Home Store Project Ideas Project Guide Ask An Expert Blog Careers Teachers Parents Students
Create Assignment

Minds of Their Own: A Chemical Reaction that Changes, then Changes Back!

google science journal chemical reaction summary  
Do this Science
Project with Your
Phone!
works with google science journal app
Difficulty
Time Required Long (2-4 weeks)
Prerequisites A class in chemistry would be helpful, but is not required.
Material Availability You will need to order the Oscillating Chemical Reaction Kit online. See the Materials and Equipment list for details.
Cost Average ($50 - $100)
Safety Adult supervision is required. Minor injury is possible. Be sure to wear safety goggles.

Abstract

Have you ever seen a chemical reaction that makes a solution change color? Probably. But what about a solution that changes color and then changes back, not only once, but many times? Sounds pretty exotic! Whereas most chemical reactions only move in one direction from reactants (starting chemicals) to products, in these rare oscillating reactions, the reaction products appear and disappear for a number of cycles. Because the products are colored, the solution appears alternately blue, then yellow, then clear. In this science project, you can even record each cycle of color change using Google's Science Journal app. The reaction is easy to set up and fun to watch—so what are you waiting for?

Objective

Explore factors that control an oscillating chemical reaction.

Credits

David B. Whyte, PhD, Science Buddies
Edited by Svenja Lohner, PhD, Science Buddies

Cite This Page

MLA Style

Science Buddies Staff. "Minds of Their Own: A Chemical Reaction that Changes, then Changes Back!" Science Buddies. Science Buddies, 28 July 2017. Web. 16 Dec. 2017 <https://www.sciencebuddies.org/science-fair-projects/project-ideas/Chem_p097/chemistry/chemical-reaction-that-changes-color>

APA Style

Science Buddies Staff. (2017, July 28). Minds of Their Own: A Chemical Reaction that Changes, then Changes Back!. Retrieved December 16, 2017 from https://www.sciencebuddies.org/science-fair-projects/project-ideas/Chem_p097/chemistry/chemical-reaction-that-changes-color

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.


Last edit date: 2017-07-28

Introduction

What do these things have in common: rust forming on an iron nail, a mixture of vinegar and baking soda producing carbon dioxide bubbles, and gasoline burning in a car's engine? They are all examples of chemical reactions. In each example, the starting chemicals, or reactants, combine to form the resulting chemicals, or products. Rust (or iron oxide) forms when iron in the metal combines with oxygen in the atmosphere. Carbon dioxide forms when the acetic acid in vinegar reacts with sodium bicarbonate in baking soda. And water, carbon dioxide, and the energy used to make a car move result when gasoline reacts with oxygen. These reactions all move in one direction, from reactants to products. However, the Briggs-Rauscher (BR) reaction is different from these reactions in that it oscillates. To start the chemical reaction, two clear solutions are mixed together.


Watch this video of Briggs-Rauscher oscillating reaction.
Watch this video of Briggs-Rauscher oscillating reaction. https://www.youtube.com/watch?v=EKTjxxL0kjo

The resulting clear solution then turns blue, then yellow, and then clear again. Each color is present for about 1–3 seconds (sec). The cycle of color changes repeats until one or more of the chemicals are used up. The reaction was developed by Thomas S. Briggs and Warren C. Rauscher of Galileo High School in San Francisco in 1972.

Don't let the equations below scare you away! Don't worry if you think you'll find the following chemistry explanations and chemical equations a bit intimidating—most professional chemists would agree that the chemistry of the Briggs-Rauscher reaction is complicated! While you will not need to use the following equations to perform the experiment below, the information is included so you can try to learn and understand the reactions taking place. There are a lot of things going on at the molecular level to create the oscillating color changes. However, this science project has the advantage that you can actually see changes in the reaction products (the colored ones, at least) as they form and disappear. You can even record the color changes with a light sensor! This science project focuses on how changing the concentration of one of the chemicals (malonic acid) affects the color changes in the reaction. Do you think the color change will happen faster or slower if you add more chemicals?

The following explanation of the chemistry involved in the reaction is based on the University of Leeds chemistry website and Shakhashiri's book (see the Bibliography). In the BR reaction, the evolution of oxygen and carbon dioxide gases and the concentrations of iodine and iodide ions oscillate. Here is the list of names for the chemicals in the reactions that follow:

  • IO3-: Iodate ion, from sodium iodate
  • H2O2: Hydrogen peroxide
  • CH2(COOH)2: Malonic acid
  • H+: Hydrogen ion
  • ICH(COOH)2: Iodomalonic acid
  • O2: Oxygen
  • H2O: Water
  • HIO: Hypoiodous acid
  • I-: Iodide ion
  • HIO2: Iodous acid
  • Mn2+: Manganese ion, from manganese sulfate
  • Mn(OH)2: Manganese dioxide
  • HOO.: Hydroperoxyl radical
  • IO2.: Iodide dioxide radical

The mechanism of this reaction can be summarized by the following equations:

Equation 1:
IO3- + 2 H2O2 + CH2(COOH)2 + H+ → ICH(COOH)2 + 2 O2 + 3 H2O

This transformation can be represented by two component reactions:

Equation 2:
IO3- + 2 H2O2 + H+ → HIO + 2 O2 + 2 H2O
Equation 3:
HIO + CH2(COOH)2 → ICH(COOH)2 + H2O

The first of these two reactions can occur by either of two different processes, a radical process and a non-radical process (radicals are atoms, molecules, or ions with unpaired electrons, represented as a dot after the name, as in HOO., the hydroperoxyl radical). These two component reactions "compete" for dominance, and the processes that dominates is determined by the concentration of iodide ions in the solution. When [I-] is low, the reaction proceeds primarily by the radical process; when [I-] is high, the non-radical process is the major process. The second reaction (Equation 3) couples the two processes. The reaction consumes HIO more slowly than HIO is produced by the radical process when that process is predominant, but it uses up HIO more rapidly than it is produced by the non-radical process. Any HIO that does not react by Equation 3 is reduced to I- by hydrogen peroxide as one of the component steps of the non-radical process for reaction 2.

When HIO is produced rapidly by the radical process, the excess forms the iodide ions, which shut off that radical process and start the slower non-radical process. Reaction 3 then consumes the HIO so rapidly that not enough is available to produce the iodide ion necessary to keep the nonradical process going, and the radical process starts again. Each of the processes of reaction 2 produces conditions favorable to the other process; therefore, the reaction oscillates between these two processes.

Let's look at the process in a little more detail. If iodide ions are present in sufficient concentration, the reaction follows the non-radical process, reaction 2. The iodide ions react relatively slowly with iodate ions.

Equation 4:
IO3- + I- + 2 H+ → HIO2 + HIO

The iodous acid (HIO2) is further reduced to hypoiodous acid (HIO).

Equation 5:
HIO2 + I- + H+ → 2 HIO

The hypoiodous acid is then reduced by hydrogen peroxide.

Equation 6:
HIO + H2O2 → I- + O2 + H+ + H2O

The net transformation, represented by Equation 2, is obtained by the stoichiometric addition of Equation 4 + Equation 5 + Equation 6.

Because reaction 2 is slower than reaction 3 under these conditions, so much HIO is used up by reaction 3 that reaction 6 cannot replenish the I- consumed in reactions 4 and 5; the [I-] keeps diminishing.

Once the concentration of iodide ions falls below a certain level, the non-radical process becomes very slow, and the radical process for reaction 2 takes over. This process involves these five steps:

Equation 7:
IO3- + HIO2 + H+ → 2 IO2· + H2O
Equation 8:
IO2· + Mn2++ H2O → HIO2 + Mn(OH)2
Equation 9:
Mn(OH)2 + H2 O2 → Mn2+ + H2O + HOO·
Equation 10:
2 HOO· → H2O2 + O2
Equation 11:
2 HIO2 → IO3- + HIO + H+

These steps, when combined in the stoichiometry of 2 (Equation 7) + 4 (Equation 8) + 4 (Equation 9) + 2 (Equation 10) +1 (Equation 11), have the overall result given by Equation 2. A significant feature of this process is that, taken together, the first two steps, Equation 7 and Equation 8, are autocatalytic—they produce 2 HIO2 for each one consumed. Therefore, the rate of these steps increases as they occur. Because this radical process is autocatalytic, it causes a rapid increase in the concentration of HIO, which is produced by the disproportionation of HIO2 (Equation 11). This process does not rapidly consume all the iodate in the solution, because the last step is second order in the catalytic species. Thus, as its concentration increases because of the autocatalytic nature of the early steps, HIO2 is ever more rapidly consumed in this last step, and the sequence of the reactions quickly reaches a steady state.

Equations 8 and 9 show the function of the manganese catalyst. The manganese is oxidized in reaction 8 and reduced in reaction 9. Its catalytic effect in the reaction is accounted for through its providing the means for reducing IO2· radicals to HIO2, thereby completing the autocatalytic cycle of equations 7 and 8.

The hypoiodous acid produced by the radical process reacts with malonic acid by reaction 3. However, the radical process is faster than reaction 3, and the excess HIO reacts with hydrogen peroxide by reaction 6 to create I-, which shuts off the radical process and returns the system to the slow nonradical process initiated by reaction 4.

The dramatic color effects arise because reaction 3 does not take place in a single step, but by the sequence of reactions 12 and 13.

Equation 12:
I- + HIO + H+ → I2 + H2O
Equation 13:
I2 + CH2(COOH)2 → ICH(COOH)2 + H+ + I-

The solution turns amber from the I2 produced through reaction 1, when the radical process maintains [HIO] greater than [I-]. The excess HIO is converted to I- through the reaction with H2O2 (Equation 6). The solution suddenly turns dark blue when [I-] becomes greater than [HIO], and the I- can combine with I2 to form a complex with the starch. With [I-] high, reaction 2 switches to the slow nonradical process. The color then fades as reaction 3 consumes iodine faster than it is produced. When the system switches back to the rapid radical process, the cycle repeats.

When the solutions containing the reactants are mixed, IO3- reacts with H2O2 to produce a little HIO2. The HIO2 reacts with IO3- in the first step of the radical process (Equation 7). The autocatalytic radical process follows, rapidly increasing the concentration of HIO. The HIO is reduced to I- in a reaction with H2O2 (Equation 6). The large amount of HIO reacts with I-, producing I2 (Equation 12). The I2 reacts slowly with malonic acid, but the concentration of HIO, I2- all increase, because reaction 2 is faster than reaction 3. As [I-] increases, the rate of its reaction with HIO2 (Equation 5) surpasses that of the autocatalytic sequence of reactions 7 and 8. The radical process is then shut off, and the accumulation of reduced iodine is consumed by reaction 3 operating through the sequence of reactions 12 and 13. Eventually, [I-] is reduced to such a low value that reactions 7 and 8 become faster than reaction 5, and the radical process takes over again. This oscillating sequence repeats until the malonic acid or IO3- is depleted.

For this science project, you will buy a kit that contains all of the chemicals you need. Wear gloves and safety goggles when working with chemicals. The focus of the procedure is to investigate how changing the amount of malonic acid affects the color changes produced in the reaction.

Terms and Concepts

  • Chemical reaction
  • Reactant
  • Product
  • Briggs-Rauscher (BR) reaction
  • Oscillate
  • Radical process
  • Stoichiometric addition
  • Stoichiometry
  • Autocatalysis, autocatalytic
  • Disproportionation
  • Steady state
  • Autocatalytic reaction process
  • Catalysis

Questions

  • What is the role of starch in the reaction mix?
  • What chemical causes the yellow color in the reaction?
  • Excess chloride ions interfere with the reaction. Why?

Bibliography

News Feed on This Topic

 
, ,
Note: A computerized matching algorithm suggests the above articles. It's not as smart as you are, and it may occasionally give humorous, ridiculous, or even annoying results! Learn more about the News Feed

Materials and Equipment

  • The Fascinating Oscillating Reaction Kit, Educational Innovations, Inc.; available from www.teachersource.com. The kit comes in two sizes:
    • Item CK-475 has one set of chemicals and provides sufficient chemicals for three trials of the basic procedure.
    • Item CK-480 is a larger classroom kit that has more chemicals. Order the larger kit if you want to have chemicals for variations of the basic procedure. The classroom kit is also available through Carolina Biological Supply Company (item # 840443). Note: If you are ordering this kit through Carolina Biological Supply Company, the kit must be ordered by a teacher and shipped to a school or business address, so plan accordingly.
    • The kit contains the following items:
      • Malonic acid
      • Manganese sulfate
      • Sodium iodate
      • Sodium thiosulfate
      • Sulfamic acid
      • Starch solution
      • Wooden rack
      • Pipet
      • Stirrers
      • Spoon
      • Small scoops
      • Cups
      • Instructions
  • Hydrogen peroxide (3%) is required and not supplied in the kit; it is available from Carolina Biological Supply Company (item # 868093) or at any drug store. Note: If you are ordering this chemical through Carolina Biological Supply Company, the chemical must be ordered by a teacher and shipped to a school or business address, so plan accordingly.
  • Permanent marker
  • Distilled water; available at grocery or drug stores
  • With option 2 in procedure: Stopwatch
  • Lab notebook
  • Adult helper
  • With option 1 in procedure: Flashlight
  • With option 1 in procedure: Tripod, or stand to attach the flashlight to
  • With option 1 in procedure: A smartphone or tablet to record your data
    science-journal-app-icon This project uses Google's Science Journal app, a free app that allows you to gather and record data with a cell phone or tablet. You can download the app from Google Play for Android devices (version 4.4 or newer) or from the App Store for iOS devices (iOS 9.3 or newer).
  • With option 1 in procedure: A transparent, waterproof plastic bag that fits your phone inside

Disclaimer: Science Buddies occasionally provides information (such as part numbers, supplier names, and supplier weblinks) to assist our users in locating specialty items for individual projects. The information is provided solely as a convenience to our users. We do our best to make sure that part numbers and descriptions are accurate when first listed. However, since part numbers do change as items are obsoleted or improved, please send us an email if you run across any parts that are no longer available. We also do our best to make sure that any listed supplier provides prompt, courteous service. Science Buddies does participate in affiliate programs with Amazon.com, Carolina Biological, and Jameco Electronics. Proceeds from the affiliate programs help support Science Buddies, a 501(c)(3) public charity. If you have any comments (positive or negative) related to purchases you've made for science fair projects from recommendations on our site, please let us know. Write to us at scibuddy@sciencebuddies.org.

Remember Your Display Board Supplies

ArtSkills sparkle letters

Holographic Poster Letters

ArtSkills buy now button
ArtSkills vinyl letters

Vinyl Letters & Numbers

ArtSkills buy now button
ArtSkills supplies trifold

ArtSkills Trifold with Header

ArtSkills buy now button

Remember Your Display Board Supplies

Artskills materials poster making kit

Poster Making Kit

ArtSkills buy now button
ArtSkills supplies trifold

ArtSkills Trifold with Header

ArtSkills buy now button
ArtSkills supplies poster lights

Poster Lights

ArtSkills buy now button

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.

Experimental Procedure

Important Notes Before You Begin:

  1. Wear safety goggles and gloves.
  2. Arrange the chemicals in the wooden rack to make them easier to work with.
    1. The chemicals you will need are sodium iodate, sulfamic acid, malonic acid, and manganese sulfate. They are in plastic vials.
    2. You will make enough of the solutions so that you can perform the procedure three times with the original solutions. This prevents variation due to measuring out different amounts of chemicals in separate trials.
    3. You will make an excess of each solution (40 mL rather than 30) so that there is enough to run it three times with an equal amount of liquid. If you make just enough for three trials, the volumes available for the third trial might be less than needed.
  3. You will use the Science Journal app to record each color change with the light sensor of your smartphone. The app creates a graph that will allow you to accurately determine the time in between each color change (the oscillation frequency) as well as the number of color change cycles. If you do not have a phone, you can alternatively observe the reaction and use a stopwatch to time how long it takes for the reaction to turn blue again.

Making the Original Solutions

First, you will prepare solutions A and B with the chemicals shown in Figure 1. The first reaction you prepare will have 4 scoops of malonic acid in solution B. Later in the procedure, you will change this amount to see how the oscillation behavior changes dependent on malonic acid availability in the reaction solution.

rb-solution-chemicals
Figure 1. For the oscillation reaction, you will prepare two different solutions (A and B) and vary the amounts of malonic acid in solution B.

Making Solution A

  1. Label one cup A.
  2. Pour 40 mL of distilled water into cup A using the beaker.
  3. Add two scoops of sodium iodate and four level scoops of sulfamic acid to the cup.
  4. Swirl gently until the chemicals are dissolved.
  5. This is solution A. It should look colorless and clear.

Making Solution B

  1. Label another cup B.
  2. Add 40 mL of hydrogen peroxide to cup B using the beaker.
  3. Add four rounded scoops of malonic acid to cup B.
  4. Add a small amount of manganese sulfate, about the size of a grain of rice.
  5. Shake the starch solution bottle, then add 10 drops of the starch solution to cup B.
  6. Swirl the solution to mix the chemicals.
  7. This is solution B. It should be colorless and clear. You might notice some white flocs floating in solution, which result from the starch being added.

Mixing the Solutions

Before you mix the solutions, you should choose one method to gather your data. If you have a phone available, you can record your data with the Science Journal app. If you do not have a phone, continue with option 2 that uses a stopwatch to time the color change. You can also use both methods in parallel and compare the results at the end.

Option 1: Using the Science Journal app

Science Journal is an app that lets you record data using sensors that are built into many smartphones, including a light sensor which measures light levels (normally this sensor is used to automatically adjust the brightness of your phone's screen). You can learn how to use the Science Journal app here and how to use the light sensor here. In this project, you can use the app to record the color change of your reaction. You will do this by placing your solution directly on top of the light sensor and measuring how much light shines through. You will notice that when the color of your solution becomes darker, less light will reach your light sensor compared to when your solution is colorless.

  1. Protect your phone from any potential spills by putting it into the waterproof plastic bag. Make sure the bag is transparent so light can get through. Lay your phone flat on the table with the display facing upwards.
  2. Make sure you know the location of the light sensor in your phone and test if it works as expected. You can do this by following the steps described here.
  3. Label a third cup C and place it right on top of the light sensor.
  4. Position a flashlight above cup C that shines light from the top into cup C directly onto the light sensor of your phone. You could, for example, attach the flashlight to a tripod or other kind of stand. If you have a very bright ceiling lamp, that might work as well. Your background light intensity reading on the app should ideally be above 1000 lux. Your setup should look similar to the one shown in Figure 2.
rb-reaction-setup
Figure 2. Before you mix solution A and B, place cup C on top of your phone's light sensor and set up a light source above cup C that provides enough light. Note: You will use a plastic cup instead of the beaker shown in this image. Also, you will put your phone in a plastic bag to protect it from any spills.
  1. Once you have positioned your light source and placed cup C on the phone's light sensor, you are ready to mix solution A and B. Open the Science Journal app and start a new experiment. Make sure to label it appropriately such as "4 scoops malonic acid," "3 scoops malonic acid," et cetera. Choose the light intensity sensor and switch to graph mode. Switch on your light source and check your light intensity readings. They should be constant as long as the light is not changing.
  2. Pour 10 mL of solution A into cup C using the beaker.
    1. Rinse the beaker out between uses with tap water.
  3. Before you mix in solution B, start a new trial for your first experiment in the app and press the record button.
  4. Then pour 10 mL of solution B into cup C and mix the combined solutions in cup C quickly with a spoon.
  5. Make sure cup C stays at the same location on top of the light sensor during mixing and throughout the whole reaction. Let the app record the color change over time. Observe on the graph how the light intensity changes with each color change. The reaction should turn blue/yellowish a number of times. The precise number of cycles depends on the starting conditions.
  6. Wait until the reaction stops cycling between colors. When the reaction stops, the solution will be a brown/purple color. At this point you can stop recording your data with the app.
  7. Carefully pour this solution down the sink with plenty of cold running water to wash it down. Be careful with this solution, as it contains iodine and will stain surfaces with which it comes in contact.
  8. Repeat the steps 6–11 two more times using solutions A and B. Remember, there will be some of solution A and solution B left over, since you made excess to ensure that you could do the procedure three times with equal amounts of liquid.
    1. You could repeat the procedure a fourth time with the remaining solutions, or dispose of them down a sink with cold running water.

Option 2: Using a stopwatch

  1. Label a third cup C. Be ready to observe and time the reaction process as soon as the two solutions are combined.
  2. Pour 10 mL of solution A into cup C using the beaker.
    1. Rinse the beaker out between uses with tap water.
  3. Pour 10 mL of solution B into cup C.
  4. Start the stopwatch immediately.
  5. Swirl the combined solutions in cup C to mix.
  6. Record the times at which the solution turns blue in your lab notebook.
    1. It should turn blue/yellowish a number of times. The precise number of cycles depends on the starting conditions.
    2. Have your helper write down the time the solution turned blue in the lab notebook while you watch the solution and the stopwatch. Or work out your own way to work together to record the times at which the solution turns blue.
    3. You could also use a video recorder to capture the changes in color if you choose. This will allow you determine more accurately the times at which color changes occurred.
  7. Wait until the reaction stops cycling between colors. When the reaction stops, the solution will be a brown/purple color.
  8. Carefully pour this solution down the sink with plenty of cold running water to wash it down. Be careful with this solution, as it contains iodine and will stain surfaces with which it comes in contact.
  9. Repeat the steps 1–8 two more times using solutions A and B. Remember, there will be some of solution A and solution B left over, since you made excess to ensure that you could do the procedure three times with equal amounts of liquid.
    1. You could repeat the procedure a fourth time with the remaining solutions, or dispose of them down a sink with cold running water.

Using Fewer Scoops of Malonic Acid in Solution B

In the following steps you will vary the amount of malonic acid that you add to solution B and test how the color changing behavior of the reaction is affected.

Making Solution A

  1. Clean the cup labeled A with tap water.
  2. Pour 40 ml of distilled water into cup A using the beaker.
  3. Add two scoops of sodium iodate and four level scoops of sulfamic acid.
  4. Swirl gently until the chemicals are dissolved.

Making Solution B

  1. Clean the cup labeled B with tap water.
  2. Add 40 mL of hydrogen peroxide to cup B using the beaker.
  3. Add three rounded scoops of malonic acid to cup B. Note this amount in your lab notebook.
  4. Add a small amount of manganese sulfate, about the size of a grain of rice.
  5. Shake the starch solution bottle, then add 10 drops of the starch solution to cup B.
  6. Swirl the solution to mix the chemicals.

Mixing the Solutions

  1. Mix solutions A and B in cup C.
  2. Clean the cup labeled C with tap water.
  3. Then, follow the same steps for mixing solution A and B as described above. Choose the same method for measuring the color change as before, recording your data either using the Science Journal app or the stopwatch.
  4. Repeat steps 1–3 two more times with the remaining solutions A and B.
  5. Carefully dispose of the solutions down a sink with cold running water.
  6. You should now continue to repeat Making Solution A through Mixing the Solutions of this section with the following amounts of malonic acid in step 3 of Making Solution B: two scoops, one scoop, then no scoops. You should end up with data for three trials for each of the different malonic acid amounts.

Analyze Your Results

  1. If you used the Science Journal app to record your data, look at the graph for one trial. It should look something like the graph in Figure 3. You can ignore the spiky part in the beginning that resulted from swirling the cup and mixing solution A and B. You can clearly see how the color change lead to an oscillating pattern of higher and lower light intensity. Where the light intensity is low, the color of the solution was darker (blue), whereas the light sensor could sense more light when the solution was clearer (yellow or colorless).
rb-screenshot
Figure 3. Example data from the Science Journal app. The x-axis of the graph shows time in minute:seconds [min:s] and the y-axis is light intensity in lux. The image shows how you can determine the oscillation period, or the time in between each color change, from your data.
  1. Drag the cursor along the graph to measure the time between each color change from yellow to blue, which is indicated by the lowest points in the graph. For example, in Figure 3, a color change happened at 31.3 seconds and 49.7 seconds. The difference between them is 18.4 seconds. Do this measurement for each peak in your graph. Note: It might be better to skip the last one or two peaks for your measurements as the oscillation decreases at the end of the reaction.
  2. From all your measurements, calculate the average time in between color change for this one trial. The result tells you the period of your oscillating reaction. A full oscillation period is completed once the reaction gets back to the color at which it started. If you invert the oscillation period (1/18.4) you will get the frequency of the oscillation.
  3. Repeat the measurements and calculations from step 1–3 for the other trials with the same amount of malonic acid.
  4. Average the times at which you observed the color change for trial 1, 2 and 3, and record the result in your lab notebook.
  5. Repeat steps 1–5 for the other amounts of malonic acid.
  6. Make a graph in which you show how the time in between color change depends on the amount of malonic acid added. Plot the average times at which the color changed to blue, or the oscillation period (in seconds), on the y-axis and the amount of malonic acid (number of scoops) on the x-axis.
  7. What happened as you decreased the amount of malonic acid in the reaction?
  8. From your graph recorded with the Science Journal app you can also derive how often the color changed back and forth for each reaction. You can determine the number of cycles by counting the number of peaks or valleys from the beginning to the end of the reaction. In Figure 3 this would be about seven or eight cycles. Again, count these for each individual trial and calculate the average for each amount of malonic acid.
  9. Make another graph that shows the number of color change cycles on the y-axis and the amount of scoops for malonic acid on the x-axis. Which amount of malonic acid resulted in the longest reaction with the most color changes?
  10. Discuss why the changes you observed occurred.

Communicating Your Results: Start Planning Your Display Board

Create an award-winning display board with tips and design ideas from the experts at ArtSkills.
ArtSkills button poster gallery 350
ArtSkills button design tips 350
ArtSkills button for more tips 210 h

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.


Variations

  • Vary other chemical components and discuss your observations about what happens in each case.
  • What happens if there is no starch?
  • The reaction generates gas. How would increasing the pressure above the reaction affect the reaction rate? Devise a way to test your prediction.
  • Vary the temperature; for example, 0, 10, 20, and 30°C.
  • Analyze the timing of the reaction using a digital recorder.
  • The oscillations of the Briggs-Rauscher reaction depend on the presence of free radicals in the solution. Adding antioxidants has been reported to change the oscillations due to their ability to "scavenge" the free radicals. Devise a way to use the Briggs-Rauscher reaction to test a chemical's ability to function as an antioxidant.
  • Try another Briggs-Rauscher reaction science project, Create Your Own Chemistry Color-analysis Tools, that involves simple, but cool, computer programming tools to capture the color changes.

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.

Ask an Expert

The Ask an Expert Forum is intended to be a place where students can go to find answers to science questions that they have been unable to find using other resources. If you have specific questions about your science fair project or science fair, our team of volunteer scientists can help. Our Experts won't do the work for you, but they will make suggestions, offer guidance, and help you troubleshoot.

Ask an Expert

Related Links

If you like this project, you might enjoy exploring these related careers:

Picture of chemist

Chemist

Everything in the environment, whether naturally occurring or of human design, is composed of chemicals. Chemists search for and use new knowledge about chemicals to develop new processes or products. Read more
chemistry teacher conducting classroom demonstration

Chemistry Teacher

When you hear the word chemicals, you might think of laboratories and scientists in white coats; but actually, chemicals are all around you, as well as inside of you. Everything in the world is made up of chemicals, also known as matter, or stuff that takes up space. Chemistry is the study of matter—what it is made of, how it behaves, its structure and properties, and how it changes during chemical reactions. Chemistry teachers are the people who help students understand this physical world, from the reactions within our own bodies to how soaps and detergents work and why egg proteins can keep a cookie from crumbling. They prepare the next generation of scientists and engineers, including all healthcare professionals. They also help also students develop scientific literacy. Read more
female chemical technician monitoring experiment

Chemical Technician

The role that the chemical technician plays is the backbone of every chemical, semiconductor, and pharmaceutical manufacturing operation. Chemical technicians conduct experiments, record data, and help to implement new processes and procedures in the laboratory. If you enjoy hands-on work, then you might be interested in the career of a chemical technician. Read more

News Feed on This Topic

 
, ,
Note: A computerized matching algorithm suggests the above articles. It's not as smart as you are, and it may occasionally give humorous, ridiculous, or even annoying results! Learn more about the News Feed

Looking for more science fun?

Try one of our science activities for quick, anytime science explorations. The perfect thing to liven up a rainy day, school vacation, or moment of boredom.

Find an Activity