When metallic copper is shaken with a solution of a copper salt, the reaction Cu + Cu^2+ 2Cu^+ proceeds. When equilibrium is established at 298 K, [Cu^2+]/[Cu^+]^2 = 1.667 × 10^6 M^–1. If the stan

Question

When metallic copper is shaken with a solution of a copper salt, the reaction Cu + Cu^2+ <=> 2Cu^+ proceeds. When equilibrium is established at 298 K, [Cu^2+]/[Cu^+]^2 = 1.667 × 10^6 M^–1. If the standard potential of the Cu^2+ \| Cu half-cell is +0.3376 V, what is the standard potential of Cu^+\| Cu half-cell? (Given: 2.303RT/F = 0.06, log 2 = 0.3, log 3 = 0.48)

Prashant Kotian · Accepted Answer

Correct answer: C. The equilibrium constant for Cu + Cu^2+ <=> 2Cu^+ is K = [Cu^+]^2 / [Cu^2+] = 1 / (1.667 × 10^6) = 6 × 10^–7. E°_cell = 0.06 * log(K) = 0.06 * (log 6 - 7) = 0.06 * (0.78 - 7) = -0.3732 V. E°_cell = E°_Cu2+/Cu+ - E°_Cu+/Cu. Using ΔG relations, E°_Cu2+/Cu+ = 2E°_Cu2+/Cu - E°_Cu+/Cu. Substituting this into the E°_cell equation: -0.3732 = 2(0.3376) - 2E°_Cu+/Cu. 2E°_Cu+/Cu = 0.6752 + 0.3732 = 1.0484 V. E°_Cu+/Cu = 0.5242 V. Therefore, correct answer is C.

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