Elephant toothpaste is a science experiment that creates a fountain of foam. The elephant toothpaste experiment uses simple chemicals (though many formulas exist), but get ready for a mess. A child-friendly version works for elementary school audiences.
Place the cylinder in the middle of a cake tin. Cover the table with plastic bags in case the reaction spills over.
Put on gloves.
Put each ingredient in a small cup. Measure about 80 ml hydrogen peroxide, 40 ml of Dawn dish detergent, and 10 to 15 ml of potassium iodide. Your proportions can vary depending on the concentration of the ingredients. If possible, try the experiment before you perform it for a science lab or audience so you can figure out the correct proportions.
Introduce the reaction with a joke, such as telling students that you have a pet elephant and that you used to always run out of toothpaste before you accidentally mixed the chemicals in front of you on the table.
Pour the hydrogen peroxide and the detergent into the cylinder, and mix them. If desired, add a few drops of food coloring.
The tricky part comes next. Tip the iodine into the cylinder, and stand back. The reaction will take place very quickly, shooting out hot foam.
Once the foam has cooled, clean it up with water.
For a more kid-friendly, though less dramatic, version, use common household hydrogen peroxide, dish soap and a packet of dried yeast. The reaction takes place more slowly, but it doesn't produce as much heat and is safe for kids to play with.
Don't take off your gloves before cleanup. The iodine will stain your skin. If you are doing the yeast version, you can let your students touch the cylinder and feel the warmth created by the reaction. Use their observations to launch a discussion of exothermic reactions.