Mammoth Memory

Example 3 - Electrolysis of water

The chemists even tried electrolysis on water.

Electrodes were put into water and covered with test tubes to capture gas


When they tested the tubes after performing electrolysis on water …          

They noticed that the anode gave off oxygen and the cathode gave off hydrogen
… they found hydrogen in one tube and oxygen in the other.        

What was really interesting was that when they looked closely at the test tubes, twice as much volume of hydrogen had been created as there was oxygen. This is because there are two hydrogen atoms for every one oxygen atom in a molecule of water – as indicated by the formula, H2O.

Water was giving off more hydrogen than oxygen, twice more in fact giving the formula H2O

See the examples at the end of this section for more detailed information, but remember …

  • A mole of oxygen (O2) = 24 litres volume
  • A mole of hydrogen (H2) = 24 litres volume
More Info