Tuesday, October 20, 2015

13 Days of Halloween: Elephant Toothpaste

Day 2:  Elephant Toothpaste

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.

 Of course, the best part is the foaming 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 will give you some background information and 2 videos.  The full directions are at the end.  I like the recipe that Steve Spangler has on his website.

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.

20 Volume Hydrogen Peroxide Elephants Toothpaste

40 Volume Hydrogen Peroxide Elephants Toothpaste


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.  My 2nd grader did this for his science fair project and he did great with it.  He even took first place.  It is a great experiment.

Directions from Steve Spangler Science

I like the recipe he has.




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