Foamy Fun: The Science Behind Elephant Toothpaste | Small Step for STEM (2025)

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Have you ever heard of elephant toothpaste? If you haven’t, you’re in for a real treat today! It’s a unique chemical reaction that has a little twist to it (the help of a catalyst to speed things up).

The elephant toothpaste experiment demonstrates a fun chemical reaction by quickly breaking down hydrogen peroxide into water and oxygen with dish soap to make it foamy.

This is a messy experiment, and one that is a ton of fun! Let’s get started!

How to make the Foamy Fun Elephant Toothpaste STEM experiment

Supplies you will need

For this experiment, you’ll need:

• 2-liter plastic bottle
• Dry yeast (1 tablespoon)
• Warm water (3 tablespoons)
• Hydrogen peroxide (1/2c)
• Bowl
• Liquid dish soap
• Food coloring
• Funnel
• Measuring cup (1/2c)

Before you start

You’ll want to do this outside or somewhere that you can easily clean up. It’s messy!

Instructions

Here is how to do this experiment with your child:

Step 1: Pour hydrogen peroxide into bottle

Measure 1/2 cup of hydrogen peroxide. Use a funnel to carefully pour it into the 2-liter bottle.

Step 2: Add dish soap

Add a little bit of dish soap to the bottle.

Next, add a few drops of the food coloring of choice. If you want the end result to look like toothpaste, run the food coloring down the sides of the bottle like the image below.

Step 3: Mix warm water and yeast in separate bowl

Next up, add 3 tablespoons of warm water and 1 tablespoon of yeast to the bowl. Stir the mixture for about a minute.

Step 4: Add yeast mixture to 2-liter bottle

Using your funnel, carefully add the yeast mixture to the 2-liter bottle. The reaction will start and overflow out of the bottle!

If the reaction doesn’t quite make it to the top of the bottle, you can add more hydrogen peroxide using the funnel.

The STEM behind the Foamy Fun Elephant Toothpaste experiment

This experiment teaches:

• Chemical reactions
• Catalysts
• Gas production and pressure

How it works

The elephant toothpaste experiment demonstrates a fun chemical reaction by quickly breaking down hydrogen peroxide into water and oxygen with dish soap to make it foamy.

Hydrogen peroxide already breaks down into water and oxygen over time, but it’s a slow reaction. In our experiment, we use a catalyst, yeast, to speed up the reaction into an explosive one.

Since the reaction occurs quickly with the help of the yeast, the reaction generates a lot of oxygen in a short amount of time. The dish soap traps the gas and creates a lot of foamy mixture.

As the pressure from the oxygen builds up inside the container, the soapy foam, which looks like toothpaste, is forced out through the bottle opening.

Chemical reactions

Even though making an explosive elephant toothpaste looks super cool, we’re actually viewing a chemical reaction take place in real time!

The elephant toothpaste experiment demonstrates hydrogen peroxide breaking down into water and oxygen. In this experiment, the hydrogen peroxide is what is known as a reactant, which means it’s the substance in the chemical reaction that is undergoing change.

Hydrogen peroxide (H2O2) naturally breaks down into water (H2O) and oxygen (O2) over time, but who has time to wait for that? So, we speed things up in our chemical reaction.

How do we speed up the chemical reaction? With the help of a catalyst!

Catalysts

A catalyst is a substance that pushes the chemical reaction to react faster without being consumed or altered during the reaction.

In our experiment, the yeast is the catalyst.

Yeast contains an enzyme called catalase. Catalase is actually very important in the bodies of anything that lives in the presence of oxygen, ourselves included! In mammals, catalase is primarily found in the liver.

Catalase prevents hydrogen peroxide from accumulating in our bodies and damaging our tissues, since peroxide is produced by lots of different metabolic reactions found in our bodies.

So without it, we’d be in big trouble!

In this experiment, we’re using yeast (catalase) to quickly break down the hydrogen peroxide in the elephant toothpaste to start the chemical reaction.

Gas production and pressure

Since we’re breaking down the hydrogen peroxide with the yeast, or catalyst, very quickly, that means that there is a rapid production of oxygen gas that creates pressure inside of our bottle.

Gas takes up a lot more volume than a liquid. As the liquid peroxide breaks down quickly, the gas oxygen produced expands quickly and significantly.

The soap makes the reaction foamy by trapping the oxygen bubbles as they are produced, which creates the amazing foam part of the demonstration.

All of that expansion creates a lot of pressure inside of the bottle and it eventually erupts out of the bottle.

The more gas produced, the greater the pressure, and the bigger the eruption!

More experiments about chemical reactions to try out with your child

• Rev Up with Engineering Fun: Build a Chemical Reaction Car!
• Fizz, Pop, Inflate: The magical balloon experiment with a chemical reaction
• The Fizzing Lemon Science Experiment
• The Fizzing Paint Science Experiment

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