Why does hydrogen get deposited at the cathode instead of sodium and chlorine at the anode instead of oxygen during the electolysis of aqueous sodium chloride. What is overvoltage?

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Solution

1. In the electrolysis of aqueous NaCl, H⁺ gets reduces at cathode and Cl^- gets oxidised at anode.
2. This is becuase,ability of H⁺ to get reduces is more than that of Na⁺ as it is more active or mobile as it is lighter that heavy Na⁺ cation.
3. Same is the case on anode where ability of Cl^- to get oxidised is more than OH^- .
4. Overvoltage : excess voltage required to remove an ion from its electrode.

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