Wednesday, October 11, 2017

Day 7 of 13 Days of Halloween: Pumpkin Themed Elephant Toothpaste

Every year I need to post about elephant toothpaste.  It is the ultimate Halloween Chemical Reaction.  I fell in love with this experiment a few years back.  I like to look at it as a step up from the classic vinegar and baking soda reaction we always see.  Vinegar and baking soda is great, but lets take it up a notch.

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

When my son was in 5th grade we did Pumpkin Themed Elephant Toothpaste for his class party.  This worked out so well.  Instead of doing the typical crafts and bingo we pulled out the safety goggles and gloves and made erupting pumpkins.  The kids had a blast!   All you do is use pumpkins instead of containers.  See directions and tips below.

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 use 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. Elephants 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 that contain enzyme catalysts that quickly break the hydrogen peroxide into a water molecule and an oxygen atom.   We add soap to elephants toothpaste to make it more foamy.
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.  Once the yeast water mixture is poured in with the soapy hydrogen peroxide the magic happens.  The oxygen atom will separate from the hydrogen peroxide and 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 temperature of the water before the experiment and of the foam after to see the temperature rise.  You can also touch it to feel the warmth.

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 years old 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 there 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.

Goggles and gloves must be warn 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 the ability of your students before beginning. 

Directions from Steve Spangler Science

I like the recipe he has.  He does a great job explaining it and giving directions.  I also recommend putting puppy training pads underneath.  Yes, that is right puppy training pads.  They are so absorptive and great for spills.  I try to always have a box on hand for experiments.

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 then discover elephant toothpaste by creating their own 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 add it in to your curriculum.


  1. Love these Halloween science blog posts - perfect for STEM days!

  2. Thank you so much. Students will definitely have a memorable scientific experience.