Question

For spontaneity of a cell, which is correct ?

• A. ΔG = +ve, ΔE = +ve
• B. ΔG = 0, ΔE = 0
• C. ΔG = -ve
• D. ΔG = -ve, ΔE = 0

Answer 1

Answer: (C)

ΔG = -ve

Answer 2

For spontaneity of a cell, the correct statement is (C) $ΔG = -ve.$
The spontaneity of a cell reaction is determined by the Gibbs free energy change $(ΔG)$ of the reaction.
A negative $ΔG$ indicates that the reaction is spontaneous, meaning it can occur without the input of external energy. Therefore, for spontaneity, we require $ΔG$ to be negative.
Option A : $(ΔG = +ve, ΔE = +ve)$ is incorrect because a positive $ΔG$ and positive $ΔE$ indicate a non-spontaneous reaction.
Option B : $(ΔG = 0, ΔE = 0)$ is incorrect because a $ΔG$ of zero indicates that the reaction is at equilibrium, not necessarily spontaneous.
Option D : $(ΔG = -ve, ΔE = 0)$ is incorrect because while a negative $ΔG$ indicates spontaneity, the value of $ΔE$ can be non-zero. The cell potential (ΔE$$) is related to $ΔG$ through the equation $ΔG = -nFΔE$, and ΔE can have a non-zero value for spontaneous reactions.
Therefore, the correct statement for spontaneity of a cell is $ΔG = -ve$, indicating a negative Gibbs free energy change.