Steve Spangler's elephant toothpaste experiment demonstrates how potassium iodide can be used to catalyze hydrogen peroxide, creating water and oxygen. Food coloring and soap are added as visual aids. When the two liquids are mixed, the potassium ion reacts with the peroxide, liberating large amounts of oxygen. The soap traps this oxygen as bubbles, which boil out of the vessel like toothpaste squeezed energetically from a tube.Continue Reading
The original experiment used potassium iodide, which can cause irritation if it comes into contact with bare skin. In addition, the iodine produced can stain clothing and surfaces. A safer version of the experiment uses a solution of yeast and warm water, which liberates oxygen more slowly but produces a foam that is completely safe to handle. Most versions of the experiment aimed toward younger students use the yeast version to prevent accidents.
No matter which substance is used to catalyze the hydrogen peroxide, the process is exothermic, producing heat as a by-product. With the iodide reaction, the heat may be enough to warp plastic, so students should stand well back and protect any surfaces that might be damaged by excess heat. The slower reaction produces less heat, but it may still produce clouds of steam from the escaping foam.Learn more about Chem Lab