Breakdown of hydrogen peroxide.

Description:

A chemical (hydrogen peroxide) is shown to decompose (to produce oxygen and water) by capturing the gas evolved in bubbles using washing up liquid.  It can be shown that the reaction occurs at different rates with different materials.

Requires:

  • Potato or celery
  • Yeast
  • Washing up liquid
  • Hydrogen peroxide solution (3%, 6% or 9% for hair bleaching is suitable)
  • Container

Method:

Place a small amount of hydrogen peroxide solution in a container.  Add a few drops of washing up liquid and then some potato (or celery) pieces.  Compare the speed of bubble formation when yeast is added.  (Note: dissolve the yeast, either fresh or dried, in a little water.)

Principle:

The breakdown of hydrogen peroxide into water and oxygen is catalysed by catalase enzymes in plants and animals. You can see what a catalase enzyme looks like by clicking here.

Tip:

To make an impressive demonstration use a bottle with a small outlet to it and the bubbles will squirt up high into the air.

Other materials such as potassium iodide also catalyse this reaction.

A large amount of catalase can be found in animal liver

The breakdown of hydrogen peroxide into water and oxygen is catalysed by catalase enzymes in plants and animals.

Hydrogen peroxide naturally breaks down to water and oxygen, but very slowly. The catalase enzyme in yeast and other materials, such as potato and liver, speeds up the reaction greatly.

Hydrogen peroxide naturally breaks down to water and oxygen, but very slowly. The catalase enzyme in yeast and other materials, such as potato and liver, speeds up the reaction greatly.

Safety:

Hydrogen peroxide is a bleach. Take care not to spill it on clothes or skin (which will also turn white). Wash spilled solutions with plenty of water. White patches on skin will disappear after a day or two but might prickle for a while. Gloves and protective clothing are recommended precautions in addition to the usual eyewear.

Tags: Decomposition, breakdown, enzyme, catalysis, exothermic, reaction rates.