JEE MainChemistryElectrochemistry
Match List I with List II for the half-cell reactions of a lead storage battery. List I List II A. Anode reaction during discharging I. Pb(s) + SO ₄²⁻ (aq) PbSO ₄ (s) + 2 e ^- B. Cathode reaction during discharging II. PbO ₂ (s) + SO ₄²⁻ (aq) + 4 H ^+ (aq) + 2 e ^- PbSO ₄ (s) + 2 H ₂ O(l) C. Anode reaction during charging III. PbSO ₄ (s) + 2 H ₂ O(l) PbO ₂ (s) + SO ₄²⁻ (aq) + 4 H ^+ (aq) + 2 e ^- D. Cathode reaction
Options
- AA-I, B-II, C-IV, D-III
- BA-II, B-I, C-III, D-IV
- CA-III, B-IV, C-I, D-II
- DA-I, B-II, C-III, D-IV
Correct answer
D. A-I, B-II, C-III, D-IV
Step-by-step solution
During the discharging of a lead storage battery, it acts as a galvanic cell. At the anode, oxidation of lead occurs: Pb(s) + SO ₄²⁻ (aq) PbSO ₄ (s) + 2 e ^- (A matches I). At the cathode, reduction of lead(IV) oxide occurs: PbO ₂ (s) + SO ₄²⁻ (aq) + 4 H ^+ (aq) + 2 e ^- PbSO ₄ (s) + 2 H ₂ O(l) (B matches II). During the charging of the battery, it acts as an electrolytic cell and the reactions are reversed. The positive plate (which was the cathode) now acts as the anode, where oxidation takes place: PbSO ₄ (s) +