Elephant Toothpaste

Materials

• an empty 16 oz. plastic soda or water bottle
• 1/2 cup 6% hydrogen peroxide
• Dish detergent
• Food coloring
• 1 teaspoon (or half a packet) of yeast dissolved in warm water

Activity Directions: Fill your soda bottle with the 1/2 cup of peroxide and then add a squirt or two of dish detergent. If you want, you can also add a squirt of food coloring to make things a bit festive. Now you need to prepare your yeast. Actually you have a couple of options, you could just pour the dry yeast into the bottle. This will create a surge of foam from the bottle with large bubbles. The yeast acting as a catalyst to release oxygen from the hydrogen peroxide. However, if you want a rich creamy foam of tiny bubbles, you should really add your teaspoon of yeast to a few tablespoons of warm water, then add the liquid to your bottle.

If you have ever made bread from scratch, you know that adding yeast to warm water allows the yeast to multiply into a somewhat smelly and foamy froth of more yeast cells. When you add this liquid to the peroxide you will get quite a surge of tiny soapy bubbles. The bubbly mixture is simply detergent, water, and oxygen filled bubbles and quite safe to touch. In fact you might observe that the foam is warm because this reaction is exothermic, meaning giving off heat.

Play around with the amount of peroxide, detergent, yeast and bottles to create the best geyser of foam!

The basic science here is that you have hydrogen peroxide, which really should be called hydrogen dioxide, since it is just a water molecule with an extra oxygen added on. Hydrogen peroxide is H2O2, water is of course H2O. By adding another chemical called a catalyst to the peroxide, you create a chemical reaction that releases the extra oxygen attached to the water molecule. If you mix in a little detergent you can capture that released oxygen in the form of bubbles.