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Science project, catalase and hydrogen peroxide experiment.

How do living cells interact with the environment around them? All living things possess catalysts , or substances within them that speed up chemical reactions and processes. Enzymes are molecules that enable the chemical reactions that occur in all living things on earth. In this catalase and hydrogen peroxide experiment, we will discover how enzymes act as catalysts by causing chemical reactions to occur more quickly within living things. Using a potato and hydrogen peroxide, we can observe how enzymes like catalase work to perform decomposition , or the breaking down, of other substances. Catalase works to speed up the decomposition of hydrogen peroxide into oxygen and water. We will also test how this process is affected by changes in the temperature of the potato. Is the process faster or slower when compared to the control experiment conducted at room temperature?

What happens when a potato is combined with hydrogen peroxide?

• Hydrogen peroxide
• Small glass beaker or cup
• Divide the potato into three roughly equal sections.
• Keep one section raw and at room temperature.
• Place another section in the freezer for at least 30 minutes.
• Boil the last section for at least 5 minutes.
• Chop and mash a small sample (about a tablespoon) of the room temperature potato and place into beaker or cup.
• Pour enough hydrogen peroxide into the cup so that potato is submerged and observe.
• Repeat steps 5 & 6 with the boiled and frozen potato sections.

Observations & Results

Watch each of the potato/hydrogen peroxide mixtures and record what happens. The bubbling reaction you see is the metabolic process of decomposition , described earlier. This reaction is caused by catalase, an enzyme within the potato. You are observing catalase breaking hydrogen peroxide into oxygen and water. Which potato sample decomposed the most hydrogen peroxide? Which one reacted the least?

You should have noticed that the boiled potato produced little to no bubbles. This is because the heat degraded the catalase enzyme, making it incapable of processing the hydrogen peroxide. The frozen potato should have produced fewer bubbles than the room temperature sample because the cold temperature slowed the catalase enzyme’s ability to decompose the hydrogen peroxide. The room temperature potato produced the most bubbles because catalase works best at a room temperature.

Conclusions

Catalase acts as the catalyzing enzyme in the decomposition of hydrogen peroxide. Nearly all living things possess catalase, including us! This enzyme, like many others, aids in the decomposition of one substance into another. Catalase decomposes, or breaks down, hydrogen peroxide into water and oxygen.

Want to take a closer look? Go further in this experiment by looking at a very small sample of potato combined with hydrogen peroxide under a microscope!

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Hydrogen peroxide decomposition using different catalysts

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From fresh liver, to powdered manganese, create different catalysts to explore the effervescent world of hydrogen peroxide decomposition 

Your shopping list might look strange, but this practical will be well worth it. Supporting student to understand reaction rates, catalysis, and enzymes.

This experiment should take 5 minutes.

Equipment 

• Eye protection
• Measuring cylinders, 250 cm 3 , x1 for each catalyst
• Large tray for spills
• Hydrogen peroxide solution, 75 cm 3 ,100 vol
• Powdered manganese(IV) oxide (manganese dioxide, MnO 2 ), 0.5 g
• Lead(IV) oxide (lead dioxide, PbO 2 ), 0.5 g
• iron(III) oxide (red iron oxide, Fe 2 O 3 ), 0.5 g
• Potato, 1 cm 3
• Liver, 1 cm 3

Health, safety and technical notes

• Read our standard health and safety guidance .
• Always wear eye protection.
• Hydrogen peroxide is corrosive, see CLEAPSS Hazcard HC050 .
• Manganese oxide is harmful if swallowed or inhaled, see CLEAPSS Hazcard HC060 .
• Lead dioxide is a reproductive toxin, harmful if swallowed or inhaled, a Specific Target Organ Toxin and hazardous to the aquatic environment, see CLEAPSS Hazcard HC056 .
• Avoid contact of the catalysts with aluminium and other metal powders, explosive reactions can occur.

Before the demonstration

• Line up five 250 cm 3 measuring cylinders in a tray.
• Add 75 cm 3 of water to the 75 cm 3 of 100 volume hydrogen peroxide solution to make 150 cm 3 of 50 volume solution.

The demonstration

• Place about 1 cm 3 of washing up liquid into each of the measuring cylinders.
• To each one add the amount of catalyst specified above.
• Then add 25 cm 3 of 50 volume hydrogen peroxide solution to each cylinder. The addition of the catalyst to each cylinder should be done as nearly simultaneously as possible – using two assistants will help.
• Start timing.
• Foam will rise up the cylinders.
• Time how long each foam takes to rise to the top (or other marked point) of the cylinder.
• The foam from the first three cylinders will probably overflow considerably.
• Place a glowing spill in the foam; it will re-light, confirming that the gas produced is oxygen.

The lead dioxide will probably be fastest, followed by manganese dioxide and liver. Potato will be much slower and the iron oxide will barely produce any foam. This order could be affected by the surface areas of the powders.

Some students may believe that the catalysts – especially the oxides – are reactants because hydrogen peroxide is not noticeably decomposing at room temperature.

The teacher could point out the venting cap on the peroxide bottle as an indication of continuous slow decomposition.

Alternatively, s/he could heat a little hydrogen peroxide in a conical flask with a bung and delivery tube, collect the gas over water in a test-tube and test it with a glowing spill to confirm that it is oxygen.

This shows that no other reactant is needed to decompose hydrogen peroxide.

NB: Simply heating 50 volume hydrogen peroxide in a test-tube will not succeed in demonstrating that oxygen is produced. The steam produced will tend to put out a glowing spill. Collecting the gas over water has the effect of condensing the steam. It is also possible to ‘cheat’ by dusting a beaker with a tiny, almost imperceptible, amount of manganese dioxide prior to the demonstration and pouring hydrogen peroxide into it. Bubbles of oxygen will be formed in the beaker.

The reaction is :

2H 2 O 2 (aq) → 2H 2 O(l) + O 2 (g)

This is catalysed by a variety of transition metal compounds and also by peroxidase enzymes found in many living things.

• Repeat the experiment, but heat the liver and the potato pieces for about five minutes in boiling water before use.
• There will be almost no catalytic effect, confirming that the catalyst in these cases is an enzyme that is denatured by heat.
• Investigate the effect of using lumpy or powdered manganese dioxide.
• The powdered oxide will be more effective because of its greater surface area.
• Try using other metal oxides or iron filings as catalysts.
• Animal blood may be used instead of liver if local regulations allow this.
• One teacher suggested measuring the height of the foam over suitable time intervals and plotting a graph.

More resources

Add context and inspire your learners with our short career videos showing how chemistry is making a difference .

Hydrogen peroxide decomposition using different catalysts - teacher notes

Additional information.

This practical is part of our Classic Chemistry Demonstrations  collection.

• 14-16 years
• 16-18 years
• Demonstrations
• Reactions and synthesis
• Rates of reaction

Specification

• Catalysts are substances that speed up chemical reactions but can be recovered chemically unchanged at the end of the reaction.
• (d) catalysts as substances that increase the rate of a reaction while remaining chemically unchanged and that they work by lowering the energy required for a collision to be successful (details of energy profiles are not required)
• (e) characteristics of a catalyst
• 2.3.2 suggest appropriate practical methods to measure the rate of a reaction and collect reliable data (methods limited to measuring a change in mass, gas volume or formation of a precipitate against time) for the reaction of: metals with dilute acid;…
• 2.3.2 suggest appropriate practical methods to measure the rate of a reaction and collect reliable data (methods limited to measuring a change in mass, gas volume or formation of a precipitate against time) for the reaction of: metals with dilute acid…
• Rate of reaction.
• (ii) catalysts.
• Enzymes as catalysts produced by living cells (two examples).
• WS.3.5 Interpreting observations and other data (presented in verbal, diagrammatic, graphical, symbolic or numerical form), including identifying patterns and trends, making inferences and drawing conclusions.
• Catalysts change the rate of chemical reactions but are not used up during the reaction. Different reactions need different catalysts.
• Enzymes act as catalysts in biological systems.
• Factors which affect the rates of chemical reactions include: the concentrations of reactants in solution, the pressure of reacting gases, the surface area of solid reactants, the temperature and the presence of catalysts.
• WS3.5 Interpreting observations and other data (presented in verbal, diagrammatic, graphical, symbolic or numerical form), including identifying patterns and trends, making inferences and drawing conclusions.
• Recall that enzymes act as catalysts in biological systems.
• Describe the characteristics of catalysts and their effect on rates of reaction.
• 3e Interpreting observations and other data (presented in verbal, diagrammatic, graphical, symbolic or numerical form), including identifying patterns and trends, making inferences and drawing conclusions
• 7.6 Describe a catalyst as a substance that speeds up the rate of a reaction without altering the products of the reaction, being itself unchanged chemically and in mass at the end of the reaction
• 7.8 Recall that enzymes are biological catalysts and that enzymes are used in the production of alcoholic drinks
• IaS2.11 in a given context interpret observations and other data (presented in diagrammatic, graphical, symbolic or numerical form) to make inferences and to draw reasoned conclusions, using appropriate scientific vocabulary and terminology to communicat…
• C6.2.4 describe the characteristics of catalysts and their effect on rates of reaction
• C6.2.5 identify catalysts in reactions
• C6.2.14 describe the use of enzymes as catalysts in biological systems and some industrial processes
• C6.2.13 describe the use of enzymes as catalysts in biological systems and some industrial processes
• WS.1.3e interpreting observations and other data
• C5.1f describe the characteristics of catalysts and their effect on rates of reaction
• C5.1i recall that enzymes act as catalysts in biological systems
• C5.2f describe the characteristics of catalysts and their effect on rates of reaction
• C5.2i recall that enzymes act as catalysts in biological systems

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Biology Teaching Resources

Catalase Activity in Yeast Using Sodium Alginate

Have you ever noticed that when you put hydrogen peroxide on a wound, it bubbles? The bubbles form from an reaction where hydrogen peroxide is broken down into water and oxygen. This reaction is a fantastic way to observe enzymes and substrates in action.

I have several activities exploring this reaction. In one, students simply observe bubbles when hydrogen peroxide comes into contact with different tissues. This enzyme investigation requires minimal set-up and is appropriate even for beginning students.

For my AP Biology students, I have used a floating disk method to obtain quantitative data. Though, this method can be problematic. Sometimes the disks don’t float. Sometimes they float so quickly that it can be difficult to accurately measure time.

In this version of the lab, students use sodium alginate to create spheres of yeast. The procedure is fairly simple and students can make the spheres and store them for several days. Then, they drop the spheres into hydrogen peroxide and measure how quickly they float to the surface. The time it takes to reach the surface is an indirect measure of the speed of the reaction. Students observe the spheres in different concentrations of hydrogen peroxide (3%, 1.5%, and .75%).

Once students have the procedure mastered, they explore how temperate affects the rate of reaction. Students design the experiment, gather data, and write a lab report explaining the results. Students can even do this lab before they have a complete understanding of enzymes and substrates. The introduction gives them enough background information to explore the phenomenon.

This is the set-up preparation for my class. I put the yeast and sodium alginate in medicine cups (10 ml of each). Then students make the spheres using the large pipettes. Students make the spheres and we store them for data collection the following day.

Shannan Muskopf

Practical Biology

A collection of experiments that demonstrate biological concepts and processes.

Observing earthworm locomotion

Practical Work for Learning

Published experiments

Investigating an enzyme-controlled reaction: catalase and hydrogen peroxide concentration, class practical or demonstration.

Hydrogen peroxide ( H 2 O 2 ) is a by-product of respiration and is made in all living cells. Hydrogen peroxide is harmful and must be removed as soon as it is produced in the cell. Cells make the enzyme catalase to remove hydrogen peroxide.

This investigation looks at the rate of oxygen production by the catalase in pureed potato as the concentration of hydrogen peroxide varies. The oxygen produced in 30 seconds is collected over water. Then the rate of reaction is calculated.

Lesson organisation

You could run this investigation as a demonstration at two different concentrations, or with groups of students each working with a different concentration of hydrogen peroxide. Individual students may then have time to gather repeat data. Groups of three could work to collect results for 5 different concentrations and rotate the roles of apparatus manipulator, result reader and scribe. Collating and comparing class results allows students to look for anomalous and inconsistent data.

Apparatus and Chemicals

For each group of students:.

Pneumatic trough/ plastic bowl/ access to suitable sink of water

Conical flask, 100 cm 3 , 2

Syringe (2 cm 3 ) to fit the second hole of the rubber bung, 1

Measuring cylinder, 100 cm 3 , 1

Measuring cylinder, 50 cm 3 , 1

Clamp stand, boss and clamp, 2

Stopclock/ stopwatch

For the class – set up by technician/ teacher:

Hydrogen peroxide, range of concentrations, 10 vol, 15 vol, 20 vol, 25 vol, and 30 vol, 2 cm 3 per group of each concentration ( Note 1 )

Pureed potato, fresh, in beaker with syringe to measure at least 20 cm 3 , 20 cm 3 per group per concentration of peroxide investigated ( Note 2 )

Rubber bung, 2-holed, to fit 100 cm 3 conical flasks – delivery tube in one hole (connected to 50 cm rubber tubing)

Health & Safety and Technical notes

Wear eye protection and cover clothing when handling hydrogen peroxide. Wash splashes of pureed potato or peroxide off the skin immediately. Be aware of pressure building up if reaction vessels become blocked. Take care inserting the bung in the conical flask – it needs to be a tight fit, so push and twist the bung in with care.

Read our standard health & safety guidance

1 Hydrogen peroxide: (See CLEAPSS Hazcard) Solutions less than 18 vol are LOW HAZARD. Solutions at concentrations of 18-28 vol are IRRITANT. Take care when removing the cap of the reagent bottle, as gas pressure may have built up inside. Dilute immediately before use and put in a clean brown bottle, because dilution also dilutes the decomposition inhibitor. Keep in brown bottles because hydrogen peroxide degrades faster in the light. Discard all unused solution. Do not return solution to stock bottles, because contaminants may cause decomposition and the stock bottle may explode after a time.

2 Pureed potato may irritate some people’s skin. Make fresh for each lesson, because catalase activity reduces noticeably over 2/3 hours. You might need to add water to make it less viscous and easier to use. Discs of potato react too slowly.

3 If the bubbles from the rubber tubing are too big, insert a glass pipette or glass tubing into the end of the rubber tube.

SAFETY: Wear eye protection and protect clothing from hydrogen peroxide. Rinse splashes of peroxide and pureed potato off the skin as quickly as possible.

Preparation

a Make just enough diluted hydrogen peroxide just before the lesson. Set out in brown bottles ( Note 1 ).

b Make pureed potato fresh for each lesson ( Note 2 ).

c Make up 2-holed bungs as described in apparatus list and in diagram.

Investigation

d Use the large syringe to measure 20 cm 3 pureed potato into the conical flask.

e Put the bung securely in the flask – twist and push carefully.

f Half-fill the trough, bowl or sink with water.

g Fill the 50 cm 3 measuring cylinder with water. Invert it over the trough of water, with the open end under the surface of the water in the bowl, and with the end of the rubber tubing in the measuring cylinder. Clamp in place.

h Measure 2 cm 3 of hydrogen peroxide into the 2 cm 3 syringe. Put the syringe in place in the bung of the flask, but do not push the plunger straight away.

i Check the rubber tube is safely in the measuring cylinder. Push the plunger on the syringe and immediately start the stopclock.

j After 30 seconds, note the volume of oxygen in the measuring cylinder in a suitable table of results. ( Note 3 .)

k Empty and rinse the conical flask. Measure another 20 cm 3 pureed potato into it. Reassemble the apparatus, refill the measuring cylinder, and repeat from g to j with another concentration of hydrogen peroxide. Use a 100 cm 3 measuring cylinder for concentrations of hydrogen peroxide over 20 vol.

l Calculate the rate of oxygen production in cm 3 /s.

m Plot a graph of rate of oxygen production against concentration of hydrogen peroxide.

Teaching notes

Note the units for measuring the concentration of hydrogen peroxide – these are not SI units. 10 vol hydrogen peroxide will produce 10 cm 3 of oxygen from every cm 3 that decomposes.( Note 1 .)

In this procedure, 2 cm 3 of 10 vol hydrogen peroxide will release 20 cm 3 of oxygen if the reaction goes to completion. 2 cm 3 of liquid are added to the flask each time. So if the apparatus is free of leaks, 22 cm 3 of water should be displaced in the measuring cylinder with 10 vol hydrogen peroxide. Oxygen is soluble in water, but dissolves only slowly in water at normal room temperatures.

Use this information as a check on the practical set-up. Values below 22 cm 3 show that oxygen has escaped, or the hydrogen peroxide has not fully reacted, or the hydrogen peroxide concentration is not as expected. Ask students to explain how values over 22 cm 3 could happen.

An error of ± 0.05 cm 3 in measuring out 30 vol hydrogen peroxide could make an error of ± 1.5 cm 3 in oxygen production.

Liver also contains catalase, but handling offal is more controversial with students and introduces a greater hygiene risk. Also, the reaction is so vigorous that bubbles of mixture can carry pieces of liver into the delivery tube.

If collecting the gas over water is complicated, and you have access to a 100 cm 3 gas syringe, you could collect the gas in that instead. Be sure to clamp the gas syringe securely but carefully.

The reaction is exothermic. Students may notice the heat if they put their hands on the conical flask. How will this affect the results?

Health and safety checked, September 2008

http://www.saps.org.uk/secondary/teaching-resources/293-student-sheet-24-microscale-investigations-with-catalase Microscale investigations with catalase – which has been transcribed onto this site at Investigating catalase activity in different plant tissues.

(Website accessed October 2011)

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Valentine’s Day Elephant Toothpaste

Science can be super cool to try and super easy to set up at the same time. Let’s show kids how fun science can be! This Valentine’s Day hydrogen peroxide and yeast experiment  is a must try experiment for a real WOW! We have loads of simple Valentine’s Day science experiments you can easily do at home or in the classroom.

Explore Chemical Reactions For Valentine’s Day

We, of course, love the holidays here, so it’s fun to give a classic chemistry experiments a Valentine’s Day theme!

Pink and red and hearts are added to most of our Valentine’s Day science activities and this Valentine’s Day hydrogen peroxide and yeast experiment has plenty of pink and red! Food coloring is a super simple way to give science a holiday theme. My son is also very generous with his food coloring use.

The reaction between the hydrogen peroxide and the yeast makes for an awesome foam that is perfectly safe for little hands to play with and a breeze to clean up. However, this science experiment is not edible! We love fun chemical reaction experiments!

Check out the awesome photos below and at the end, you will see everything you need to set up your own hydrogen peroxide and yeast experiment or Elephant Toothpaste for Valentine’s Day.

What Is Chemistry?

Let’s keep it basic for our younger or junior scientists! Chemistry is all about the way different materials are put together, and how they are made up including atoms and molecules. It’s also how these materials act under different conditions. Chemistry is often a base for physics so you will see overlap!

What might you experiment with in chemistry? Classically we think of a mad scientist and lots of bubbling beakers, and yes there is a reaction between bases and acids to enjoy! Also, chemistry involves matter, changes, solutions, and the list goes on and on.

We will be exploring simple chemistry you can do at home or in the classroom that isn’t too crazy, but is still lots of fun for kids! You can check out some more chemistry activities here . Check out the video! You can never recreate the same look twice.

Helpful Science Resources To Get You Started

Here are a few resources that will help you introduce science more effectively to your kiddos or students and feel confident yourself when presenting materials. You’ll find helpful free printables throughout.

• Best Science Practices (as it relates to the scientific method)
• Science Vocabulary
• 8 Science Books for Kids
• All About Scientists
• Free Science Worksheets
• Science Supplies List
• Science Tools for Kids
• Join us in the Club

Free Printable Valentine STEM Activities Calendar

Why Is It Called Elephant’s Toothpaste?

This classic chemistry experiment is often called Elephant’s toothpaste because of the voluminous amount of foam that it produces. However, you do need a much stronger percentage of hydrogen peroxide to produce that reaction than what we use below.

Check out our elephant toothpaste experiment with stronger peroxide!

You can still enjoy the same type of chemistry experiment but with less foam and less of an exothermic reaction with regular household hydrogen peroxide. The experiment is still awesome, and if you get a chance to try a higher percentage of peroxide, it will be worth it too!

Why Does Hydrogen Peroxide Foam?

The reaction between hydrogen peroxide and yeast is called an exothermic reaction. You will feel a warmth to the outside of the container because energy is being released in the form of heat.

The yeast helps to remove the oxygen from the hydrogen peroxide creating tons of tiny bubbles that made all that cool foam. The foam is the oxygen, water, and dish soap that you added.

Hydrogen peroxide is a relatively unstable compound, and it naturally breaks down into water and oxygen over time. However, this process is slow. In the experiment, yeast acts as a catalyst, speeding up that reaction.

Yeast contains catalase, an enzyme that helps breakdown hydrogen peroxide into water and oxygen. The yeast increases the rate at which hydrogen peroxide decomposes.

As the hydrogen peroxide decomposes, it produces oxygen gas. The oxygen gas forms bubbles, and these bubbles create foam as they rise to the surface of the liquid. The foam or bubbling you can see, is evidence of the release of oxygen.

If you pay close attention, the reaction continues for quite a while and looks quite different depending on the size of the container you use! We chose three different size flasks to check out this Valentines Day hydrogen peroxide and yeast exothermic reaction. Each one looked pretty cool.

Valentine’s Day Hydrogen Peroxide and Yeast Experiment

• Hydrogen Peroxide
• Yeast Packets {we used two packets for the three beakers}
• Flasks or Plastic Bottles
• Teaspoon and Tablespoon
• Food Coloring
• Tray or Container {to place bottles or beakers on to catch foam}
• Small Cup {mixing yeast and water}

STEP 1: Pour the same amount of hydrogen peroxide into each container unless you are just using one container. We used a 1/2 cup.

STEP 2. Then squirt dish soap into flask or bottle and swish it around a bit to mix!

STEP 3. Next add food coloring (as much as you like, my son is very generous).

STEP 4: Make the yeast mixture by mixing 1 tablespoon of yeast with 3 tablespoons of very warm water. Stir to dissolve the yeast as best as possible. It may appear clumpy still but that’s fine!

STEP 5: Pour the yeast mixture into the container and check out what happens! You can even add a few more drops of food coloring as the mixture swells out of the container.

Notice how quickly the reaction begins. The foam had started before he was even finished pouring in the rest of the mixture.

For the larger flask, the reaction continued for quite a while inside the container before it came out of the top. Would a different amount of hydrogen and yeast change that?

BELOW IS THE MEDIUM SIZED FLASK SHOWING THE CHEMICAL REACTION FROM START TO FINISH

Check out all that cool foam being produced by the reaction between the hydrogen peroxide and the yeast!

Go ahead and play around with the foam. My son added additional red food coloring. This will temporarily stain the hands if you use as much as my son! If we stayed with the pink foam this would not have happened.

You can also go ahead and whip up new yeast mixtures and add it with extra hydrogen peroxide to the already foamy bottles or flasks. We always do this with our baking soda and vinegar reactions !

More Fun Valentine’s Day Science Experiments

You can find all our Valentine’s Day science experiments here , including…

• Fizzing Hearts
• Heart Lava Lamp
• Valentines Skittles Experiment
• Dissolving Candy Heart Science
• Grow Salt Crystal Hearts
• Water Displacement Experiment

Printable Valentine STEM Project Pack

Countdown to Valentine’s Day with science and STEM ! Pack includes complete instructions, templates, and images for 20+ activities. Bonus: printable science Valentine’s Day cards!

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Elephant Toothpaste – Two Ways to Make It

Elephant toothpaste is a chemical reaction that makes a volcano of foam when soapy water traps gases from the rapid decomposition of hydrogen peroxide. There are two easy methods for making elephant toothpaste. One makes a giant mountain of foam, while the other produces a smaller effect but is safe enough for kids to touch. The dramatic reaction uses strong peroxide and potassium iodide, while the kid-friendly version uses dilute peroxide and replaces potassium iodide with yeast. Here are instructions for both methods and a look at the chemistry involved.

Why Is It Called Elephant Toothpaste?

First, you may wonder why the reaction has the name “elephant toothpaste.” It’s because the thick column of foam escaping a tube looks like toothpaste big enough for an elephant to use. Also, it’s a lot easier and more descriptive than calling the reaction “rapid decomposition of peroxide”. After all, the point of elephant toothpaste is engaging people in the wonder of science. Even if someone doesn’t understand the chemistry, the project is fun and entertaining.

How to Make Giant Elephant Toothpaste

When you see videos of the world’s largest elephant toothpaste, you’re viewing the classic version of the demonstration.

This version uses concentrated hydrogen peroxide, potassium iodide or sodium iodide, liquid dishwashing detergent, water, and (if desired) food coloring:

• 30% hydrogen peroxide (H 2 O 2 )
• Potassium iodide (KI) or sodium iodide (NaI)
• Liquid dishwashing detergent
• Food coloring (optional)
• Large graduated cylinder or Erlenmeyer flask
• Tray or tarp to catch the foam

The chemicals are available online, although it’s easier to just pick up the peroxide at a beauty supply store. Choose any tall container for the demonstration, but use glass and not plastic because the reaction generates heat.

Start by putting on proper safety gear, including safety goggles and gloves.

• First, prepare a saturated solution of potassium iodide or sodium iodide in water. In a beaker, dissolve crystals of either chemical in about 120 ml (4 ounces) of water. Continue stirring in the solid until no more dissolves. It takes about a tablespoon of the dry chemical. But, measurements are not critical here. Set aside the solution for now.
• Set the cylinder or flask in a tray or on a tarp. Pour about 60 ml (2 ounces) of 30% hydrogen peroxide into the glass tube. Add a squirt (about 5 ml) of dishwashing liquid to the tube. If you want colored foam, add a few drops of food coloring. Swirl the liquids to mix them. Here again, exact measurements are unnecessary.
• When you’re ready for the reaction, pour about 15 ml (one tablespoon) of the iodide solution and stand back. Foam forms within seconds and rapidly escapes the tube.
• After the reaction ends, wash the contents of the tray and tube down the drain with water.

Kid-Friendly Elephant Toothpaste

The classic chemistry demonstration is for chemistry educators, but the kid-friendly elephant toothpaste is safe enough for parents and children to perform and touch. Also, this version uses easy-to-find ingredients.

• 3% household peroxide
• 1-2 packet of dry yeast
• Food coloring
• Empty plastic soft drink bottle
• Cookie sheet or pan to catch the foam (optional)

It’s not necessary to don safety gear for this reaction and it’s fine to use either a plastic or glass container. Just make sure the bottle has a narrow opening because this channels the foam and improves the effect.

Don’t worry about measuring ingredients precisely.

• Pour about a cup of 3% hydrogen peroxide into an empty bottle. If the bottle opening is small, use a funnel.
• Add a couple of squirts of dishwashing liquid and a few drops of food coloring to the bottle. Swish the liquid around to mix it.
• In a separate container, mix together yeast with enough warm water that the liquid is easy to pour. A paper cup is a great container choice because you can pinch its rim and make pouring the yeast mixture easier. Wait a couple of minutes before proceeding so the yeast has a chance to activate.
• When you’re ready, place the bottle on a cookie sheet or pan and pour yeast mixture into the bottle
• Clean-up using warm, soapy water.

Is Elephant Toothpaste Safe to Touch?

You can handle the ingredients and the foam from the kid-friendly elephant toothpaste project. However, don’t touch either the ingredients or the foam from the classic giant elephant toothpaste. This is because the peroxide is concentrated enough to cause a chemical burn, while the giant toothpaste is hot enough to cause a thermal burn.

How Elephant Toothpaste Works

The basis for the elephant toothpaste display is the rapid decomposition of hydrogen peroxide (H 2 O 2 ). Hydrogen peroxide naturally decomposes into water and oxygen gas according to this chemical reaction:

2H 2 O 2 (l) → 2H 2 O(l) + O 2 (g)

In a decomposition reaction , a larger molecule breaks down into two or more smaller molecules. The normally slow progression of the reaction is why a bottle of peroxide has a shelf life . Exposure to light accelerates the decomposition, which is why peroxide comes in opaque containers.

Either potassium iodide or the enzyme catalase (found in yeast) acts as a catalyst for the reaction. In other words, either of these chemicals supercharges the reaction so it proceeds very quickly. Breaking chemical bonds in peroxide releases a lot of energy. Only a fraction of this energy goes back into forming chemical bonds making water and oxygen. What this means is that elephant toothpaste is an exothermic reaction or one that releases heat. How hot the reaction gets depends on how much peroxide you start with and how efficiently the catalyst speeds up the reaction. So, the classic version of the project gets hot enough to steam. The kid-friendly version of elephant toothpaste gets warm, but not hot enough to cause a burn.

Producing gas isn’t enough to make a foamy volcano. Adding liquid soap or dishwashing detergent to the mixture traps the gas bubbles. Normally, the reaction doesn’t have much color. Using food coloring makes the foam more interesting. Depending on your choice of colors, it also makes the foam resemble toothpaste.

• Dirren, Glen; Gilbert, George; Juergens, Frederick; Page, Philip; Ramette, Richard; Schreiner, Rodney; Scott, Earle; Testen, May; Williams, Lloyd. (1983).  Chemical Demonstrations: A Handbook for Teachers of Chemistry. Vol. 1.  University of Wisconsin Press. Madison, Wisconsin. doi:10.1021/ed062pA31.2
• “ Elephant’s Toothpaste .”  University of Utah Chemistry Demonstrations . University of Utah.
• Hernando, Franco; Laperuta, Santiago; Kuijl, Jeanine Van; Laurin, Nihuel; Sacks, Federico; Ciolino, Andrés (2017). “Elephant Toothpaste”.  Journal of Chemical Education . 94 (7): 907–910. doi: 10.1021/acs.jchemed.7b00040
• IUPAC (1997). “Chemical decomposition”. Compendium of Chemical Terminology (the “Gold Book”) (2nd ed.). Oxford: Blackwell Scientific Publications. ISBN 0-9678550-9-8. doi: 10.1351/goldbook

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Experimenting: Yeast, Hydrogen Peroxide Chemical Reaction (fire)

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Hydrogen Peroxide Experiments

The Effects of pH on Catechol Oxidase

Chemically, hydrogen peroxide has a similar composition to water, except its molecule has an additional oxygen atom. Simple experiments, some of which you can do at home, involve breaking down hydrogen peroxide into water and oxygen, using catalysts to quicken the reaction. Other experiments show the presence of oxygen. Hydrogen peroxide, in combination with other products, can produce visible chemical reactions.

TL;DR (Too Long; Didn't Read)

You can do simple experiments with drugstore hydrogen peroxide at home, breaking it down into water and oxygen.

Hydrogen Peroxide and Yeast

Hydrogen peroxide is relatively unstable, so over time it breaks down into water and oxygen. In this experiment, yeast is added to hydrogen peroxide to speed up its decomposition process, which is normally slow. You can perform the experiment at home in a sink. You'll need an empty large soda bottle, 3 percent hydrogen peroxide from a grocery store, one packet of active yeast, liquid dish soap and warm water. Mix about 113 grams (4 ounces) of the hydrogen peroxide with 56 grams (2 ounces) of dish soap in the soda bottle. Set aside and mix the packet of yeast with warm water, letting it sit for about five minutes. Pour the yeast mixture into the soda bottle. The reaction produces oxygen gas and the addition of liquid detergent creates foam.

Hydrogen Peroxide and Bleach

The mixture of hydrogen peroxide and bleach creates oxygen gas, salt (sodium chloride) and water. The bleach must contain sodium hypochlorite for this experiment to work. The solutions do not need to be concentrated to get a quick reaction. You will need 3 percent hydrogen peroxide, approximately 6 percent household bleach and a beaker. Pour 56 grams (2 ounces) of bleach into the beaker and the equivalent of hydrogen peroxide. Once the two are mixed, the reaction will occur quickly, producing bubbling.

Hydrogen Peroxide and Burning Sulfur

This experiment doesn't decompose hydrogen peroxide but merely shows that it contains oxygen. You expose a rose to burning sulfur and then dip it in hydrogen peroxide. You'll need two drinking cups, a rose with a small stem, tape, foil, sulfur and hydrogen peroxide. Tape the rose to the inside of the first cup and place a small pile of sulfur on a piece of aluminum foil. Add flame to the sulfur until it starts to smolder -- turn the cup with the rose upside down over the burning sulfur. The rose is exposed to sulfur dioxide gas, turning the petals of the rose to white as the gas combines with the oxygen in the colored part of the rose. Remove the rose from the cup and dip it into a cup filled halfway with hydrogen peroxide. The hydrogen peroxide provides oxygen to the flower, restoring its color.

Safety Considerations

Make sure to wear protective eyewear when conducting any of these experiments, whether at home or in a classroom or lab setting. If hydrogen peroxide comes in contact with your eyes, it can result in damage or blindness. It is imperative to seek medical attention if this happens. Make sure to wear an apron and clothing that covers your skin. According to the Agency for Toxic Substances and Disease Registry website, hydrogen peroxide can cause skin irritation -- there may also be skin burns with blisters with exposure to concentrated solutions. The peroxide you buy in the drug store is typically 3 percent, whereas chemists and other professionals might use stronger concentrations of 35 to 50 percent. Flush your skin with water if it is exposed to hydrogen peroxide.

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• Agency for Toxic Substances and Disease Registry: ToxFAQs for Hydrogen Peroxide
• Lansing Community College: The reaction of bleach and hydrogen peroxide

About the Author

Based in New Hamburg, Ontario, Mary Margaret Peralta has been writing for websites since 2010. She has developed a company website and a health and safety manual for a past employer. Peralta obtained her Bachelor of Arts in sociology from the University of Waterloo in Waterloo, Ontario.

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Exploring Catalase and Invertase Activity Using Sodium Alginate-Encapsulated Yeast (Yeast Spheres) †

Associated data.

Appendix 2: Preparation background and supplies

Appendix 3. Sample instructions for testing catalase activity

INTRODUCTION

Finding the right enzyme experiment can be problematic, depending what one is trying to show, what supplies and equipment are available, and the time one can devote to the topic. Experiments range from those that only indicate presence/absence of enzyme activity ( 4 ) to those that require time-consuming isolation procedures and spectrophotometric analysis ( 1 , 2 , 6 ). I have developed simple and inexpensive procedures for looking at catalase and invertase activity using yeast encapsulated in sodium alginate, a technique that has been used for several applications, including the production of alcoholic beverages ( 3 ) and for investigating fermentation in teaching labs ( 5 ).

Catalase activity using yeast spheres may be explored with or without gas pressure sensors. Without sensors available, an easy and very reliable method is to use graduated cylinders filled with H 2 O 2 . A yeast sphere is dropped into a graduated cylinder containing H 2 O 2 , the substrate. The sphere will sink to the bottom of the cylinder and then, as the catalase produced by the yeast reacts with the hydrogen peroxide to form O 2 gas bubbles around the sphere, the sphere will rise to the surface. Because the reaction is quick, multiple replicates may be performed in a very short period of time, and thus statistics can easily be incorporated into the data analysis. With sensors, a few grams of yeast spheres are added to an Erlenmeyer flask containing H 2 O 2 , the sensor is attached, and pressure readings are recorded. Experiments may be designed to test the effect of substrate (H 2 O 2 ) concentration, temperature, or pH on the catalase reaction. The trends in activity are similar no matter which method is used ( Appendix 1 ).

Invertase catalyzes the hydrolysis of sucrose to glucose and fructose; thus the activity of invertase may be measured by the appearance of glucose. With yeast cells encapsulated in sodium alginate, there are no cells in solution to interfere with the various ways to test for glucose. One of the easiest ways to test for glucose is to use urine analysis test strips. The strips are dipped into the solution surrounding the spheres and the color change is compared to a color chart: the more glucose in solution the darker the color. If a more quantitative method is desired, samples from the solution surrounding the yeast spheres may be withdrawn and tested for the presence of glucose using glucose oxidase. Experiments may be designed to test the effect of temperature or substrate (sucrose) concentration on the invertase reaction. The results mirror each other no matter what method is used ( Appendix 1 ).

Preparation of yeast spheres

A day or two before the lab period, make a 2% sodium alginate solution in beakers or plastic cups, and leave it out at room temperature. The sodium alginate solution is viscous and takes a while to get into solution which is why I recommend making a separate beaker/cup for each lab group instead of making a big batch and trying to aliquot it out when ready to use ( Appendix 2 ).

On the day of the experiment, about 10 minutes before students will be making their yeast spheres, make a 10% solution of yeast in warm tap water (I use Fleischman’s RapidRise bread yeast, Saccharomyces cerevisiae ). Have students add an equal volume of the yeast suspension to their cup of 2% sodium alginate. This solution should be mixed well and then drawn up into a syringe. A plastic pipet may also be used, but syringes give a little more control and consistency in size and also allow more yeast spheres to be made at once.

All excess liquid should be wiped off the syringe, and the syringe then held over a cup or beaker containing 0.15M CaCl 2 . As the syringe plunger is very slowly depressed, uniform drops of the yeast-sodium alginate solution will form spheres as they come in contact with the CaCl 2 solution and these will fall to the bottom of the beaker. After all of the yeast-sodium alginate is dispensed, any floating spheres should be discarded and the rest of the spheres rinsed in tap water and drained ( Fig. 1 ). At this point, the spheres are ready to be tested for enzyme activity. If time is short, the spheres may be placed in tap water and put into a refrigerator until ready to be used.

Yeast spheres.

Designing an experiment

For the initial trial runs using the graduate method, students should fill a graduated cylinder with 0.3% H 2 O 2 . I generally use 50 mL cylinders with 5 mL 3% H 2 O 2 (the concentration of store-bought H 2 O 2 ) + 45 mL dH 2 O. Using forceps, or the loop end of the inoculating loop, one yeast sphere is dropped into the graduated cylinder. Students should start timing as soon as the sphere touches the bottom of the cylinder. Timing continues until the sphere reaches the surface. The used yeast sphere is disposed of and the experiment is repeated with a few more spheres to get several time samples. Students should use spheres that are close in size for all of their trials. For gas pressure sensor experiments, I use 5 g of yeast spheres in 50 mL of 1.5% H 2 O 2 and run the program for two minutes.

Once the basics of the set-up are understood, students are free to design an experiment to see what effect different variables will have on this enzymatic reaction. Make sure they write out their experimental design first before carrying out the experiment, including the control, what concentration(s) of substrate will be used, what temperature(s), how many trials, and how the data will be analyzed and displayed.

For initial runs for either the test stick or glucose oxidase method, I use one gram of yeast spheres in 10 mL of a 2.5% sucrose solution. At different time periods, glucose may be tested for by either dipping glucose test strips into the surrounding solution or taking out 0.2 mL of the solution and adding it to 1.8 mL of dH 2 O and 1 mL of glucose oxidase ( Appendix 2 ).

These are very easy and reliable enzyme experiments that enable students to collect data in a relatively short period of time. The graduated cylinder method for testing catalase is especially good for collecting large amounts of data that enable students to use statistics and, unlike similar yeast catalase experiments using paper disks and a yeast solution ( http://cibt.cornell.edu/labs-activities/labs/catalase/ ), the yeast spheres are easy to manipulate, and there is very little variability. I have used this procedure with students in class and with teachers in workshops, with positive results and comments ( Appendix 3 ). The gas pressure sensor method works nicely as well but requires more yeast spheres and takes a bit more time. Testing for invertase activity is a nice addition to a respiration/fermentation lab, and when used in conjunction with catalase, gives a nice comparison as to how enzymes, even from the same organism, may have different temperature and pH optima.

SUPPLEMENTAL MATERIALS

Appendix 1: Sample data

ACKNOWLEDGMENTS

The author declares that there are no conflicts of interest.

† Supplemental materials available at http://asmscience.org/jmbe