Question

For a cell whose potential is -0.46 v with 3 moles of electrons exchanged, what is DG?

DG = -nFE°cell

a.) -133 kJ
b.) +133 kJ
c.) +133,170 kJ
d.) -6.65 x 10^-3

Answer 1

ΔG = -nEF

ΔG = Gibbs free energy change
n = moles of electrones participated in
E = Electrode potential
F = Faraday constant

By substituting,
ΔG = -(3 mol) x 96485 A S/ mol x (-0.46) V
= + 133149.3 J
= + 133 kJ

Hence the answer is "b".

Since ΔG is a positive value, the reaction is non spontaneous reaction.