Here we investigate electrolysis and try to explain our findings with a few diagrams and animations. In this diagram we are showing how heating causes the ions to become mobile, and then the electric field causes the ions to separate.
This allows us to separate elements in a molten ionic compound.
Electrolysing molten compounds:
In this example, molten lead bromide is electrolysed.
At the cathode, lead ions gain electrons and become atoms, therefore they are being reduced.
At the anode, bromide ions lose electrons and become pairs of atoms (diatomic molecules), therefore they are being oxidised.
Making aluminium
Answer the questions below when you have watched the animation:
Aqueous electrolysis
Adding water complicates electrolysis because introducing water introduces hydrogen (H+ aqueous) and hydroxide ions (OH- aqueous) to the solution.
The effect of this can be seen in the results table below.