LAQ : Describe the principle of electrolysis of an aqueous solution of CuSO4 using Cu-electrodes

Question

Describe the principle of electrolysis of an aqueous solution of CuSO₄ using Cu-electrodes. 

Answer

The aqueous solution of CuSO₄ acidified with dilute H₂SO₄ is used as an electrolyte. This electrolytic solution contains H⁺, Cu²⁺ cations and SO₄^2- and OH^– anions.

H₂O ⇔ H⁺ + OH^–;

CuSO₄ ⇔ Cu²⁺+ SO₄^2-

Between the cations H⁺ and Cu²⁺, the Cu²⁺ ion has a greater tendency to be reduced. So Cu²⁺ ion in solution takes two electrons from the cathode and is reduced to copper and is adhered on the surface of the Cu cathode. Thus the weight of the Cu-cathode increases. Copper anode (is not inert) gives up two electrons and is oxidised to Cu²⁺ ion and remains in solution, the weight of Cu – anode decreases. The concentration of the electrolytic solution CuSO, remains constant.

Cathode reaction: Cu²⁺ + 2e → Cu (reduction)

Anode reaction: Cu-2e → Cu²⁺ (oxidation)