Chemistry Demonstrations

Elephant Toothpaste (Elementary School Demo)

What you need:

  • 12 oz plastic bottle
  • hydrogen peroxide (3%)
  • dish soap
  • dry yeast
  • warm water
  • baking sheet

What to do:

  1. Prepare yeast solution by adding dry yeast to warm water and wait a few minutes until it becomes frothy.
  2. Pour 2 inches of hydrogen peroxide (3%) into the bottle.
  3. Place bottle on baking sheet.
  4. Squeeze in a good squirt of dish soap.
  5. Pour in yeast solution (3 tablespoons).

Chemical Principle: Catalysis

A catalyst is a chemical compound that speeds up the rate of a reaction. 

Hydrogen peroxide (H2O2) is a reactive molecule that readily decomposes into water (H2O) and oxygen:

                                2H2O2 → 2H2O + O2(g)

In this experiment yeast is the catalyst causes decomposition and makes a big foamy mess!

Briggs-Rauscher Reaction – Yellow to Blue (College Demo)

What you need:

  • 30% H2O2
  • Soluble starch
  • KIO3
  • MnSO4•H2O
  • Malonic acid
  • Deionized water
  • 1 M H2SO4
  • Large beaker
  • Graduated cylinders (3)
  • Stir plate / stir bar

What to do:
1. Solution A: Prepare 100 mL of 9% H2O2 by diluting 30 mL of 30% H2O2
with 70 mL of deionized H2O.
2. Solution B: Prepare an acidified 0.2 M KIO3 solution by adding 10 mL of
1.0 M H2SO4 to 80 mL of deionized water. Dissolve 4.3 g KIO3 in this
solution and dilute to 100 mL.
3. Solution C: Prepare starch solution by dissolving 0.1 g of soluble starch in
90 mL of boiling deionized water. When cool, add 1.5 g malonic acid, 0.4
g MnSO4•H2O, stir and dilute to 100 mL.
4. Add 50 mL of Solution A to a clean beaker fitted with a stir bar. Next add
50 mL of Solution B and let solutions mix thoroughly. Once complete, add
50 mL of Solution C and let reaction stir. Upon addition of the final
solution, bubbles should appear. The solution will turn yellow then blue,
then colorless. This reaction will oscillate for 5-10 minutes.