Pumpkin Themed Elephant Toothpaste Classroom Lab Experiment

One of the most exciting chemical reactions to try out during Halloween is Elephant Toothpaste. I personally find this experiment to be a more advanced version of the classic vinegar and baking soda reaction. While vinegar and baking soda are still great, taking things to the next level is always fun.

There are different versions of this experiment.  One is kid-friendly, and one is not.  This is the kid-friendly version.

Pumpkin Themed Elephant Toothpaste is a great science activity and perfect for a class party.  Instead of doing the typical crafts and bingo, pull out the safety goggles and gloves and make erupting pumpkins.  The kids will have a blast!   All you do is use pumpkins instead of containers.  The below pictures show pie pumpkins.  They are inexpensive and the perfect size.  See directions and tips below.

What Makes it Special?

The best part is the foam that rises.  I also like that it teaches about molecules in a way that kids can understand.  The reaction is also exothermic.  This means it gives off energy in the form of heat.  The foam will be nice and warm after the eruption.  I have students place thermometers in the foam.

What is happening?

This reaction involves using hydrogen peroxide.  The chemical formula is H202.  We are most used to the chemical formula of water (H20).  That extra oxygen on H202 is a weak bond.  It is very fragile and will easily separate, becoming H20 and 0.  That is why you need to keep H202 stored properly. Elephant toothpaste happens when we speed up the reaction.  We can speed up the reaction by using a catalyst. 
The purpose of a catalyst is to speed up the breakdown of molecules into simpler parts.  The catalyst used in this experiment is yeast.  Yeast are living organisms with enzyme catalysts that quickly break hydrogen peroxide into water molecules and oxygen atoms.  We add soap to elephant toothpaste to make it foamier.

In this experiment, the yeast must be activated by placing it in warm water.  The warm water will take the yeast out of the dormant state.  The magic happens once the yeast water mixture is poured in with the soapy hydrogen peroxide.  The oxygen atom will separate from the hydrogen peroxide, mix with the now soapy water, and rise out of the container.  When the bond breaks, heat will be given off.  You can take the water temperature before the experiment and the foam after to see the temperature rise.  You can also touch it to feel the warmth. Please wear gloves to be extra safe.

What kind of hydrogen peroxide should I use?

The hydrogen peroxide in the first aid section will not be strong enough for big results.  It is very diluted.  Go ahead and try it for comparison with the students.  It is still very fun.  The best hydrogen peroxide comes from the salon store.  It is sold in different dilutions.  I have found that 20 volume is great with younger kids, and then for 8-year-olds on up, go for the 40 volume.  The higher the volume, the more irritating to the skin it can be, so keep that in mind.  All they really do with it is pour it into the large container, so their contact with it is limited.  It is great to test the different volumes with the kids and talk about what concentration means.  The 40 volume has a larger concentration of hydrogen peroxide; therefore, more oxygen is being released.

Safety  

Goggles and gloves must be worn during the experiment.  Hydrogen peroxide can be irritating to the skin.  After the experiment, you will have a mixture of soapy water with yeast.  Students can touch that with their hands.  It is a warm, fluffy foam.  Be careful of spills, and look at your students' abilities before beginning. 

Explore, Investigate, Discover

Here is a great activity for students to explore the reaction further. Students will investigate elephant toothpaste by following the scientific method. They will answer the question: Does increasing the concentration of hydrogen peroxide affect the temperature of elephant toothpaste? Students will explore further by creating their own elephant toothpaste investigation. 

This can be completed as a class, in groups, or as a science fair project. The journal will take you step by step through the process. It also includes an elephant toothpaste assessment.  This is a great way to meet the standards.

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