The Science Behind It

How It Works

Hydrogen peroxide (H2O2) is a reactive molecule that readily breaks down  into water (H2O) and oxygen:

The foam you made in this classic Elephant’s Toothpaste reaction is extra-special because each tiny foam bubble is filled with oxygen. In this demonstration, The yeast acted as a catalyst; a catalyst is used to speed up a reaction. It quickly broke apart the oxygen from the hydrogen peroxide. Because it did this very fast, it created lots and lots of bubbles.

Yeast needs warm water to reproduce, so the reaction won't work as well if you use cold water (no reaction) or very hot water (which kills the yeast).

The dishwashing detergent captures the oxygen that is released, making foam. Food coloring can color the film of the bubbles so you get colored foam.

Did you notice the bottle got warm. Your experiment also created a reaction called an Exothermic Reaction – that means it not only created foam, it created heat! However, the reaction just makes the solution warmer, not hot enough to cause burns.