Question 5(iii)
(a) State whether the following statements are true or false. Justify your answer.
(1) Electrolysis of molten lead bromide is considered to be a redox reaction.
(2) Copper is a good conductor of electricity but it is a non-electrolyte.
(b) State the reaction occurring at the anode during electrolysis of copper sulphate solution using a copper anode and platinum anode respectively.
(a) (i) True
Electrolysis of molten lead bromide involves oxidation and reduction reactions and hence is a redox reaction.
Dissociation of lead bromide
PbBr2 ⇌ Pb2+ + 2Br1-
Reduction reaction at cathode:
Pb2+ + 2e- ⟶ Pb
Oxidation reaction at the anode:
Br1- - 1e- ⟶ Br
Br + Br ⟶ Br2
(a) (ii) True
Copper does not undergo chemical decomposition due to flow of electric current through it. Hence, copper is a good conductor of electricity but it is a non-electrolyte.
(b) Reaction at anode [active copper] : Cu - 2e- ⟶ Cu2+
Reaction at anode [inert platinum] : OH1- - 1e- ⟶ OH x 4
4OH ⟶ 2H2O + O2