Kid-Friendly Elephant Toothpaste Demo


Students playing with kid-friendly elephant toothpaste
Kid-friendly elephant toothpaste is safe enough to touch. (Maine Dept. of Education)

The elephant toothpaste chemistry demonstration produces a steaming tube of foam that erupts like an elephant squeezing a giant tube of toothpaste. The classic demo isn’t appropriate for kids because it uses 30% hydrogen peroxide, but there is a safe, easy version, too. The kid-friendly elephant toothpaste demo uses ordinary household hydrogen peroxide (only 3%), dry yeast, and liquid dishwashing detergent. It’s a great project for getting kids interested in science, especially chemistry.

Materials

This project uses common, safe household materials:

  • Empty 16-ounce or 20-ounce plastic bottle
  • 3% hydrogen peroxide
  • 1-2 packets of dry yeast
  • Liquid dishwashing detergent
  • Warm water
  • Food coloring (optional)
  • Cookie sheet (optional)

If you don’t have an empty plastic bottle, any other container will work. However, you’ll get the best effect if the container has a narrow opening. You can find hydrogen peroxide, yeast, and dishwashing liquid at any grocery store. While you don’t need food coloring, the natural color of the reaction ranges from creamy to amber. Add blue if you want foam that looks more like toothpaste. You can place the bottle on a cookie sheet to catch the foam for easier clean-up.

Make the Elephant Toothpaste

You don’t need to measure your ingredients precisely for this project.

  1. Pour a cup of hydrogen peroxide into an empty plastic bottle. Use a funnel, if necessary.
  2. Add about 2 tablespoons of liquid dishwashing detergent to the bottle. If desired, add 8 drops of food coloring. Swish the liquid around to mix it well.
  3. Mix yeast with warm water in a separate container. It helps to use a paper cup, so you can pinch the rim to make a spout. Give the yeast mixture a couple of minutes to activate before performing the demo.
  4. When you’re ready for the eruption, set the bottle on the cookie sheet and pour the yeast mixture into the bottle.
  5. Enjoy the reaction!

How It Works

Hydrogen peroxide (H2O2) is a common household disinfectant and bleach that decomposes into water and oxygen. The chemical reaction is:

2H2O2(l) → 2H2O(l) + O2(g)

Ordinarily, this reaction proceeds slowly, but yeast makes an enzyme called catalase that catalyzes the reaction so it happens quickly. The decomposition reaction is exothermic, meaning it produces heat. This makes the foam and bottle warm to the touch, but not hot enough to cause burns. The liquid detergent traps the oxygen gas in bubbles. The bubbles are lighter than the liquid, so they force their way out of the bottle as foam.

Tips for Success

  • Be sure to mix warm water with the yeast rather than hot or cold water. Yeast won’t activate in cold water and may die if the water is too hot. Warm water also speed the chemical reaction and gives the best effect.
  • While 3% peroxide is fairly safe, it can discolor fabrics.
  • If children touch the foam, be sure they wash their hands afterward to avoid ingesting dishwashing soap.

Christmas Tree Elephant Toothpaste

This reaction can also be used as a holiday demonstration. Ideally, use an Erlenmeyer flask as the container because it has a cone shape like a holiday tree. Another option is to invert a funnel over a bottle and decorate the exterior like a Christmas tree. Add green food coloring to the bottle, so when it foams up it makes a green “tree.”

Original vs Kid-Friendly Elephant Toothpaste

Both the classic project and the kid-friendly version work by the decomposition of hydrogen peroxide. Potassium iodide (KI) catalyzes the original reaction, while catalase from yeast catalyzes the kid-safe demo. The original demo uses much more concentrated hydrogen peroxide, so it produces more foam. However, the concentrated solution can cause chemical and thermal burns and the foam it produces contains steam.

References

  • Dirren, Glen; Gilbert, George; Juergens, Frederick; Page, Philip; Ramette, Richard; Schreiner, Rodney; Scott, Earle; Testen, May; Williams, Lloyd. (1983). Chemical Demonstrations: A Handbook for Teachers of Chemistry. Vol. 1. University of Wisconsin Press. Madison, Wisconsin. doi:10.1021/ed062pA31.2
  • Elephant’s Toothpaste.” University of Utah Chemistry Demonstrations. University of Utah.
  • Hernando, Franco; Laperuta, Santiago; Kuijl, Jeanine Van; Laurin, Nihuel; Sacks, Federico; Ciolino, Andrés (2017). “Elephant Toothpaste”. Journal of Chemical Education. 94 (7): 907–910. doi:10.1021/acs.jchemed.7b00040

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