Public Science – Elephant Toothpaste!

I hit the streets again and did some elephant toothpaste demonstrations with passersby in front of a really cool mural near downtown Houston. Check out the video below!

Elephant toothpaste is getting to be a really popular science demo! It is a chemical reaction using hydrogen peroxide and a catalyst to increase the release of oxygen. The oxygen in caught in dish soap, creating the foam. I use potassium iodide as the catalyst and a really strong hydrogen peroxide for a really big effect, but those chemicals require careful handling. You can try the demonstration safely at home using the instructions below!

Materials

• Empty plastic bottle, or experiment with different sizes and shapes of containers!
• Dry yeast packet (found on the baking aisle of the grocery store)
• Warm water
• Liquid dish soap
• 1/2 cup 3% or 6% hydrogen peroxide
• Measuring cups 
• Measuring spoons
• Safety glasses
• Plastic sheet or container to catch the foam . . . or try it outside!

Procedure

• Use safety glasses because hydrogen peroxide can irritate your eyes.
• Gloves are a good idea too, at least for clean up!
• Place your plastic bottle on your plastic sheet or container, or do the experiment somewhere that will be okay if you have a spill.
• Mix one tablespoon of yeast and three tablespoons of warm water together. Stir for about 30 seconds. Set aside.
• Measure 1/2 cup of hydrogen peroxide, and carefully pour it into the bottle.
• Add a nice big squirt of dish soap into the bottle and give it a light swirl to mix. Soap creates the foam, so don’t skimp here!
• Add a few drops of food coloring directly into the hydrogen peroxide, Or if you want to give your foam stripes like toothpastes, put the drops along the inside rim of the bottle’s mouth. Let them drip down the inside of the bottle without mixing them. 
• Pour the yeast mixture into the bottle, and watch your reaction!

Hopefully, you saw lots of bubbles and foam when doing your demonstration! When the hydrogen peroxide comes into contact with the yeast it starts breaking down into water and oxygen. Oxygen is a gas and it gets trapped as bubbles in the soap, creating the foam. The reaction continues as long as there is some hydrogen peroxide and yeast left.

You can try this with different-shaped containers, as you see me do in the video above! What happens if you use a bottle with a narrower or wider neck, or a container with no neck? Have fun!