Science

Elephant Toothpaste Experiment

Watch a giant foam tower erupt from a single bottle as hydrogen peroxide breaks apart and releases oxygen in a spectacular exothermic reaction.

Medium · 30 minutes

Introduction

Elephant toothpaste gets its name because the foam that shoots out is so huge it looks like it could belong to an elephant. But this is not just a cool explosion—it is a real chemical reaction you can control.

This experiment teaches you how catalysts speed up reactions, why heat is released when chemicals change, and how oxygen gas turns a liquid into an enormous pile of foam right before your eyes.

The Why

Hydrogen peroxide naturally breaks down into water and oxygen gas, but it does so very slowly on its own. Adding a catalyst, like yeast mixed with warm water, gives the reaction a shortcut and makes it happen almost instantly. The oxygen gas escapes so quickly that it gets trapped inside the dish soap, creating thousands of bubbles stacked into thick foam. The reaction is also exothermic, meaning it releases heat you can feel when you touch the foam carefully after it settles.

Step-by-Step Instructions

1
Put on safety goggles and gloves before handling the hydrogen peroxide.
2
Set the bottle in the center of the tray so the foam stays contained.
3
Add the dish soap and a few drops of food coloring directly into the bottle.
4
Pour the hydrogen peroxide into the bottle and swirl it gently to mix.
5
In a separate cup, stir the yeast packet into the warm water for about 30 seconds until it dissolves.
6
Pour the yeast mixture quickly into the bottle and step back right away.
7
Watch the foam shoot up fast and notice how warm it feels when you touch it carefully after it slows down.
8
Discuss what happened: what was the catalyst, where did the heat come from, and what was inside all those bubbles?

Materials List

1/2 cup of 6% or 12% hydrogen peroxide (found at beauty supply stores)
1 packet of dry active yeast
3 tablespoons of warm water
A squirt of dish soap
A few drops of food coloring
A 16-ounce or larger plastic bottle or graduated cylinder
A tray or baking sheet for easy cleanup
Safety goggles and gloves

Safety First!

Always have an adult handle and pour the hydrogen peroxide, which can irritate skin and eyes. Wear safety goggles and gloves throughout the experiment. The foam is warm and safe to touch after it fully settles, but do not let liquid contact eyes or skin during the reaction. Dispose of the foam and any leftover liquid by rinsing them down a drain with plenty of water.

Challenge Mode

Try two different concentrations of hydrogen peroxide—3% from the drugstore and 6% or higher from a beauty supply store—and compare how tall each foam tower grows.