This demonstrations is called Elephant’s Toothpaste because the chemical reaction produces a large foamy mess that looks like toothpaste squirting out of a tube. It is so big that only an elephant could use toothpaste this large. It is, of course, not toothpaste so please do not try to brush your teeth with it! The kids safe version below is harmless but certainly wouldn’t taste very good.
Our EXTREME Scientists do the Elephant’s Toothpaste demonstration in our Extreme Science Theater located on the lower level of the science center. So if you want to see it again just come on in!
What is Elephant Toothpaste?
This large demonstration uses hydrogen peroxide (H2O2), sodium iodide (NaI) and soap. First we pour in the hydrogen peroxide, then the soap and finally the sodium iodide.
The hydrogen peroxide used in the demonstration is 30% hydrogen peroxide. This is 10 times stronger than the hydrogen peroxide that you have in your medicine cabinet. That is usually 3% hydrogen peroxide, and your local salon probably uses 6%. The 30% hydrogen peroxide is not something you would put on a cut or scrape, but it works perfectly for this demonstration. The sodium iodide reacts with the hydrogen peroxide (H2O2) by removing an oxygen atom. This essentially produces water and oxygen gas (H2O + O2). The oxygen gas produced gets trapped in the soap which produces the big ball of foam. The reaction produces oxygen gas, water and iodine. That is why the foam has a yellow color. If you were to touch this foam, your hand would be stained yellow just as if you put iodine on your skin.
Since you can’t get these materials at home we have a Kids Safe version of this demonstration that you can do at home or in the classroom! Do this at your next family night, slumber party or birthday party. It is fun, safe and cool to watch.
Kid-Safe Elephant Toothpaste
What you need:
12 oz plastic bottle
hydrogen peroxide (3%)
What to do:
Prepare yeast solution by adding dry yeast to warm water and wait a few minutes until it becomes frothy.
Pour 2 inches of hydrogen peroxide (3%) into the bottle.
Place bottle on baking sheet.
Squeeze in a good squirt of dish soap.
Pour in yeast solution (3 tablespoons).
The yeast contains an enzyme called Catalase that breaks down hydrogen peroxide (H2O2) into oxygen gas and water. The oxygen gas gets trapped by the soap, and you get a large foamy solution that squirts out of the top of the bottle!
The cool thing about this activity is that the enzyme Catalase can also be found in potatoes, dogs and even us! We have the same enzyme in our bodies. That is why you see the 3% hydrogen peroxide bubble when you put it on a cut or scrape. The oxygen released is what kills the germs in the cut. We have this enzyme because we naturally produce low amounts hydrogen peroxide as a byproduct of oxidative metabolism (the way that a cell gains useful energy). Our cells need energy, but low amounts of hydrogen peroxide are produced and need to be neutralized through enzymes like Catalase.