Question

If $\Delta \text{G} = \Delta \text{H} - \text{T} \Delta \text{S}$ and $\Delta \text{G} = \Delta \text{H} + \text{T} \left[\frac{\text{d} \left(\Delta \text{G}\right)}{\text{dT}}\right]$ , then variation of EMF of a cell E, with temperature T, is given by

• A. $\frac{\Delta \text{H}}{\text{nF}}$
• B. $\frac{\Delta \text{G}}{\text{nF}}$
• C. $\frac{\Delta \text{S}}{\text{nF}}$
• D. $\frac{- \Delta \text{S}}{\text{nF}}$

Answer 1

Answer: (C)

By comparision we get

$\Delta \text{S} = \frac{- \text{d} \left(\Delta \text{G}\right)}{\text{dT}}$

by substituting $\Delta \text{G} = - \text{nFE}$ and rearranging we get

$\frac{\text{dE}}{\text{dT}} = \frac{\Delta \text{S}}{\text{nF}}$