No, the copper sulphate solution does not completely become sulphuric acid, but the concentration of sulphuric acid may increase under certain conditions.
What actually happens during electrolysis?
When electrolysis of CuSO₄ solution is carried out using inert electrodes (like platinum or graphite):
- At the cathode (reduction):
Cu²⁺ + 2e⁻ → Cu (solid)
(Copper ions are removed from the solution)
- At the anode (oxidation):
2H₂O → O₂ + 4H⁺ + 4e⁻
(Water breaks down, releasing H⁺ ions)
Why does it seem like sulphuric acid is forming?
- As Cu²⁺ ions are removed and H⁺ ions increase, the solution becomes more acidic.
- The remaining SO₄²⁻ ions combine with H⁺ ions, effectively forming H₂SO₄ (sulphuric acid) in solution.
Important Condition:
- If copper electrodes are used, then:
- Copper dissolves at the anode (Cu → Cu²⁺ + 2e⁻)
- Cu²⁺ ions are replenished
→ So, no significant increase in sulphuric acid concentration
Key Takeaway:
The solution doesn’t fully convert into sulphuric acid, but it becomes more acidic (rich in H₂SO₄) when inert electrodes are used due to the increase in H⁺ ions.