Question

29. Explain how to predict the products of electrolysis of an aqueous solution

Answer 1

The products of electrolysis of an aqueous solution can be predicted using a discharge potential concept, as follows.

Example: Electrolysis of sodium chloride aqueous solution.

The solution contains Na⁺, H⁺ cations; Cl^- and OH^- anions.

The discharge potential of H⁺ is less than that of Na⁺, hence H⁺ ion will be discharged at cathode.

Therefore, the reaction at the cathode: 2H⁺ + 2e^- ----> H₂(g)

The discharge potential of Cl^- is less than that of OH^-, hence Cl^- ion will be discharged at the anode.

Therefore, the reaction at the anode: 2Cl^- ----> Cl₂(g) + 2e^-