There are several different versions of this “recipe” science project out there. This is the one we did:
3 tablespoons warm water
1 tablespoon dry yeast
1/2 cup hydrogen peroxide 6% (we only had 3% so the results were not as good as we wanted but still plenty good to keep the kids entertained and learning)
Squirt of dish soap
An empty 16 oz water bottle or soda bottle (cleaned out and empty)
Mix the warm water and dry yeast in a small bowl and put off to the side.
Pour the dish soap, food coloring and hydrogen peroxide into the bottle. Set the bottle in the middle of a baking pan or large cookie sheet. To be safe – put on safety goggles before the next step!
Use a funnel to make this easier – pour the contents of the small bowl through the funnel into the bottle. Then watch the bubbles grow and grow for about a half hour. The bottle will also be warm to the touch.
Each tiny foam bubble fills with oxygen. The yeast acts as a helper and removes the oxygen from the hydrogen peroxide very fast – creating tons and tons of bubbles. The heat is created as a result of the exothermic reaction.
The foam is safe – it is just water, soap and oxygen – it can be simply cleaned up and poured down the drain.