Catalytic Decomposition of Hydrogen Peroxide by Iodide

"Elephant's Toothpaste"

Large graduated cylinder (500 mL) or 2 liter soda bottle, goggles, plastic tray or sheet


1. Place graduated cylinder or soda bottle in a plastic tray or on a large sheet of plastic.

2. Pour ~50 mL of 30% hydrogen peroxide into the cylinder or bottle.

3. Add a squirt of dishwashing detergent; agitate slightly.

4. Add ~10 mL of potassium iodide solution OR 1/4 spoonful of solid potassium iodide. (Note: The reaction is much faster with the KI solution.) Step back quickly after adding the potassium iodide.

  1. L. R. Summerlin and J. L. Ealy, Jr. Chemical Demonstrations, A Sourcebook for Teachers, Washington D. C., 1985, p.71.

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