for some half cell reactions are given below. On the basis of these mark the correct answer.

Question

for some half cell reactions are given below. On the basis of these mark the correct answer. (a) (b) (c)

Philoid · Accepted Answer

In electrolysis of dilute sulphuric acid, the half reactions at cathode and anode are as follows,

Anode: 2H₂O (l) → 4H⁺ (aq) + O₂ (g) + 4e^–

4OH^– (aq) → 2H₂O (l) + O₂ (g) + 4e^–

The standard reduction potential of H₂ is higher than that of SO₄^2- ion, hence oxidation of H₂O takes place instead of sulphate.

Cathode: 2H⁺ (aq) + 2e^–→ H₂ (g)

Here the H⁺ ions are attracted to the cathode and are reduced to form H₂ gas.

For concentrated sulphuric acid, there is very low amount of water present, so at the anode, the sulphate ions get attracted and forms di-anion.

2SO₄⁻⟶S₂O₈²⁻+2e⁻ is the equation. Thus, at anode sulphuric acid gets oxidized, not water.

The correct options are (i) and (iii).