Hydrolysis Water Splitting
Using a 9V battery, 2 electrodes and small gauge wire, you can split water into its component parts. This process is called hydrolysis. We add a small amount of salt to increase the conductivity of the water and an acid/base indicator to visualize the reaction.
The chemical formula of water is H2O. When the electrical current, produced by the battery, passes through the water, the water will split and the two electrodes will bubble. Hydrogen will appear at the cathode and the oxygen at the anode. The acid base indicator around the cathode will turn blue (because the free OH molecules raise the pH) and the area around the anode will turn pink (because the free hydrogen molecules lower the pH).
Looking at the formula for water, there are twice as many hydrogen atoms as oxygen. When hydrolysis occurs, twice as many hydrogen bubbles will be released as oxygen. You can visually see extra bubbles at the point where hydrogen is being released.
Hydrolysis experiments can be quantitative (how much hydrogen and oxygen are released?) or qualitative (can I visually see the reaction taking place?)