods of investigating rates of reaction.

Evaluating investigations of rates of reactions

Extended tier only

  • When investigating rates of reaction, there are a number of different methods that can be used to carry out the same investigation
  • Evaluating what is the best method to use is part of good experimental planning and design
  • This means appreciating some of the advantages and disadvantages of the methods available

Advantages and disadvantages of methods of investigating rates of reaction

Formation of a solid / precipitate

(Disappearing cross experiment)

Simple experiment with no specialist equipment

Difficult to determine when the cross is obscured as people will determine the cross to have disappeared at different levels of cloudiness

Easy to contaminate equipment

Gas collection using a gas syringe

Works for all reactions that produce a gas

All the gas collected is from the reaction

Easy to set up

Gas syringes are fragile and expensive

Gas syringes can stick

They can collect limited volumes

Gas is lost while the bung is connected to the reaction flask

Gas collection using an inverted measuring cylinder

Works for all reactions that produce a gas

Uses common lab equipment

The delivery tube can pop out of the measuring cylinder

It can be difficult to read the scale as it is upside down and may be obscured by bubbles

Gas is lost while the bung is connected to the reaction flask

Measuring mass lost on a balance

Easy to set up

Uses common lab equipment

Not suitable for gases with low molecular mass

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Alex studied Biochemistry at Newcastle University before embarking upon a career in teaching. With nearly 10 years of teaching experience, Alex has had several roles including Chemistry/Science Teacher, Head of Science and Examiner for AQA and Edexcel. Alex’s passion for creating engaging content that enables students to succeed in exams drove her to pursue a career outside of the classroom at SME.

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Three cartoons: a female student thinking about concentration, a male student in a wheelchair reading Frankenstein and a female student wearing a headscarf and safety goggles heating a test tube on a bunsen burner. All are wearing school uniform.

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How to teach rate experiments

David Everett

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David Everett discusses ideas for enhancing practical work on rates of reaction

Why study rates?

The study of reaction kinetics leads to an understanding of a reaction’s mechanism and how we can control the reaction rate. For a 14-year-old student the above question is more likely to be ‘Why are we doing this?’ or ‘What’s it got to do with me?’.

If we are to communicate rates to pupils, they must be engaged with experiments and material that has some relevance to their everyday experiences. I have often wondered how students can ever be engaged with dissolving marble chips in dilute hydrochloric acid. When was the last time, if ever, the average student has come across marble chips in everyday life?

Underpinning chemistry and progression

Flow diagram - The progression of ideas about rates in pre-16 chemistry

Source: Royal Society of Chemistry

The progression of ideas about rates in pre-16 chemistry

The study of rates is fundamental to a student’s understanding of chemical reactions. Students encounter the idea that reactions are the result of the rearrangement of particles into new substances and that mass is conserved during a reaction. It is important this concept is fully understood as it leads naturally to an understanding of why altering conditions will alter the reaction rate. At a higher level, students will explain these effects in terms of the frequency of collisions between particles and the energy profile of those particles.

Developing practical skills and progression

Observation skills are at the core of practical work and these skills are developed as students progress through a range of experiments. Some of the difficulties encountered in making observations were discussed in an earlier article (rsc.li/2gMEM7v). In rate experiments, students need to make a judgement about the ‘end point’ when timing a reaction. In some cases this is sharp and obvious. However, in the reaction between sodium thiosulfate and acid, students must judge when the mixture becomes opaque. Students need to practice through a range of experiments if they are to develop this skill.

Observation skills are at the core of practical work and these skills are developed as students progress through a range of experiments. Some of the difficulties encountered in making observations were discussed in an earlier article . In rate experiments, students need to make a judgement about the ‘end point’ when timing a reaction. In some cases this is sharp and obvious. However, in the reaction between sodium thiosulfate and acid, students must judge when the mixture becomes opaque. Students need to practice through a range of experiments if they are to develop this skill.

Measuring skills are central to rate experiments. Collecting gases is particularly problematic – many students find inverting measuring cylinders hard without inadvertently introducing air or fail to collect all the gas generated in the experiment. Again their manipulative skills can only be developed by practising a range of experiments.

Timing reactions is an area where students need to make sophisticated judgements, not only about when the end point of the reaction is reached, but also about the precision of their measurements. The use of digital stopclocks, apparently measuring to milliseconds, is at odds with their ability to stop the device. An analogue stopclock may reduce the likelihood of students recording unrealistic divisions of seconds, but pupils need to develop their judgement about how precisely times are recorded.

Once students have recorded data from experiments, they need to analyse it and translate it into a form that can be readily understood. Drawing appropriate graphs and using them to find a pattern of behaviour is the goal. However, students need help to develop this skill. They may need to be told which axes are appropriate until they can identify the independent and dependent variables. In many reactions students will need to find the gradient of a graph and interpret this in terms of the rate of the reaction. This was discussed in some detail in an earlier article (rsc.li/2D8sIqI).

Once students have recorded data from experiments, they need to analyse it and translate it into a form that can be readily understood. Drawing appropriate graphs and using them to find a pattern of behaviour is the goal. However, students need help to develop this skill. They may need to be told which axes are appropriate until they can identify the independent and dependent variables. In many reactions students will need to find the gradient of a graph and interpret this in terms of the rate of the reaction. This was discussed in some detail in an earlier article .

Practical work required by GCSE specifications

 

AQA GCSE Chemistry (8462)

Investigate how changes in concentration affect the rates of reactions by a method involving measuring the volume of a gas produced and a method involving a change in colour or turbidity. This should be an investigation involving developing a hypothesis.

Edexcel GCSE (9–1) Chemistry

Investigate the effects of changing the conditions of a reaction on the rates of chemical reactions by:

a) measuring the production of a gas (in the reaction between hydrochloric acid and marble chips)

b) observing a colour change (in the reaction between sodium thiosulfate and hydrochloric acid)

OCR GCSE (9–1) Gateway Chemistry A

and

OCR GCSE (9–1) Twenty First Century Science Chemistry B

Making and recording of appropriate observations during chemical reactions including changes in temperature and the measurement of rates of reaction by a variety of methods such as production of gas and colour change.

WJEC Eduqas GCSE (9–1) Chemistry

Investigation into the effect of one factor on the rate of reaction using a gas collection method.

Investigation into the effect of one factor on the rate of reaction between dilute hydrochloric acid and sodium thiosulfate.

Investigation into the effect of various catalysts on the decomposition of hydrogen peroxide.

You can reinforce students’ ideas about rates and reactions by including a wide range of relevant practical work, demonstrations and activities into their studies, not just to satisfy the requirements of examination boards. There are many experiments you can use and some of these were discussed in an earlier article (rsc.li/2D8sIqI). Conservation of mass can be investigated in a spectacular precipitation of lead iodide reaction to reinforce the idea that reactions involve the rearrangement of particles (rsc.li/2FG0rtt). A simple experiment using the ethanedioate (oxalate) in rhubarb stems to decolourise acidified permanganate and to investigate the effect of surface area (rsc.li/2EKK3qc) seems more approachable and relevant to students than marble chips dissolving in acid.

Students’ understanding of a topic will improve if the approach is varied and this can be achieved by developing a series of experiments. For instance, there are a number of experiments involving the production of gases. You can use these to help students understand the effect of concentration on the rate of reaction. These experiments also develop their mathematical skills in processing results or developing an investigative approach to a problem. An experiment on the reaction between magnesium and acid uses simple laboratory apparatus (rsc.li/2DzGrId), while an activity on solving an industrial problem can put these ideas into a realistic context (rsc.li/2B7qINW).

Students are fascinated by sudden changes in a reaction. For this reason, variations on the iodine clock reaction can engage students. You can show this as a demonstration (rsc.li/2B4Y67N) or challenge your students to produce a mixture that will suddenly change colour after a defined time (rsc.li/2my8ShE). This practical activity can harness students’ natural competitiveness, engage them in applying their ideas and develop their investigative and laboratory skills.

There are many experiments on the effect of catalysts on the rate of reaction and many suggestions have been made in a previous article (rsc.li/2xcQluG).

You can reinforce students’ ideas about rates and reactions by including a wide range of relevant practical work, demonstrations and activities into their studies, not just to satisfy the requirements of examination boards. There are many experiments you can use and some of these were discussed in an earlier article . Conservation of mass can be investigated in a spectacular precipitation of lead iodide reaction to reinforce the idea that reactions involve the rearrangement of particles. A simple experiment using the ethanedioate (oxalate) in rhubarb stems to decolourise acidified permanganate and to investigate the effect of surface area seems more approachable and relevant to students than marble chips dissolving in acid.

Students’ understanding of a topic will improve if the approach is varied and this can be achieved by developing a series of experiments. For instance, there are a number of experiments involving the production of gases. You can use these to help students understand the effect of concentration on the rate of reaction. These experiments also develop their mathematical skills in processing results or developing an investigative approach to a problem. An experiment on the reaction between magnesium and acid uses simple laboratory apparatus, while an activity on solving an industrial problem can put these ideas into a realistic context.

Students are fascinated by sudden changes in a reaction. For this reason, variations on the iodine clock reaction can engage students. You can show this as a demonstration or challenge your students to produce a mixture that will suddenly change colour after a defined time. This practical activity can harness students’ natural competitiveness, engage them in applying their ideas and develop their investigative and laboratory skills.

There are many experiments on the effect of catalysts on the rate of reaction and many suggestions have been made in a previous article .

Practical problems and suggested solutions

Rate of reaction experiment

Source: © Martyn F Chillmaid/Science Photo Library

The traditional experiment in which sodium thiosulfate solution reacts with acid is potentially hazardous as sulfur dioxide is released as a reaction product. This is particularly risky when investigating the effect of temperature on rate as the sulfur dioxide is driven out of solution at elevated temperatures. This can be especially noxious if the experiment is done as a whole class practical and potentially dangerous for students with asthma. It is important every group is provided with a ‘stop bath’ of sodium hydrogencarbonate solution mixed with an indicator. The reaction mixture should be poured into the stop bath as soon as the mixture shows the desired cloudiness. The acid and the sulfur dioxide are neutralized instantly and the indicator will show when the stop bath is no longer effective. The hazards of sulfur dioxide can also be mitigated by reducing the scale of the experiment – details are available from CLEAPSS (subscription required). 

The traditional experiment in which sodium thiosulfate solution reacts with acid is potentially hazardous as sulfur dioxide is released as a reaction product. This is particularly risky when investigating the effect of temperature on rate as the sulfur dioxide is driven out of solution at elevated temperatures. This can be especially noxious if the experiment is done as a whole class practical and potentially dangerous for students with asthma. It is important every group is provided with a ‘stop bath’ of sodium hydrogencarbonate solution mixed with an indicator. The reaction mixture should be poured into the stop bath as soon as the mixture shows the desired cloudiness. The acid and the sulfur dioxide are neutralized instantly and the indicator will show when the stop bath is no longer effective. The hazards of sulfur dioxide can also be mitigated by  reducing the scale of the experiment (subscription required).

Some schools use expensive glass gas syringes to measure the volume of gas produced. Gas syringes work really well when properly maintained and kept clean and dry. However, too much gas can cause the syringe plunger to fall out break. Tie a piece of string between the barrel and the plunger to limit the travel of the plunger and avoid expensive breakages. You can use plastic syringes for gas measurements but they need to be lubricated with a silicone lubricant for the plunger to move easily. Glass gas syringes must not be lubricated as the plunger will stick.

Mathematical skills

A barrier to students’ understanding of rates is the mathematical skill they need to process numerical observations. Students often categorise their learning into subjects and do not transfer their learning between classes. This can be exacerbated if they are required to use skills in their chemistry lessons before they have been taught them in their mathematics classes. In my experience, a meeting between school departments can resolve this and ensure we ‘speak the same language’ with consistent techniques and notations.

Constant practice analysing numerical observations, processing data and drawing and interpreting graphs will ease students’ difficulties in maths and give them confidence when faced with such exercises in examinations. The table of resources below gives some examples that may help students overcome mathematical barriers to understanding.

Arithmetic and numerical computation

When conducting rates of reaction experiments, students need to process a considerable amount of data. They need to be able to use reciprocals (rate ∝ 1/t), and recognise and use expressions in decimal and standard form – when using reciprocal time as a measure of rate, the resultant numbers will be very small and many students find handling this data quite difficult.

Translate data between graphical and numeric form

When processing their results, students need to present their data in appropriate graphical form and interpret graphs.

Draw and use the slope of a tangent to a curve as a measure of rate of change

Understanding the significance of the gradient of a graph is central to students’ ability to interpret the data in rate experiments.

Useful resources for checking student understanding or explaining rates of reaction

What happens to particles when new materials are made? rsc.li/2B5l7r6

What is a chemical reaction? rsc.li/2DlzOeM

These activities explore students’ understanding of particles in a chemical reaction.

Starter for 10 – Collision theory: rsc.li/2B5BvrB

A set of quick fire questions that explore students’ understanding of experiments relating to collision theory.

Rates of reaction graphs: rsc.li/2DbhD8x

This activity explores students’ ability to interpret graphical representations of the progress of reactions.

Useful resources for checking student understanding or explaining rates of reaction

cal reaction?

These activities explore students’ understanding of particles in a chemical reaction.

A set of quick fire questions that explore students’ understanding of experiments relating to collision theory.

This activity explores students’ ability to interpret graphical representations of the progress of reactions. 

Synoptic approach and Learn Chemistry resources

Early in their study of rates, students will be best served by simple experiments that cover a single aspect of the topic. However, it is important to develop a synoptic approach as their confidence and skills develop. Exam boards expect some work to be done in open-ended investigative projects (see the table ’Practical work required by GCSE specifications’). Many of the Learn Chemistry resources suggested throughout this article offer opportunities for such an approach.

Acknowledgments

Thanks to Dorothy Warren and Kay Stephenson for their help with this article.

David Everett is a retired chemistry teacher with 38 years’ experience in the classroom. He is now an independent science education consultant.

David Everett

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  • Published: 25 June 2024

Responses of growth and photosynthesis to alkaline stress in three willow species

  • Shenqi Qiao 1 ,
  • Changming Ma 1 , 2 ,
  • Hongjiao Li 1 ,
  • Yu Zhang 1 ,
  • Minghui Zhang 1 ,
  • Wenhao Zhao 1 &
  • Bingxiang Liu 1 , 3  

Scientific Reports volume  14 , Article number:  14672 ( 2024 ) Cite this article

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Metrics details

  • Light responses
  • Photosynthesis
  • Plant physiology
  • Plant sciences
  • Plant stress responses

Investigating differences in resistance to alkaline stress among three willow species can provide a theoretical basis for planting willow in saline soils. Therefore we tested three willow species ( Salix matsudana , Salix gordejevii and Salix linearistipularis ), already known for their high stress tolerance, to alkaline stress environment at different pH values under hydroponics. Root and leaf dry weight, root water content, leaf water content, chlorophyll content, photosynthesis and chlorophyll fluorescence of three willow cuttings were monitored six times over 15 days under alkaline stress. With the increase in alkaline stress, the water retention capacity of leaves of the three species of willow cuttings was as follows: S. matsudana  >  S. gordejevii  >  S. linearistipularis and the water retention capacity of the root system was as follows: S. gordejevii  >  S. linearistipularis  >  S. matsudana . The chlorophyll content was significantly reduced, damage symptoms were apparent. The net photosynthetic rate (Pn), rate of transpiration (E), and stomatal conductance (Gs) of the leaves showed a general trend of decreasing, and the intercellular CO 2 concentration (Ci) of S. matsudana and S. gordejevii first declined and then tended to level off, while the intercellular CO 2 concentration of S. linearistipularis first declined and then increased. The quantum yield and energy allocation ratio of the leaf photosystem II (PSII) reaction centre changed significantly (φPo, Ψo and φEo were obviously suppressed and φDo was promoted). The photosystem II (PSII) reaction centre quantum performance index and driving force showed a clear downwards trend. Based on the results it can be concluded that alkaline stress tolerance of three willow was as follows: S. matsudana  >  S. gordejevii  >  S. linearistipularis . However, since the experiment was done on young seedlings, further study at saplings stage is required to revalidate the results.

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A trait-based root acquisition-defence-decomposition framework in angiosperm tree species

Introduction.

Soil salinisation is one of humanity's most severe environmental problems and a pivotal constraint to agroforestry development 1 . Globally, the area of saline soil is approximately 0.64 billion hm 2 and is growing at a rate of 1.5 × 10 6 per year 2 . Saline soils in China are mainly distributed on the eastern coast and in the northwestern arid areas 3 , the land use efficiency is low. Therefore, screening alkaline-tolerant plants by experimentally simulating different saline environments significantly improves saline land use efficiency. Most scholars working on screening and evaluating plant alkaline tolerance have focused on growth and development status, microstructure, photosynthetic pigments, photosystems, ion uptake and transport characteristics, and fluorescence parameters 4 . Current studies on the effects of alkaline stress on plants have focused on cash crops such as Hordeum bogdanii , Oryza sativa L. and Beta vulgaris L. 5 , 6 , 7 , with fewer studies on forest trees.

Willow ( Salix babylonica ) is a woody plant of the Salicaceae family distributed in the north temperate zone 8 . Due to its attractive crown shape and green foliage, willow has excellent characteristics, such as fast sprouting, flood resistance, and salinity tolerance. It is widely used in saline-alkaline land reclamation projects. In addition to neutral salts dominated by NaCl, alkaline salts are dominated by Na 2 CO 3 in the soil 9 . According to Zhao et al. 10 , plants can adapt to alkaline environments by thickening their epidermis and flesh, shrinking their leaves, and altering their tissue structure. The high pH of alkaline stress disrupts plant ion homeostasis, hinders photosynthesis and photosynthetic pigment production, damages biomolecules such as DNA, lipids and proteins, and causes slow growth and even death of plants 11 . Currently, studies on the physiological aspects of stress tolerance mainly focus on the physiological characteristics of pests and diseases, heavy metals, salinity, and water 12 . Little has been reported on the changes in the water content of root and leaf tissues and the photosynthetic system under alkaline stress, while there are few reports on the relationship between the water uptake and utilisation efficiencies of roots and leaves and the photosynthetic system under alkaline stress. This experiment aimed to clarify the changes in the plant tissue water content and photosynthetic system of S. matsudana , S. gordejevii and S. linearistipularis under alkaline stress to clarify the salt tolerance mechanism of the three willow species in regards to tissue water content and photosynthetic system. Comparative analysis of the alkaline stress resistance of the three willow cuttings will provide a theoretical reference for the selection and cultivation of saline and alkaline tree species.

Materials and methods

Experimental materials and design.

The experimental site was located at the West Campus of Hebei Agricultural University, Baoding City, Hebei Province. The temperature of the climate chamber was set at 28 °C/25 °C (light/dark), light intensity was controlled by an LED cold light source at 1000 μmol m −2  s −1 , photoperiod was 14 h/10 h (light/dark), relative humidity was 60%.

The test materials were collected from the germplasm resource nursery of Jinsha Beach Forestry Farm, Huai'an County, Hebei Province. The branches of three willow species, S. matsudana , S. gordejevii and S. linearistipularis , which were the same in length and strong without pests and diseases, were collected in the early spring before bud break and then stored in a freezer at 0 °C. The hydroponic test was started in the artificial climate chamber of Hebei Agricultural University, Baoding City, Hebei Province. Before the experiment, The middle two-thirds of the selected branches were.

cut into 20 cm-long cuttings. The uppermost bud was 0.5–1 cm from the top of the cuttings. Adequate number of willow cuttings were grown in fresh water and managed regularly. When their growth reached the treatment requirements (average root length of approximately 5 cm), cuttings with uniform growth and root systems were selected to start the alkaline stress treatment experiment.

The cuttings were placed in 55 cm × 38 cm × 15 cm (L × W × H) plastic boxes for hydroponics with five treatments. Hydroponic solutions with pH values of 8.0, 8.5, 9.0, and 9.5 (mNa 2 CO 3 : mNaHCO 3  = 1:1) were prepared using 1/2 Hoagland complete nutrient solution as the background solution and 1/2 Hoagland complete nutrient solution as a control (CK). The pH of CK was 7.2. Each treatment was replicated three times, and 20 cuttings were placed in each replication and directly immersed in the solution, approximately half the cuttings' height (Fig.  1 ). The nutrient solution was changed every 5 days during the growth process. Before the nutrient solution was changed, the cuttings were removed and the roots were rinsed with water to wash away the last residual salt and prevent excessive salt accumulation. We randomly selected three seedlings with even growth vigor on the 1st, 3rd, 5th, 8th, 11th, and 15th days of the stress test for the observation of various growth physiological indexes. The measurement of each index was repeated for 3 times, and the growth status was observed and recorded 1 week after the end of the experiment.

figure 1

Design of three willows experimental treatment.

Measurements of various indicators

The water content of roots and leaves, the chlorophyll content of leaves were measured using the method of Li 13 . The plant samples were all cut off and put in the weighing bottle respectively, then put into the oven to kill at 105 °C for 15 min and then dried at 80–90 °C to constant weight after end of killing. Set the weight of the weighing bottle as W 1 , the weight of the weighing bottle and the plant sample as W 2 , and the weight of the weighing bottle and the dried plant sample as W 3 , water content (%) of the plant tissues can be calculated according to the following formula: total water content of the plant tissues = (W 2 −W 3 )/(W 2 −W 1 ) × 100%.

Weigh 0.2 g of leaf blade and soaked in 95% ethanol for 24 h. The chlorophyll extract was poured into a 1 cm aperture cuvette. The absorbance was measured at 665 nm and 649 nm using 95% ethanol as blank. The concentrations of chlorophyll a ( 1 ), chlorophyll b ( 2 ) and total chlorophyll ( 3 ) were then calculated using the following equations.

The chlorophyll fluorescence parameters were measured using the method developed by Ran et al. 14 . The leaves were dark-adapted for 15 min before measurement, and their fast chlorophyll fluorescence induction kinetic curves and related parameters were determined using a Pocket PEA Plant Efficiency Analyser (Hansatech, UK). We performed the following analyses and calculations: initial fluorescence (Fo), maximum fluorescence (Fm) and maximum photochemical efficiency (Fv/Fm) of the leaves after dark adaptation and the performance index (PI ABS ) based on absorbed light energy.

Photosynthetic parameters were measured using Ran Xin's method 14 . During the stress treatments, three cuttings with uniform growth were selected each time for each treatment. Using a Li-6800 portable photosynthesiser (LI-COR, USA), we measured the stomatal conductance (Gs), intercellular CO 2 concentration (Ci), transpiration rate (E), and net photosynthetic rate (Pn) in a climatic chamber. We ensured that the leaves had the same size direction of exposure to light and were fully expanded and functional. The measurement conditions were as follows: PAR of 1000 μmol m −2  s −1 , CO 2 concentration of 400 μmol mol −1 in the fixed system, and relative humidity of 60%.

Data analysis

Plotting was performed using Origin 2021 software, experimental data for root and leaf moisture content of three willow cuttings was analysed using SPSS 18.0 data processing software for statistical analysis. One-way ANOVA and least significant difference (LSD) method was used to check the significance of the difference when the P -value was less than 0.05 and 0.01, respectively.

Germplasm collection license statement

Permission to collect three willow cuttings was obtained prior to the collection of experimental material and is hereby declared.

Experimental guidelines and license disclaimer

All procedures of the experiment were carried out in accordance with the guidelines, and the whole process of the experiment was approved. The experiment was carried out in accordance with national and regional regulations.

Changes in the growth status, root and leaf dry weights of three willow cuttings under alkaline stress

Changes in the external morphology of plants can intuitively reflect the strength of their alkaline tolerance. The changes in the growth of the three willow cuttings at different pH values were shown in Fig.  2 a, b and c, which showed that the growth damage increased with the increase of pH. The number of damaged leaves gradually increased as the leaf tips, margins or veins of the leaves turned yellow until they wilted and fell off, and the branches dried up with a decrease in the root system, which was severe damage. Comparatively, S. matsudana maintained better external morphology at higher pH, followed by S. gordejevii , while S. linearistipularis suffered most severely under alkaline stress.

figure 2

Effects of alkaline stress on the morphology of three willow cuttings ( a : S. matsudana ; b : S. gordejevii ; c : S. linearistipularis ). Note: From left to right are the changes of willow cuttings growth with the increase of pH on the 8th day of stress.

The root and leaf dry weights of the three willow cuttings exhibited distinct variations under alkaline stress at different pH levels (Table 1 ). Specifically, the leaf dry weights of Salix matsudana showed significant differences at pH 9.0 compared to the control. Moreover, the leaf dry weight of Salix gordejevii and Salix linearistipularis significantly differed at pH 8.0 compared to the control. For Salix matsudana , the root dry weight only exhibited significant differences from the control at pH 9.0. Conversely, the root dry weights of Salix gordejevii and Salix linearistipularis significantly differed from the control at pH 8.0 and pH 8.5, respectively. Additionally, across all pH levels, Salix matsudana consistently displayed higher root and leaf dry weights, while Salix linearistipularis exhibited lower root and leaf dry weights. Salix gordejevii showed intermediate values for both root and leaf dry weights, positioning it between the other two willow species.

Effects of alkaline stress on the water content of three willow cuttings

As in from Fig.  3 , the root and leaf water content of the three willow cuttings was affected to different degrees under different concentrations of alkaline stress, and root and leaf water content showed an overall decreasing trend with increasing pH. When the pH of the alkaline solution was 8.0 and 8.5, the leaf water content of the three willow cuttings decreased, but there was no significant difference compared with that of the control group (Fig.  3 a, b, c). When the pH of the alkaline solution was 9.0 and 9.5, the leaf water content of the three willow cuttings decreased significantly, with the most significant decrease occurring in S. linearistipularis (Fig.  3 c). This result indicated that the water retention capacity of S. linearistipularis leaves was the worst among the three willow cuttings under high concentrations of alkaline stress.

figure 3

Effects of alkaline stress on the leaf water content ( a : S. matsudana ; b : S. gordejevii ; c : S. linearistipularis ) and root water content ( d : S. matsudana ; e : S. gordejevii ; f : S. linearistipularis ) of three willow cuttings.

At alkaline stress pH values of 8.0 and 8.5, there was no significant difference in the root water content of S. matsudana and S. gordejevii compared with the control (Fig.  3 d, e). When the pH was 9.0 and 9.5, the root water content of S. matsudana and S. gordejevii decreased significantly compared with that of the control. In contrast, the difference in root water content of S. linearistipularis was only significant at pH 9.5 compared with the control (Fig.  3 f). The water retention capacity of three willow cuttings' roots were in the order of S. linearistipularis  >  S. gordejevii  >  S. matsudana .

Effects of alkaline stress on the chlorophyll content of three willow cuttings

As seen in Table 2 , the changes in chlorophyll a, chlorophyll b and total chlorophyll content of the leaves of the three willow cuttings were consistent with a decreasing trend. S. linearistipularis showed the most significant decrease under alkaline stress at different pH values, while S. matsudana showed the smallest. At pH 8.0, the total chlorophyll contents of the three willow cuttings decreased by 1.40%, 10.30% and 17.70%, respectively, compared with the control.

Effects of alkaline stress on photosynthetic gas exchange parameters in three willow cuttings

Photosynthesis is an essential pathway for biosynthesis and physiological metabolism during the growth and development of plant bodies and is more sensitive to changes in the external environment. Photosynthesis is an important indicator of the level of alkalinity resistance in plants. Figure  4 shows that S. linearistipularis had the lowest level of photosynthetic gas exchange among the three willow cuttings. The alkaline stress treatment concentration increased, and the leaf Pn, Gs and E of the three willow cuttings decreased significantly. Intercellular CO 2 concentration of S. matsudanau leaves and S. gordejevii leaves showed a decreasing trend under alkali stress, and that of S. linearistipularis leaves showed a decreasing and then increasing trend (Fig.  4 j, k, l).

figure 4

Effects of alkaline stress on net photosynthetic rate ( a : S. matsudana ; b : S. gordejevii ; c : S. linearistipularis ), stomatal conductance ( d : S. matsudana ; e : S. gordejevii ; f : S. linearistipularis ), transpiration rate ( g : S. matsudana ; h : S. gordejevii ; i : S. linearistipularis ), and intercellular CO 2 concentration ( j : S. matsudana ; k : S. gordejevii ; l : S. linearistipularis ) of three willow cuttings.

Changes in the rate of decline of Pn in the leaves of the three willow cuttings differed with increasing pH. The rate of Pn decline in S. gordejevii and S. linearistipularis peaked between pH CK-8.0. They slowed down significantly between pH 8.0–9.5, whereas the rate of Pn decline in S. matsudana leaves was more stable throughout alkaline stress (Fig.  4 a, b, c).

Effects of alkaline stress on chlorophyll fluorescence kinetic parameters in three willow cuttings

Effects of alkaline stress quantum yield and energy partition ratio of three willow cuttings.

As shown in Fig.  5 , the trends of the quantum yield and energy allocation ratios of the leaves of the three willow cuttings under alkaline stress were generally consistent, all of which showed an overall gradual decrease in φPo, Ψo, and φEo and an overall gradual increase in φDo with the aggravation of the stress. There were differences in tolerance to alkaline stress among different species. S. matsudana showed better index stability under alkaline stress than the other two willows (Fig.  5 a, d, g, j). Notably, S. gordejevii was able to better regulate its adaptive capacity to the adverse environment by changing the energy absorbed, converted, used for electron transfer and dissipated by heat radiation in the leaves at lower pH (pH < 9) under alkaline stress, during which its indices were less inhibited than those of the other two willows. From the point of view of energy utilisation, S. gordejevii had a more vital short-term alkaline stress tolerance ability. However, with further aggravation of the alkaline stress, the indices changed abruptly. The speed and magnitude of the changes were greater than those of S. matsudana and S. linearistipularis , and the degree of damage was significant (Fig.  5 b, e, h, k).

figure 5

Effects of alkaline stress on the quantum ratio of heat dissipation φDo ( a : S. matsudana ; b : S. gordejevii ; c : S. linearistipularis ), the quantum efficiency of electron transfer from electron acceptors φEo ( d : S. matsudana ; e : S. gordejevii ; f : S. linearistipularis ), the maximal photochemical efficiency of PS II φPo ( g : S. matsudana ; h : S. gordejevii ; i : S. linearistipularis ), and the ratio of transferred electrons to trapped electrons φDo ( j : S. matsudana ; k : S. gordejevii ; l : S. linearistipularis ) of three willow cuttings.

Effects of alkaline stress on leaf performance indices and propulsion of three willow cuttings

As shown in Table 3 , the changes in the PI ABS and PI CSm of S. matsudana leaves were the same, and both showed an overall decreasing trend with increasing pH. The DF CSm of S. matsudana leaves showed an overall decreasing trend with increasing pH, and the differences were significant when the pH was 8.5, 9.0 and 9.5 compared with the control group. S. gordejevii leaf PI ABS , PI CSm and DF CSm all showed a trend of increasing and then decreasing with increasing pH. The three indices peaked when the pH was 8.0 and then decreased significantly with increasing pH in all treatments compared with the control group. The PI ABS, PI CSm and DF CSm of S. linearistipularis leaves showed an overall decreasing trend with increasing pH, and each treatment group decreased significantly compared with the control group.

Correlation analysis of indicators of three willow cuttings under alkaline stress

The relationship between 16 indicators of S. matsudana root and leaf water content, chlorophyll content, and photosynthesis can be determined by analysing a heatmap of the correlation matrix. From Fig.  6 a, it is evident that in S. matsudana, there are 92 pairs of indicators with a highly significant correlation level \((P \leqq 0.01)\) , 5 pairs with a significant correlation level \((P \leqq 0.05)\) , and 22 pairs with no correlation or insignificant correlation. The correlation between root water content and other indicators was insignificant except for the highly significant correlation between root and leaf water content. The intercellular CO 2 concentration in S. matsudana leaves had weak or no correlation with other indicators except for a highly significant correlation with stomatal conductance and significant correlations with chlorophyll b, net photosynthetic rate, transpiration rate, PI ABS and PI CSm .

figure 6

Correlation analysis of indicators of three willow cuttings under alkaline stress ( a ) S. matsudana ; ( b ) S. gordejevii ; ( c ) S. linearistipularis.

There were 105 pairs of highly significant correlations \((P \leqq 0.01)\) , 4 pairs of significant correlations \((P \leqq 0.05)\) , and 10 pairs of weak or nonexistent correlations among the indicators in S. gordejevii (Fig.  6 ). The intercellular CO 2 concentration of S. gordejevii showed weak or no correlation with most indicators, except for a negative correlation with root and leaf water content and significant correlations with φPo, φDo, and DF CSm . The correlation between Pn and leaf water content did not reach the level of significance, which was different from that of S. matsudana and S. linearistipularis .

In S. linearistipularis , 109 pairs of indicators had highly significant correlations \((P \leqq 0.01)\) , two pairs of indicators had significant correlations \((P \leqq 0.05)\) , and the correlations between the other indicators were weak or nonexistent (Fig.  6 c). The cellular CO 2 concentration of S. linearistipularis leaves showed a highly significant negative correlation with root and leaf water content, Ψo, φEo and DF CSm , a significant negative correlation with φPo, a significant positive correlation with φDo, and a weak or nonexistent correlation with the other indicators. Except for the intercellular CO 2 concentration, there were highly significant correlations between the other indicators.

Analysis of changes in root and leaf dry weight of three willow cuttings under alkaline stress

Often forest trees trade reduced growth for survival in alkaline environments. The change in biomass is an integrated expression of the plant's response to stress and is one of the direct indicators representing the plant's alkaline tolerance. As one of the main organs for material exchange in plants, the growth of the root system is closely related to the growth and development of the above-ground parts, whether the root system can function properly, and the efficiency of water and nutrient utilisation by plants 15 , 16 . However, because of its direct contact with adversity stress, it can be the earliest to feel the signals of adversity stress and become the first and foremost site of damage 17 . It has been shown that the metabolic regulation of roots is the first barrier for plants to cope with saline and alkaline stress 18 , 19 , and in particular, the alkaline resistance of plants mainly depends on roots 20 . This study found that the dry weights of roots and leaves of three willow cuttings generally tended to decrease during alkaline stress. The dry weight of the root system of S. matsudana , which is highly alkaline tolerant was always maintained at a high level. S. gordejevii root dry weight also maintained a stable state at higher levels, although it changed significantly under low pH stress. S. linearistipularis root system dry weight remained low and decreased significantly at pH 8.5. Therefore, the alkaline tolerance of the three willow cuttings was thus S. matsudana  >  S. gordejevii  >  S. linearistipularis .

Analysis of changes in root and leaf water content of three willow cuttings under alkaline stress

Salinity stress can lead to osmotic pressure imbalance in the plant, preventing water uptake and, in severe cases, leading to water exudation or even plant death 21 . In this experiment, the water content of the root systems of S. gordejevii and S. linearistipularis decreased by approximately the same amount. In contrast, the water content of the root system of S. matsudana decreased by the most significant amount. However, the water content of S. matsudana leaves was able to remain stable. S. matsudana reduced root water uptake as much as possible without affecting the growth of the root system, which is an essential mechanism for plant adaptation to saline and alkaline stress. This supports Jia's study on the impact of alkaline stress on hickory's photosynthetic properties 22 . Yang et al. pointed out in their study on alfalfa that plant water loss can be used as a rapid and economical osmotic adjustment to cope with osmotic imbalance brought about by saline and alkaline stress 23 . The results of this study showed that the stability of the leaf water content of the three willow cuttings was a vital reflection of the strength of their resistance. S. matsudana leaf water content remained stable throughout the alkaline stress period, S. gordejevii leaves retained water better under low-concentration stress, and S. linearistipularis leaves retained water the least. This difference in water uptake among willow species may be due to variations in their ability to accumulate osmoregulatory substances, which affect osmotic pressure.

Analysis of changes in photosynthetic pigments and the photosynthetic system of three willow cuttings under alkaline stress

Photosynthesis in plant leaves depends mainly on the absorption, transfer and conversion of light energy in Thylakoid Membrane 24 . Studies have shown that photosystem II (PSII) is the most sensitive to salinity stress, and chloroplasts are one of the most essential organelles in plant PS II that respond to salinity stress 25 . Chlorophyll a and chlorophyll b are concentrating pigments that are not photochemically active. They are mainly responsible for absorbing light energy and transferring it to the unique chlorophyll pair in the reflection centre during photosynthesis 26 . Changes in the external environment will directly affect the chlorophyll content of leaves, which in turn will impact the photosynthetic function of plants. Therefore, chlorophyll content has become an important reference index for plant salinity tolerance 27 . In addition, Mg 2+ and Fe 2+ , as essential elements for chlorophyll synthesis and chloroplast structure, precipitate at high pH, which is one of the reasons for the decrease in plant chlorophyll content due to alkaline stress 28 . In this study, we found that during alkaline stress, the photosynthetic pigment content of the three willow species varied in a gradual decline with increasing pH during alkaline stress. S. matsudana was able to ensure the relative stability of its photosynthetic pigment content during alkaline stress and was less affected by alkaline stress, followed by S. gordejevii . Furthermore, S. linearistipularis showed the most significant decrease in photosynthetic pigment content. The total chlorophyll content of the three willow cuttings showed significant differences in their sensitivity to low concentrations of alkaline stress, with S. linearistipularis  >  S. gordejevii  >  S. matsudana . This indicates that alkaline stress destroys the plant environment, affects the physiological functions of the plant, reduces the stability of the cyst-like membrane, significantly inhibits the synthesis of chlorophyll, and accelerates the decomposition of chlorophyll by increasing chlorophyll hydrolase, thus weakening the absorption of light energy by chlorophyll 29 . However, there were significant differences in the magnitude and rate of decline in chlorophyll content of the three willow cuttings under alkaline stress, which may be related to the resistance of the tree species to saline and alkaline stress.

Photosynthesis, as a critical anabolic process of plant material energy sources, not only provides energy for the average growth, development and physiological metabolism of plants but is also more sensitive to adverse environments and is one of the critical indicators for determining the damage status of plants 30 . Alkaline stress is one of the critical factors for the inhibition of plant photosynthesis compared to salt stress. In addition to ionic toxicity and osmotic stress from high concentrations of salt ions in the plant body, high pH stress in the interroot is also one of the critical factors for inhibiting plant photosynthesis 31 . Studies have demonstrated that plants can recover from the effects of salt stress. The degree of recovery from damage to the acceptor side of the PS II reaction centre under salt stress was close to 100%. The degree of recovery from damage to the donor side was less than 85%.

In contrast, the effects of alkaline stress on the photosynthetic system of phytomass were not reversible, which may be related to the effect of high pH of alkaline stress on the plant 32 . In addition, alkaline stress inhibits chlorogenesis and reduces the photosynthetic area and carbon assimilation in monocots, which results in physiological metabolic disorders and the accumulation of toxic substances 33 . Salinity stress inhibits energy-related processes, such as photosynthesis, carbohydrate metabolism, and the TCA cycle 34 .

The net photosynthetic rate, as a critical indicator of photosynthesis, can straightforwardly reflect the material production capacity of plants per unit leaf area 35 . Based on previous studies, limiting factors affecting photosynthesis under adverse stress can be categorised into two main groups: stomatal limitation and nonstomatal limitation 36 . In this study, the leaf Pn, Gs and E of all three willow cuttings decreased significantly with increasing pH. Among them, S. matsudana was better able to maintain the stability of its own Pn under more substantial stress concentrations. Furthermore, S. gordejevii and S. linearistipularis were significantly inhibited at the beginning of alkaline stress. The reduction in transpiration rate and stomatal conductance may be an adaptive response to the reduction in water content, which is consistent with the reduction in willow leaf water content in the results of this experiment 37 . Reducing the transpiration rate as much as possible without affecting the photosynthetic rate is essential for plant adaptation to adversity 38 . Leaf Ci decreased with decreasing Gs at lower pH in three willow cuttings, showing typical stomatal factor limitation 39 . At higher pH for the three willow cuttings, S. matsudana and S. gordejevii leaf Ci did not change significantly with decreasing Gs. S. linearistipularis leaf Ci increased with decreasing Gs, showing typical nonstomatal factor limitation. The changes in Ci of S. matsudana and S. gordejevii leaves indicated that the two types of willows were less affected by nonstomatal limiting factors under high alkaline stress, which differed from the results of previous studies and might be highly related to the unique salinity resistance mechanism of the two types of willows.

Analysis of changes in chlorophyll fluorescence kinetic parameters in three willow cuttings under alkaline stress

φPo, Ψo, φEo and φDo reflect the energy allocation ratio of plants. In this study, at lower pH at the beginning of alkaline stress, all fluorescence indices of the three willow cuttings showed no significant difference compared with the control group, indicating that the low concentration of alkaline stress had less effect on the energy allocation in the PS II reaction centre of the three willow cuttings, which was the same as the results of Zhang et al. 40 . With stress intensification, φPo, Ψo, and φEo significantly decreased while φDo significantly increased in S. gordejevii and S. linearistipularis , and the magnitude of changes was positively correlated with stress intensity. S. matsudana φPo, Ψo, φEo and φDo had the same trend of change as those of the other two willows, but the magnitude of change was smaller, and φPo differed from the control only at pH 9.5. The three willow cuttings adjusted the energy allocation ratios of their own PS II reaction centres under alkaline stress, i.e., the quantum ratio of energy absorbed by antenna pigment cells for heat dissipation increased and the energy share of photochemical reactions decreased 41 . Plants rely on light energy through photosynthesis to synthesise organic matter. However, too much light energy can harm their photosynthetic apparatus. To prevent damage, excess energy is dissipated through the lutein cycle for photoprotection, according to Barbara et al. 42 . To reduce the damage to the photosynthetic apparatus caused by excess light energy, plants will also appropriately reduce chlorophyll content to reduce the capture of excess light energy without affecting photosynthesis, which is also a self-regulatory mechanism for plants to cope with stress 43 , 44 . In conclusion, the three willow cuttings showed different degrees of decreases in φPo, Ψo and φEo, indicating that the photosynthetic apparatus was significantly damaged and that the ability of the PSII receptor side Q A to transfer electrons and the ability of Q B and PQ to be reduced were reduced, as evidenced by the reduced opening of the active reaction centres and the inhibition of the electron transfer process 45 . Compared with the three willow cuttings, S. matsudana had the most vital ability to maintain its stability under alkaline stress; S. gordejevii was more tolerant at lower alkaline stress concentrations, but the degree of damage increased rapidly with a further increase in alkaline stress; and S. linearistipularis was the least resistant throughout the alkaline stress process.

Plants are prone to photoinhibition or exacerbation in adverse environments, and PI ABS can comprehensively reflect the activity of photosystems through the three aspects of absorption, capture and electron transfer of light energy under adverse conditions 46 . In this study, the overall trend of decreasing PI ABS , PI CSm and DF CSm in the leaves of the three willow cuttings showed a more obvious decreasing trend with the increasing degree of alkaline stress, among which S. matsudana showed a minor change, S. gordejevii showed a more vital ability to tolerate the low concentration of stress, and S. linearistipularis showed the most apparent decreasing trend. This indicates that alkaline stress seriously affects the absorption and utilisation of light energy and leads to a decrease in the basal driving force, and the degree of reduction in PSII activity varies among different species of willow leaves. The stress triggered photoinhibition, reversible inactivation or irreversible degradation of the PSII reaction centre, reduced light energy conversion efficiency and impaired functioning of the photosynthetic apparatus in willow leaves, thus limiting the normal conduct of photosynthesis.

Analysis of correlation differences among indicators of three willow cuttings under alkaline stress

Correlation analysis among indicators of three willow cuttings under alkaline stress. This study showed no significant correlation between the root water content of S. matsudana and other indicators, except for a significant positive correlation with leaf water content \((P \leqq 0.05)\) . Unlike S. matsudana, the correlation between root system water content and other indicators of S. gordejevii and S. linearistipularis reached a significant level \((P \leqq 0.01)\) . The difference in correlations among the three willow cuttings may be related to the existence of unique salinity resistance mechanisms in S. matsudana . Compared with S. gordejevii and S. linearistipularis , S. matsudana has better drought resistance, which reduces the effect of alkaline stress on the plant by reducing the water content of the root system and synthesising more osmoregulatory substances to maintain the water content of the leaves without affecting the normal physiological metabolism of the plant. Some studies have shown that the decrease in the water content of alfalfa cuttings under alkaline stress is not only a result of osmotic stress but also may be due to the damage of high pH to the root system structure of the plant body and osmotic regulatory substances 23 . Suitable water content may enable salt-resistant plants to develop less energy-consuming osmotic pressure, thus increasing the resistance of saline plants to stress 47 .

It was also observed in this study that the intercellular CO 2 concentration in S. matsudana was significantly and positively correlated with the net photosynthetic rate \((P \leqq 0.05)\) , transpiration rate \((P \leqq 0.05)\) , and stomatal conductance \((P \leqq 0.01)\) and was not correlated with root and leaf water contents. In contrast, the intercellular CO 2 concentrations in S. gordejevii and S. linearistipularis were not correlated with the net photosynthetic rate, transpiration rate, and stomatal conductance, root and leaf water content was significantly negatively correlated \((P \leqq 0.01)\) . The results indicated that stomatal factors were the main limiting factors for the growth of S. matsudana under alkaline stress. In contrast, nonstomatal factors were the main limiting factors for the growth of S. gordejevii and S. linearistipularis under alkaline stress.

Alkaline stress affected root and leaf dry weight, root and leaf water content, chlorophyll content, photosynthesis and chlorophyll fluorescence kinetic parameters in all three willow cuttings. To some extent, the three willow cuttings can cope with the damage caused by alkaline stress by appropriately reducing the root water content while increasing the water-holding capacity of the leaves. Stronger alkaline stress also inhibited chlorophyll synthesis and accelerated chlorophyll decomposition. At low concentrations of alkaline stress, stomatal closure was the leading cause of decline in all three willow cuttings. In contrast, at high concentrations of alkaline stress, nonstomatal factors were the main factors limiting photosynthesis in all three willow cuttings. S. matsudana and S. linearistipularis photosynthesis were less affected by nonstomatal limiting factors, while S. linearistipularis photosynthesis was significantly nonstomatal limited. In terms of chlorophyll fluorescence kinetic parameters, alkaline stress degraded or inactivated the leaf PSII reaction centre and caused damage to both the donor and acceptor sides of PSII, triggering a series of responses, such as photoinhibition, reduction in light energy conversion efficiency and impaired functioning of the photosynthetic apparatus in the leaves of the three willow cuttings. The correlation between the root water content of S. matsudana and the indicators once again illustrated the idea that plants can cope with alkaline stress by reducing the root water content. Furthermore, a comparison of the correlations between Ci and Pn, Gs and E showed that nonstomatal limiting factors had less inhibitory effects on the growth of S. matsudana and that the growth of S. gordejevii and S. linearistipularis was significantly nonstomatal-limited.

The adaptive mechanisms of the three willow cuttings to alkaline stress differed. The performance of the three willow cuttings showed that S. matsudana could better maintain the relative stability of the indicators at higher alkaline stress concentrations, followed by S. gordejevii, which showed a stronger ability to tolerate low alkaline stress concentrations. However, the rate of change in the indicators increased rapidly with further stress intensification. S. linearistipularis was the least adaptive to the regulation of alkaline stress.

Data availability

Data will be made available on request. You can send us an email to get the raw data. E-mail address: [email protected].

Zhang, X. Y., Bian, J., Zhao, Y., Wang, X. N. & Sun, Y. F. Effects of soda saline-alkali stress on the growth and development of hemp. Chin. Agric. Sci. Bull. 13 , 1–7 (2023).

Google Scholar  

Zhang, J. F., Zhang, X. D., Zhou, J. X. & Li, D. X. World resources of saline soil and main amelioration measures. Res. Soil Water Conserv. 6 , 32–34 (2005).

CAS   Google Scholar  

Ren, X. L., Zhang, W., Liu, X., Luo, Y. Z. & Wei, K. The research development and thinking about the expansibility property of saline soil in northwest region. Chin. J. Soil Sci. 47 , 246–252 (2016).

Dehghan-Harati, Z., Mahdavi, B. & Hashemi, S. E. Ion contents, physiological characteristics and growth of Carum copticum as influenced by salinity and alkalinity stresses. Biologia Futura. 73 , 301–308 (2022).

Article   CAS   PubMed   Google Scholar  

Han, D. et al. Effects of endophytic fungi on the secondary metabolites of hordeum bogdanii under alkaline stress. AMB Express 12 , 1–9 (2022).

Article   Google Scholar  

He, R. et al. ThPP1 gene, encodes an inorganic pyrophosphatase in Thellungiella halophila, enhanced the tolerance of the transgenic rice to alkali stress. Plant Cell Rep. 36 , 1929–1942 (2017).

Zou, C. L. et al. Effects of alkali stress on dry matter accumulation, root morphology, ion balance, free polyamines, and organic acids of sugar beet. Acta Physiologiae Plantarum. 43 , 1. https://doi.org/10.1007/s11738-020-03194-x (2021).

Article   CAS   Google Scholar  

Gao, S. & Song, H. F. Sex-related response of Salicaceae to drought stress. Chin. J. App. Environ. Biol. 27 , 495–502 (2021).

Xu, Y. Q. & Liu, Z. F. Effects of NaCl and nacostresses on photosynthesis and parameters of chlorophyll fluorescence in seedlings. Chin. J. Plant Ecol. 32 , 161–167 (2008).

Zhao, H. X. et al. Response analysis of microstructure of different rice varieties under alkali stress. J. Northeast. Agric. Univ. 11 , 11–22 (2020).

Yan, G., Shi, Y. J., Chen, F. F., Mu, C. S. & Wang, J. F. Physiological and metabolic responses of Leymus chinensis seedlings to alkali stress. Plants 11 , 1494. https://doi.org/10.3390/plants11111494 (2022).

Article   CAS   PubMed   PubMed Central   Google Scholar  

Ran, X. et al. Study on the relationship of Ions (Na, K, Ca) absorption and distribution to photosynthetic response of Salix matsudana koidz under salt stress. Front. Plant Sci. https://doi.org/10.3389/fpls.2022.860111 (2022).

Article   PubMed   PubMed Central   Google Scholar  

Li, H. S. Principles and Techniques of Plant Physiological Biochemical Experimental Vol. 105–134 (Higher Education Press, 2000).

Ran, X., Wang, X., Gao, X. K. & Huang, X. X. Effects of salt stress on the photosynthetic physiology and mineral ion absorption and distribution in white willow ( Salix alba L.). PLoS ONE 16 , e0260086. https://doi.org/10.1371/journal.pone.0260086 (2021).

Yang, Z. Q., Qiu, Y. X. & Liu, Z. X. The effects of soil moisture stress on the growth of root and above-ground parts of greenhouse tomato crops. Acta Ecol. Sin. 36 , 748–757 (2016).

Ding, H., Zhang, Z. M. & Dai, L. X. Effects of water stress and nitrogen fertilization on peanut root morphological development and leaf physiological activities. Chin. J. Appl. Ecol. 26 , 450–456 (2015).

Wang, S. F., Hu, Y. X., Sun, H. Q., Shi, X. & Pan, H. W. Effects of salt stress on growth and root development of two oak seedings. Acta Ecol. Sin. 34 , 1021–1029 (2014).

Wang, H., Lin, X. & Cao, S. Alkali tolerance in rice ( Oryza sativa L.): Growth, photosynthesis, nitrogen metabolism and ion homeostasis. Photosynthetica. 53 , 55–65 (2015).

Gong, B., Wen, D. & Bloszies, S. Comparative effects of NaCl and NaHCO 3 stresses on respiratory metabolism, antioxidant system, nutritional status, and organic acid metabolism in tomato roots. Acta Physiol. Plantarum. 36 , 2167–2181 (2014).

Yang, C. W. Mechanisms of Alkali Tolerance in Chloris virgata and Rice (Ory zasativa) (Northeast Normal University, 2010).

Serraj, R. & Drevon, J. J. Effects of salinity and nitrogen source on growth and nitrogen fixation in alfalfa. J. Plant Nutr. 21 , 1805–1818 (1998).

Liu, J., Liu, Y. Q., Jing, L. L., Sun, S. X. & Wang, Y. Q. Effects of alkali stress on Prunus davidiana (Carr.) leaf morphological structure and photosynthetic characteristics. Southwest China J. Agric. Sci. 30 , 327–332 (2017).

Yang, J. Y., Zheng, W., Tian, Y., Wu, Y. & Zhou, D. W. Effects of various mixed salt-alkaline stresses on growth, photosynthesis, and photosynthetic pigment concentrations of Medicago ruthenica seedlings. Photosynthetica. 49 , 275–284 (2011).

Krause, G. H. & Weis, T. E. Chlorophyll fluorescence and photosynthesis: The basics. Annu. Rev. Plant Physiol. 42 , 313–349 (1991).

Baker, N. R. A possible role for photosystem II in environmental perturbations of photosynthesis. Physiol. Plantarum. 81 , 563–570 (1991).

Wu, C. L. et al. Effects of alkaline stress on growth, photosynthesis and antioxidation of helianthus tuberosus seedlings. Acta Bot. Boreali-Occidentalia Sin. 3 , 447–454 (2006).

Bai, J. H., Jin, K., Qin, W., Wang, Y. Q. & Yin, Q. Proteomic responses to alkali stress in oats and the alleviatory effects of exogenous spermine application. Front. Plant Sci. 12 , 516–524 (2021).

Li, R. L., Shi, F. C. & Yang, Y. L. Effects of salt and alkali stresses on germination, growth, photosynthesis and ion accumulation in alfalfa ( Medicago sativa L.). Soil Sci. Plant Nutr. 56 , 881–892 (2011).

Shi, C. C., Yang, F., Liu, Z. H. & Lin, J. X. Uniform water potential induced by salt, alkali, and drought stresses has different impacts on the seedling of Hordeum jubatum : From growth, photosynthesis, and chlorophyll fluorescence. Front. Plant Sci. https://doi.org/10.3389/fpls.2021.733236 (2021).

Tang, R. et al. Photosynthetic physiological response mechanism of Cyperus esculentus L. seedlings under saline alkali stress. Chin. J. Oil Crop Sci. 44 , 632–641 (2022).

Liu, J. X., Wang, J. C., Wang, R. J. & Jia, H. Y. Effects of salt and alkali stresses on photosynthesis in Avena nuda seedlings. Agric. Res. Arid Areas 33 , 6–18 (2015).

Mehta, P., Jajoo, A., Mathur, S. & Bharti, S. Chlorophyll a fluorescence study revealing effects of high salt stress on photosystem II in wheat leaves. Plant Physiol. Biochem. 48 , 16–20 (2010).

Wang, Q. Z., Liu, Q., Gao, Y. N. & Liu, X. Review on the mechanisms of the response to salinity-alkalinity stress in plants. Acta Ecol. Sin. 16 , 5565–5577 (2017).

Cheng, T. L., Chen, J. H. & Zhang, J. B. Physiological and proteomic analyses of leaves from the halophyte Tangut Nitraria reveals diverse response pathways critical for high salinity tolerance. Front. Plant Sci. 6 , 30–42 (2015).

Li, X. & Zhao, W. Z. Research progress on salt-alkali tolerance mechanism of annual halophytes. J. Gansu Agric. Univ. 54 , 10–22 (2019).

Shu, S., Yuan, L. Y., Guo, S. R., Sun, J. & Liu, C. J. Effects of exogenous spermidine on photosynthesis, xanthophyll cycle and endogenous polyamines in cucumber seedlings exposed to salinity. Afr. J. Biotechnol. 11 , 6064–6074 (2014).

Wang, Y. N. et al. Physiological adaptive strategies of oil seed crop ricinus communis early seedlings (cotyledon vs. true leaf) under salt and alkali stresses: From the growth, photosynthesis and chlorophyll fluorescence. Other 9 , 1939–1952 (2018).

Jia, L., Liu, Y. Q. & Jing, L. I. Effects of alkali stress on Prunus davidiana (Carr.) leaf morphological structure and photosynthetic characteristics. Southwest China J. Agric. Sci. 30 , 327–332 (2017).

Zhang, T. et al. Responses of growth and hotosynthesis of Lycium barbarum L. seedling to Salt-stress and alkali-stress. Acta Bot. Boreali-Occidentalia Sin. 12 , 2474–2482 (2017).

Zhang, Y. H. et al. The effects of soil salinity on photosystem II of rice seedlings. J. Irrig. Drain. 41 , 52–60 (2022).

Zhou, J. et al. Integrated analyses of transcriptome and chlorophyll fluorescence characteristics reveal the mechanism underlying saline-alkali stress tolerance in kosteletzkya pentacarpos. Front. Plant Sci. https://doi.org/10.3389/fpls.2022.865572 (2022).

Demmig-Adams, B. & Adams, W. W. The role of xanthophyll cycle carotenoids in the protection of photosynthesis. Trends Plant Sci. 1 , 21–26 (1996).

Melis, A. Solar energy conversion efficiencies in photosynthesis: Minimizing the chlorophyll antennae to maximize efficiency. Plant Sci. 177 , 272–280 (2009).

Ort, D. R., Zhu, X. & Melis, A. Optimizing antenna size to maximize photosynthetic efficiency. Plant Physiol. 155 , 79–85 (2011).

Hichem, H., Naceur, A. E. & Mounir, D. Effects of salt stress on photosynthesis, PS II photochemistry and thermal energy dissipation in leaves of two corn ( Zea mays L.) varieties. Photosynthetica. 47 , 517–526 (2010).

Yuan, J. L., Ma, C., Feng, Y. L., Zhang, J. & Li, Y. J. Response of chlorophyll fluorescence transient in leaves of wheats with different drought resistances to drought stresses and rehydration. Plant Physiol. J. 54 , 1119–1129 (2018).

Lissner, J. R., Schierup, H. H. & Astorga, V. Effect of climate on the salt tolerance of two phragmites australis populations: II diurnal CO 2 exchange and transpiration. Aquat. Bot. 64 , 335–350 (1999).

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This study was jointly supported by grants from the Natural Science Foundation of Hebei Province (17226320D-4).

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Shenqi Qiao, Changming Ma, Hongjiao Li, Yu Zhang, Minghui Zhang, Wenhao Zhao & Bingxiang Liu

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L.B.X., designed the experimental project, provided financial and theoretical support, and offered theoretical and technical support during the experimental process. Q.S.Q., carried out the experimental results according to L.B.X.,'s experimental plan, processed the experimental data and wrote the paper. M.C.M., and L.H.J., provided theoretical support and offered valuable comments while writing the paper. Z.Y., Z.M.H., and Z.W.H., participated in the whole experiment process according to L.B.X.,'s experimental design.

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Qiao, S., Ma, C., Li, H. et al. Responses of growth and photosynthesis to alkaline stress in three willow species. Sci Rep 14 , 14672 (2024). https://doi.org/10.1038/s41598-024-65004-5

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concentration effect on rate of reaction experiment

Preparation and properties of ammonium polyphosphate/montmorillonite (APP/MMT) polymer, coal spontaneous combustion inhibitor

  • Published: 19 June 2024

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concentration effect on rate of reaction experiment

  • Dexin Xu 1 ,
  • Lanjun Zhang 1 ,
  • Wenjing He 1 ,
  • Hongming Zhang 1 ,
  • Jing Zhu 1 ,
  • Yujia Han 1 ,
  • Yulong Xu 1 ,
  • Shun Hu 1 &
  • Zhiqiang Liu 1  

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As a primary global energy source, coal mining and usage face the threat of spontaneous combustion disasters. Therefore, it is crucial to conduct research on novel retarders for coal spontaneous combustion in order to effectively prevent and control such incidents. The ammonium polyphosphate/montmorillonite (APP/MMT) polymer, known for its excellent flame-retardant properties in material science, has yet to be explored in the context of coal spontaneous combustion. In this study, various ratios of APP/MMT composite inhibitors were prepared using the in situ polymerization approach. The structures of the synthesized inhibitors were examined and compared through scanning electron microscopy, X-ray diffractometer, Fourier infrared spectroscopy (FTIR), and thermal analyzer (TG). Based on the findings, all produced compounds exhibited type I APP/MMT characteristics. By incorporating an appropriate quantity of MMT, both structural integrity and thermal stability could be enhanced. Optimal structural and thermal properties were observed with 3% MMT addition. The TG-DSC thermal analysis experiment instrument, low-temperature oxidation experiment instrument, FTIR infrared spectroscopy instrument, and electron spin resonance instrument (EPR) were employed to investigate the spontaneous combustion characteristics of raw samples and those inhibited samples. The findings indicate that these inhibitors substantially diminish heat release during the coal oxidation process and inhibit CO gas production. They also significantly affect free radical parameters such as g-factor line width and concentration Ng within the samples. Notably, the 3% MMT formulation achieved an inhibition rate of up to 77%, demonstrating its superior effectiveness. Furthermore, an investigation into the mechanism of the inhibitor on coal spontaneous combustion reveals that APP/MMT readily decomposes and generates highly active free radicals such as PO·. These radicals rapidly react with oxygen, effectively obstructing coal-oxygen contact. This research demonstrates that APP/MMT polymer inhibitor exhibits a favorable efficacy and promising application potential in the prevention of coal spontaneous combustion.

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Liu H, Li Z, Li J, Yang Y, Zhang Y. Co-based early warning threshold for coal spontaneous combustion. Mater Chem Phys. 2024;313:128730. https://doi.org/10.1016/j.matchemphys.2023.128730 .

Article   CAS   Google Scholar  

Kong B, Li Z, Yang Y, Liu Z, Yan D. A review on the mechanism, risk evaluation, and prevention of coal spontaneous combustion in china. Environ Sci Pollut Res Int. 2017;24(30):23453–70. https://doi.org/10.1007/s11356-017-0209-6 .

Article   PubMed   Google Scholar  

Zhong Y, Yang S, Hu X, Cai J, Tang Z, Xu Q. Whole process inhibition of a composite superabsorbent polymer-based antioxidant on coal spontaneous combustion. Arab J Sci Eng (2011). 2018;43(11):5999–6009. https://doi.org/10.1007/s13369-018-3167-5 .

Zhou F, Ren W, Wang D, Song T, Li X, Zhang Y. Application of three-phase foam to fight an extraordinarily serious coal mine fire. Int J Coal Geol. 2006;67(1):95–100. https://doi.org/10.1016/j.coal.2005.09.006 .

Liu P, Li Z, Zhang X, Li J, Miao G, Cao S, et al. Study on the inhibition effect of citric acid on coal spontaneous combustion. Fuel (London). 2022;310:122268. https://doi.org/10.1016/j.fuel.2021.122268 .

Lu W, Sun X, Gao L, Hu X, Song H, Kong B. Study on the characteristics and mechanism of dl-malic acid in inhibiting spontaneous combustion of lignite and bituminous coal. Fuel (London). 2022;308:122012. https://doi.org/10.1016/j.fuel.2021.122012 .

Onifade M, Genc B. A review of research on spontaneous combustion of coal. Int J Min Sci Technol. 2020;30(3):303–11. https://doi.org/10.1016/j.ijmst.2020.03.001 .

Gao A, Sun Y, Hu X, Song S, Lu W, Liang Y, et al. Substituent positions and types for the inhibitory effects of phenolic inhibitors in coal spontaneous combustion. Fuel (London). 2022;309:122104. https://doi.org/10.1016/j.fuel.2021.122104 .

Xiao Y, Zhang H, Liu K, Shu C. Macrocharacteristics and the inhibiting effect of coal spontaneous combustion with various treatment durations of ionic liquids. Thermochim Acta. 2021;703:179012. https://doi.org/10.1016/j.tca.2021.179012 .

Xue D, Hu X, Dong H, Cheng W, Wang W, Liang Y. Examination of characteristics of anti-oxidation compound inhibitor for preventing the spontaneous combustion of coal. Fuel (London). 2022;310:122160. https://doi.org/10.1016/j.fuel.2021.122160 .

Yan B, Hu X, Cheng W, Zhao Y, Wang W, Liang Y, et al. A novel intumescent flame-retardant to inhibit the spontaneous combustion of coal. Fuel (Guildford). 2021;297:120768. https://doi.org/10.1016/j.fuel.2021.120768 .

Deng J, Yi Y, Zhang Y. Inhibiting effects of three commercial inhibitors in spontaneous coal combustion. Energy. 2018;160:1174–85.

Li Q, Xiao Y, Zhong K, Shu C, Lü H, Deng J, et al. Overview of commonly used materials for coal spontaneous combustion prevention. Fuel (London). 2020;275:117981. https://doi.org/10.1016/j.fuel.2020.117981 .

Demir H, Arkış E, Balköse D, Ülkü S. Synergistic effect of natural zeolites on flame retardant additives. Polym Degrad Stab. 2005;89(3):478–83. https://doi.org/10.1016/j.polymdegradstab.2005.01.028 .

Xie M, He J, Li X, Yang R. Ammonium polyphosphate/montmorillonite nanocomposite with a completely exfoliated structure and charring–foaming agent flame retardant thermoplastic polyurethane. Mater Sci Eng B Solid-State Mater Adv Technol. 2022;283:115825. https://doi.org/10.1016/j.mseb.2022.115825 .

Tu Z, Ou H, Ran Y, Xue H, Zhu F. Preparation and flame retardant properties of organic montmorillonite synergistic intumescent flame retardant polypropylene. J Loss Prev Process Ind. 2024;87:105226. https://doi.org/10.1016/j.jlp.2023.105226 .

Basnayake AP, Hidalgo JP, Heitzmann MT. A flammability study of aluminium hydroxide (ath) and ammonium polyphosphate (app) used with hemp/epoxy composites. Constr Build Mater. 2021;304:124540. https://doi.org/10.1016/j.conbuildmat.2021.124540 .

Lin J, Liu Y, Wang D, Qin Q, Wang Y. Poly(vinyl alcohol)/ammonium polyphosphate systems improved simultaneously both fire retardancy and mechanical properties by montmorillonite. Ind Eng Chem Res. 2011;50(17):9998–10005. https://doi.org/10.1021/ie100674s .

Yi D, Yang R, Wilkie CA. Full scale nanocomposites: clay in fire retardant and polymer. Polym Degrad Stab. 2014;105:31–41. https://doi.org/10.1016/j.polymdegradstab.2014.03.042 .

Yinping D, Zhiyuan Z, Xiangmei L, Yongjie Y. The effects of app, app/mmt nanocomposites on the thermal degradation of abs resin. J Appl Polym Sci. 2014;131(17):8697–704. https://doi.org/10.1002/APP.40704 .

Article   Google Scholar  

Qin P, Yi D, Xing J, Zhou M, Hao J. Study on flame retardancy of ammonium polyphosphate/montmorillonite nanocompound coated cellulose paper and its application as surface flame retarded treatment for polypropylene. J Therm Anal Calorim. 2021;146(5):2015–25. https://doi.org/10.1007/s10973-020-10427-1 .

Hanna AA, Nour MA, Souaya ER, Sherief MA, Abdelmoaty AS. Studies on the flammability of polypropylene/ammonium polyphosphate and montmorillonite. Open Chem. 2018;16:108–15.

Yi D, Yang R. Ammonium polyphosphate/montmorillonite nanocompounds in polypropylene. J Appl Polym Sci. 2010;118(2):834–40. https://doi.org/10.1002/app.32362 .

Zheng H, Li Y, Zhang L, He W, Han Y, Xu D. Study on the effect of organic sulfur on coal spontaneous combustion based on model compounds. Fuel (London). 2021;289:119846. https://doi.org/10.1016/j.fuel.2020.119846 .

Butuzova L, Makovskyi R, Budinova T, Marinov SP. Epr and ir studies on the role of coal genetic type in plastic layer formation. Fuel Process Technol. 2014;125:246–50. https://doi.org/10.1016/j.fuproc.2014.04.008 .

Liu J, Jiang X, Shen J, Zhang H. Chemical properties of superfine pulverized coal particles. Part 1. Electron paramagnetic resonance analysis of free radical characteristics. Adv Powder Technol Int J Soc Powder Technol Jpn. 2014;25(3):916–25. https://doi.org/10.1016/j.apt.2014.01.021 .

Zhao T, Yang S, Hu X, Song W, Cai J, Xu Q. Restraining effect of nitrogen on coal oxidation in different stages: non-isothermal tg-dsc and epr research. Int J Min Sci Technol. 2020;30(3):387–95. https://doi.org/10.1016/j.ijmst.2020.04.008 .

Zhou Q, Luo Z, Li G, Li S. Epr detection of key radicals during coking process of lignin monomer pyrolysis. J Anal Appl Pyrolysis. 2020;152:104948. https://doi.org/10.1016/j.jaap.2020.104948 .

Xu D, Zhang L, He W, Xu Y, Zhao Y, Zhu J, et al. The generation mechanism of co and co 2 in coal spontaneous combustion by mathematical statistical and other methods. Fuel (London). 2023;350:128747. https://doi.org/10.1016/j.fuel.2023.128747 .

Zhao J, Wang W, Fu P, Wang J, Gao F. Evaluation of the spontaneous combustion of soaked coal based on a temperature-programmed test system and in-situ ftir. Fuel (London). 2021;294:120583. https://doi.org/10.1016/j.fuel.2021.120583 .

Bee ST, Lim KS, Sin LT, Ratnam CT, Bee SL, Rahmat AR. Interactive effect of ammonium polyphosphate and montmorillonite on enhancing flame retardancy of polycarbonate/acrylonitrile butadiene styrene composites. Iran Polym J. 2018;27(11):899–911. https://doi.org/10.1007/s13726-018-0664-z .

Beher D, Hesse L, Masters CL, Multhaup G. Regulation of amyloid protein precursor (app) binding to collagen and mapping of the binding sites on app and collagen type i (∗). J Biol Chem. 1996;271(3):1613–20. https://doi.org/10.1074/jbc.271.3.1613 .

Article   CAS   PubMed   Google Scholar  

Zhang J, Liang Z, Liu J, Wan Y, Tao X, Zhang H, et al. Preparation and performance analysis of palygorskite reinforced silicone-acrylic emulsion-based intumescent coating. Prog Org Coat. 2022;166:106801. https://doi.org/10.1016/j.porgcoat.2022.106801 .

Liang Y, Zhang J, Wang L, Luo H, Ren T. Forecasting spontaneous combustion of coal in underground coal mines by index gases: a review. J Loss Prev Process Ind. 2019;57:208–22. https://doi.org/10.1016/j.jlp.2018.12.003 .

Zhang D, Cen X, Wen H, Wang H, Deng J, Tang R, et al. Effect of particle size on co adsorption and thermodynamic analysis. J Loss Prev Process Ind. 2023;84:105127. https://doi.org/10.1016/j.jlp.2023.105127 .

Dou G, Liu J, Jiang Z, Jian H, Zhong X. Preparation and characterization of a lignin based hydrogel inhibitor on coal spontaneous combustion. Fuel (London). 2022;308:122074. https://doi.org/10.1016/j.fuel.2021.122074 .

Kumar Mohalik N, Mandal S, Kumar Ray S, Mobin Khan A, Mishra D, Krishna PJ. Tga/dsc study to characterise and classify coal seams conforming to susceptibility towards spontaneous combustion. Int J Min Sci Technol. 2022;32(1):75–88. https://doi.org/10.1016/j.ijmst.2021.12.002 .

Zhang X, Zou J, Lu B, Huang G, Yu C, Liang H. Experimental study on effect of mudstone on spontaneous combustion of coal. Energy (Oxford). 2023;285:128784. https://doi.org/10.1016/j.energy.2023.128784 .

Liu L, Zhang H, Sun L, Kong Q, Zhang J. Flame-retardant effect of montmorillonite intercalation iron compounds in polypropylene/aluminum hydroxide composites system. J Therm Anal Calorim. 2016;124(2):807–14. https://doi.org/10.1007/s10973-015-5213-9 .

Li Z, Li Y, Shen Y, Yu T, Wang J. Synergic effects of dimethyl methylphosphonate (dmmp) and nano-sized montmorillonite (mmt) on the flammability and mechanical properties of flax fiber reinforced phenolic composites under hydrothermal aging. Compos Sci Technol. 2022;230:109487. https://doi.org/10.1016/j.compscitech.2022.109487 .

Sadashiv Todkar S, Abasaheb PS. Creep and heat deflection temperature (hdt) study of pineapple leaf fibre (palf) and montmorillonite (mmt) nanoclay reinforced poly-lactic acid (pla) based laminated hybrid biocomposite. Mater Today Proce. 2022;62:7534–9. https://doi.org/10.1016/j.matpr.2022.04.343 .

Sengwa RJ, Dhatarwal P. Toward multifunctionality of peo/pmma/mmt hybrid polymer nanocomposites: promising morphological, nanostructural, thermal, broadband dielectric, and optical properties. J Phys Chem Solids. 2022;166:110708. https://doi.org/10.1016/j.jpcs.2022.110708 .

Li J, Lu W, Li J, Yang Y, Li Z. Towards understanding of internal mechanism of coal reactivity enhancement after thermal decomposition at low temperature. Fuel (London). 2023;337:127118. https://doi.org/10.1016/j.fuel.2022.127118 .

Lu H, Li J, Lu W, Xu Z, Li J, He Q. Variation laws of co2/co and influence of key active groups on it during low-temperature oxidation of coal. Fuel (London). 2023;339:127415. https://doi.org/10.1016/j.fuel.2023.127415 .

Chen L, Qi X, Tang J, Xin H, Liang Z. Reaction pathways and cyclic chain model of free radicals during coal spontaneous combustion. Fuel (London). 2021;293:120436. https://doi.org/10.1016/j.fuel.2021.120436 .

Oyarzún A, García X, Radovic L. Irc data for a mechanistic route starting with h2o adsorption and finishing with h2 desorption from graphene. Data Brief. 2020;30:105362. https://doi.org/10.1016/j.dib.2020.105362 .

Article   CAS   PubMed   PubMed Central   Google Scholar  

Feng L, Dong M, Qin B. Effect of microwave pretreatment on oxidization behaviors of bituminous coal: experimental measurement and quantum chemistry calculation. Fuel (Guildford). 2023;344:128040. https://doi.org/10.1016/j.fuel.2023.128040 .

Download references

Acknowledgements

This work was supported by the National Natural Science Foundation of China (Nos. 52004104, 21606095, 22208132), the National Natural Science Foundation of China: Controllable synthesis and structure-activity relationship of layered assembly of graphene-based composite energy storage materials, Jiangsu Province Graduate Research, Practice Innovation Program (No. KYCX2023-73), and Qinglan Project of Jiangsu Province.

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School of Environment and Chemical Engineering, Jiangsu Ocean University, Lianyungang, 222005, China

Dexin Xu, Lanjun Zhang, Wenjing He, Hongming Zhang, Jing Zhu, Yujia Han, Yulong Xu, Shun Hu & Zhiqiang Liu

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Xu, D., Zhang, L., He, W. et al. Preparation and properties of ammonium polyphosphate/montmorillonite (APP/MMT) polymer, coal spontaneous combustion inhibitor. J Therm Anal Calorim (2024). https://doi.org/10.1007/s10973-024-13340-z

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Received : 28 October 2023

Accepted : 22 May 2024

Published : 19 June 2024

DOI : https://doi.org/10.1007/s10973-024-13340-z

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IMAGES

  1. Lab #27: The Effect of Concentration on Reaction Rate Purpose

    concentration effect on rate of reaction experiment

  2. Factors Affecting Reaction Rate

    concentration effect on rate of reaction experiment

  3. Factors that Affect Rate of Reaction

    concentration effect on rate of reaction experiment

  4. Explain the effect of concentration on the rate of reaction?

    concentration effect on rate of reaction experiment

  5. Rate of reaction & concentration.

    concentration effect on rate of reaction experiment

  6. Lab Experiment #19: Effect of Concentration on the Reaction Rate

    concentration effect on rate of reaction experiment

VIDEO

  1. CHEMISTRY s6: Effect of concentration on the rate of chemical reactions

  2. Factors Affecting Reaction Rates Lab

  3. Concentration Effect on Rate of Reaction

  4. Effect of Temperature on Rate of reaction|| Reaction Kinetics| # factors affecting rate of reaction

  5. Concentration-Time Graphs. Y13 A-level Chemistry OCR AQA: Reaction Rates Kinetics

  6. experiment to show how concentration affects the rate of reaction PART 1

COMMENTS

  1. 14.3: Effect of Concentration on Reaction Rates: The Rate Law

    For each reaction, give the units of the rate constant, give the reaction order with respect to each reactant, give the overall reaction order, and predict what happens to the reaction rate when the concentration of the first species in each chemical equation is doubled. 2HI(g) Pt → H2(g) + I2(g)rate = − 1 2 (Δ [ HI] Δt) = k[HI]2.

  2. The effect of concentration on reaction rate

    Calculate the concentration of sodium thiosulfate in the flask at the start of each experiment. Record the results in the table provided on the student sheet. For each set of results, calculate the value of 1/time. (This value can be taken as a measure of the rate of reaction). Plot a graph of 1/time taken on the vertical (y) axis and ...

  3. 14.4: Effect of Concentration on Reaction Rate

    The Rate Law is a power function that describes the effect of the concentration of the reactants on the rate of reaction for a reaction occurring at constant temperature. If there is only one reactant it has the form of. A → Products R = k[A]m (14.4.1) (14.4.1) A → P r o d u c t s R = k [ A] m.

  4. Required Practical: Investigating the Effect of Concentration on Rate

    To investigate the effect of changing concentration on the rate of reaction by measuring the volume of gas given off. Hypothesis: The same amount of gas will be produced in less time if the concentration of reactants is increased. Materials: Magnesium ribbon cut into 3 cm lengths; Sulfuric acid 1 mol/dm 3 and 1.5 mol/dm 3; Conical flask (100 cm ...

  5. THE EFFECT OF CONCENTRATION ON REACTION RATES

    In a few cases, increasing the concentration of one of the reactants may have little noticeable effect of the rate. These cases are discussed and explained further down this page. Don't assume that if you double the concentration of one of the reactants that you will double the rate of the reaction. It may happen like that, but the relationship ...

  6. 14.3: Concentration and Rates (Differential Rate Laws)

    The general rate law for the reaction is given in Equation 14.3.12. We can obtain m or n directly by using a proportion of the rate laws for two experiments in which the concentration of one reactant is the same, such as Experiments 1 and 3 in Table 14.3.3. rate1 rate3 = k[A1]m[B1]n k[A3]m[B3]n.

  7. PDF The Effect of Temperature and Concentration on Reaction Rate

    CLOCK REACTION . In this experiment, the effect of temperature and concentration on the rate of a chemical reaction will be studied. The reaction chosen, frequently termed the "clock reaction", is actually a series of consecutive reactions represented by the following equations: BrO 3 1-1+ 6 I - + 6H+ Br1-+ 3I 2 + 3 H 2O (1) -I 2 + 2 S 2O 3

  8. The effect of concentration and temperature on reaction rate

    Explore the effect that concentration and temperature have on the reaction time of chemicals with this experiment in kinetics. In this experiment, two colourless solutions are mixed to make a solution which becomes dark blue. Changing the concentration or temperature of the solutions changes the time required for the blue colour to develop.

  9. Reactions & Rates

    We recommend using the latest version of Chrome, Firefox, Safari, or Edge. Explore what makes a reaction happen by colliding atoms and molecules. Design experiments with different reactions, concentrations, and temperatures. When are reactions reversible? What affects the rate of a reaction?

  10. Rates of reaction: observing a colour change

    Video and resources showing how the concentration of sodium thiosulfate solution affects its rate of reaction with hydrochloric acid. Investigate rates of reaction (observing a colour change) with GCSE, Junior Cycle and National 5 learners using this practical video, using this video, including a step-by-step method, calculation support for ...

  11. Lesson Explainer: Effects of Temperature and Concentration on Rates of

    The rate of a chemical reaction can be affected by many factors. By changing some of these factors, the rate of reaction can be increased or decreased. The factors that affect the rate of reaction include surface area, temperature, concentration, and the addition of catalysts. We will focus on temperature and concentration.

  12. Effect of concentration on rates of reaction

    A more detailed experiment. A commonly used experiment to show the effect of concentration on rate is between dilute hydrochloric acid and sodium thiosulfate solution. Na 2 S 2 O 3 (aq) + 2HCl (aq) 2NaCl (aq) + SO 2 (g) + S (s) + H 2 O (l) At this stage, the only place you are likely to come across sodium thiosulfate is in this reaction.

  13. PDF The effect of concentration on rate

    2 Information about the effect of changes of concentration on the rates of some reactions is given below. For each example, use the information to write the rate equation for the reaction. a. The rate is proportional to the concentration of cyclopropene. b →2N 2O(g) 2N 2(g) + O 2(g) The rate is proportional to the concentration of nitrogen(I ...

  14. 2.3.10 Practical: Investigating the Effect Enzyme and Substrate

    Substrate concentration. Substrate concentration affects the rate of reaction; The higher the substrate concentration the faster the rate of reaction; More substrate molecules means more collision between enzyme and substrate so the more likely an active site will be used by a substrate; The is only the case up until a certain concentration of substrate, at which point a saturation point is ...

  15. Investigating the Effect of Concentration on Reaction Time

    2) A stock solution of 0.15 M Na2S2O3 is used to make 5 different concentrations using different amounts of distilled water, though our tap water worked just fine too. The total volume of each solution should be the same in each beaker. 3) Add 5 mL of 2 M HCl to your first beaker to start the reaction. You can give it an initial stir to ...

  16. Investigating The Rate of a Reaction

    Investigating the effect of concentration of a solution on the rate of reaction. Diagram showing the apparatus needed to investigate the effect of concentration on the rate of reaction Method: Measure 50 cm 3 of sodium thiosulfate solution into a flask; Measure 5 cm 3 of dilute hydrochloric acid into a measuring cylinder

  17. The rate of reaction of magnesium with hydrochloric acid

    Mg (s) + 2HCl (aq) → MgCl 2 (aq) + H 2 (g) Students follow the rate of reaction between magnesium and the acid, by measuring the amount of gas produced at 10 second intervals. 3 cm of magnesium ribbon typically has a mass of 0.04 g and yields 40 cm 3 of hydrogen when reacted with excess acid. 50 cm 3 of 1M hydrochloric acid is a six-fold ...

  18. PDF The Effect of Temperature and Concentration on Reaction Rate

    CLOCK REACTION In this experiment, the effect of temperature and concentration on the rate of a chemical reaction will be studied. The reaction chosen, frequently termed the "clock reaction", is actually a series of consecutive reactions represented by the following equations: HIO 3 + 3 Na 2SO 3 _ HI + 3 Na 2SO 4 (1) HIO 3 + 5 HI _ 3 H

  19. Rates of reaction

    Temperature, reactant concentration, size of solid reactant particles (surface area) and catalysts can all affect the reaction rate. Part of Combined Science Further chemical reactions, rates and ...

  20. Experiment 2

    EXPERIMENT 2: Effect of Concentration on the Rate of Reaction of Sodium Thiosulphate with Hydrochloric Acid Objectives. To determine the rate of reaction in between sodium thiosulphate with hydrochloric acid. To determine order of reaction. Introduction. A rate of reaction is defined as how fast or slow a reaction takes place.

  21. 19.5: Effect of Concentration on Enzyme Activity

    The excess substrate molecules cannot react until the substrate already bound to the enzymes has reacted and been released (or been released without reacting). Figure 19.5.1 19.5. 1: Concentration versus Reaction Rate. (a) This graph shows the effect of substrate concentration on the rate of a reaction that is catalyzed by a fixed amount of ...

  22. Enhanced Removal of River‐Borne Nitrate in Bioturbated Hyporheic Zone

    3.1 Effects of Bioturbation on Spatial Distribution of Nutrients Concentration and Reaction Rates 3.1.1 Sediment Reworking The findings indicate that the interaction between stream boundary layer flow and fecal mounds generates a horizontal pressure gradient at the SWI (Figure 1a , F).

  23. Rate experiments

    Core practical 7.1. Investigate the effects of changing the conditions of a reaction on the rates of chemical reactions by: a) measuring the production of a gas (in the reaction between hydrochloric acid and marble chips) b) observing a colour change (in the reaction between sodium thiosulfate and hydrochloric acid) OCR GCSE (9-1) Gateway ...

  24. Responses of growth and photosynthesis to alkaline stress in three

    The net photosynthetic rate (Pn), rate of transpiration (E), and stomatal conductance (Gs) of the leaves showed a general trend of decreasing, and the intercellular CO2 concentration (Ci) of S ...

  25. 6.2 The Effect of Concentration on Reaction Rate

    A Comparing Experiments 1 and 2 shows that as [O 2] is doubled at a constant value of [NO 2], the reaction rate approximately doubles. Thus the reaction rate is proportional to [O 2] 1, so the reaction is first order in O 2. Comparing Experiments 1 and 3 shows that the reaction rate essentially quadruples when [NO] is doubled and [O 2] is

  26. Preparation and properties of ammonium polyphosphate ...

    Additionally, according to the ESR experiment, it is found that the inhibitor effectively reduces the concentration of free radicals in coal and suppresses oxygen-free radical reactions. To gain the microscopic inhibition mechanism, Gaussian 16 software and density functional theory (DFT) were utilized based on previous research.