Question

Why do Cl⁻ ions get oxidised at anode in preference to H₂O during the electrolysis of an aqueous solution of sodium chloride?

Answer 1

1. During the electrolysis of an aqueous solution of sodium chloride, chloride ions (Cl⁻) get oxidised at the anode in preference to water, even though water has a lower standard oxidation potential.
2. This happens due to the high overvoltage required for the oxidation of water (to form O₂).

Hence, chloride ions are more easily discharged at the anode, releasing chlorine gas (Cl₂).