Question

For the following cell, Zn(s) | ZnSO₄(aq) || CuSO₄(aq) | Cu(s) when the concentration of Zn²⁺ is 10 times the concentration of Cu²⁺, the expression for ΔG (in J mol⁻¹) is [F is Faraday constant; R is gas constant; T is temperature; E° (cell) = 1.1 V]
(A) 1.1F
(B) 2.303RT – 2.2F
(C) 2.303RT + 1.1F
(D) – 2.2F

Answer 1

According to Nernst equation,

E(cell) = E° (cell) - [2.303RT/nF][log([oxidised form of anode]/[oxidised form of cathode])]

E(cell) = 1.1 - [0.0591/2][log(10[Cu²⁺]/[Cu²⁺])]

E(cell) = 1.1 - [0.0295][log(10)]

E(cell) = 1.1 - 0.0295

E(cell) = 1.0705 V

ΔG = -(nFE(cell))

ΔG = -(2F*1.0705)

ΔG = -2.141 Jmol⁻¹ ≈ -2.2F

Hence, the answer is option (D).