Aqueous CuSO 4 is electrolysed with inert electrodes. The reduction potentials are: (i) 2 H + + 2 e − → H 2 ; E ∘ = 0.00 V (ii) Cu 2 + + 2 e − → Cu ; E ∘ = 0.34 V (iii) O 2 + 4 H + + 4 e − → 2 H

Question

Aqueous CuSO 4 ​ is electrolysed with inert electrodes. The reduction potentials are: (i) 2 H + + 2 e − → H 2 ​ ; E ∘ = 0.00 V (ii) Cu 2 + + 2 e − → Cu ; E ∘ = 0.34 V (iii) O 2 ​ + 4 H + + 4 e − → 2 H 2 ​ O ; E ∘ = 1.23 V (iv) S 2 ​ O 8 2 − ​ + 2 e − → 2 SO 4 2 − ​ ; E ∘ = 2.01 V Select the correct statement(s):

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At the cathode the species with the higher reduction potential is reduced: $Cu^{2 +}$ (0.34 V) beats $H^{+}$ (0.00 V), so $Cu$ is deposited: (A) true, (B) false.

At the anode the species with the lower reduction potential (easier to oxidise) goes first: water (1.23 V) rather than sulphate (2.01 V): (C) true, (D) false.

Answer: (A), (C).

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