C4.3.4 - Electrolysis of Aqueous solutions

• The ions discharged when an aqueous solution is electrolysed using inert electrodes depend on the relative reactivity of the elements involved.
• Explain what will be produced at the negative electrode (cathode) and how this is linked to the break down of water molecules.


  If the metal element formed during electrolysis is more reactive than hydrogen, then hydrogen will be produced at the cathode. If the metal element formed is less reactive than hydrogen, then the metal is produced at the cathode.
• Explain what will be produced at the positive electrode (anode) and how this is linked to the break down of water molecules.

  Two ions are attracted to the anode. The hydroxide ions and halide ions are attracted to the anode. If both are present, then a halogen is formed. If no halide ions are present, then the hydroxide ions are  discharged, and oxygen is formed.