Elephant Toothpaste

Purpose:

To demonstrate the effect of a catalyst on the decomposition of hydrogen peroxide.

Materials:

• Food coloring (optional)
• Large plastic tub
• 1L graduated cylinder

Reagents:

• 30% Hydrogen peroxide (H₂O₂)
• Saturated potassium iodide (KI)
• Liquid detergent/dish soap

Hazards and PPE:

• Hydrogen peroxide at high concentrations is highly combustible. Store and handle with care.
• Wear approved safety goggles and gloves.

Protocol:

Demonstration

1. Place a 1L graduated cylinder into the plastic tub.
2. Add 50mL 30% H₂O₂ to the cylinder.
3. Add 50mL liquid detergent to the cylinder and mix by swirling.
4. Food coloring may be added to alter color.
5. Add 50mL of Sat. KI solution to the cylinder.
   1. Reaction will occur quickly and copious amounts of foam with result.

Additional Notes:

• A 6L Erlenmeyer flask can be used in place of the graduated cylinder. Use double volume of all solutions for this variation.

Disposal:

• Foam/excess solutions can be washed down the drain with excess water.

Reactions:

• H₂O_2(aq) + I⁻_(aq) → H₂O_(l) + IO⁻_(aq)
• H₂O_2(aq) + IO⁻_(aq) → H₂O_(l) + O_2(g) + I⁻_(aq)
• Overall: 2H₂O_2(aq) + 2H₂O_(l) + O_2(g)

Citations:

1. ICE, Chemical Demonstrations Workshop, University of Arizona, 1987.

Videos:

• Bytesize Demo: Elephant's Toothpaste

  BytesizeScience