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JAMB Chemistry 2008 Question 24

Question 24

Electrolysis

In recharging a lead-acid accumulator, the reaction at the cathode can be represented as

  1. A.Pb2+(aq) + SO4(aq)2− → PbSO4(s)
  2. B.Pb2+(aq) + 2e− → Pb(s)
  3. C.Pb2+(aq) + 2H2O(l) → PbO2(s) + 4H+(aq) + 4e−
  4. D.Pb(s) → Pb2+(aq) + 2e−
Show the answer and explanation

Answer: B (Pb2+(aq) + 2e− → Pb(s))

Explanation

During recharging the cathode is where reduction takes place: Pb2+ ions (from PbSO4) gain electrons and become lead metal again.