(i) At the cathode, the following reduction reaction occurs to produce H₂ gas.

H⁺(aq) + e^- → 1/2 H₂(g)

At the anode, the following processes are possible.

2H₂O(l) → O₂ + 4H⁺ + 4e^- ; E° = +1.23V  ...(i)

2SO₄^2-(aq) → S₂O₆^2-(aq) + 2e^- ; E° = +1.96 V  ...(ii)

For dilute sulphuric acid, reaction (i) is preferred to produce O₂ gas. But for concentrated sulphuric acid, reaction (ii) occurs.

(ii) At cathode: The following reduction reactions compete to take place at the cathode.

Cu²⁺(aq) + 2e^- → Cu(s) ; E° = +0.34 V

H⁺(aq) + e^- → 1/2 H₂(g) ; E° = 0.00 V

The reaction with a higher value of E° takes place at the cathode. Therefore, deposition of copper will take place at the cathode.

At anode:

The following oxidation reactions are possible at the anode.

Cl^-(aq) → 1/2Cl₂(g) + e^- ; E° = 1.36 V

2H₂O(l) → O₂(g) + 4H⁺(aq) + 4e^-; E° = 1.23 V

At the anode, the reaction with a lower value of is preferred. But due to the over-potential of oxygen, Cl^- gets oxidized at the anode to produce Cl₂ gas.