The cell potential (E_cell) of a reaction is related as $\mathrm{\Delta G}=-{\mathrm{nFE}}_{\text{cell }},\text{ where }\mathrm{\Delta G}$ represents max. useful electrical work n = no. of moles of electrons exchanged during the reaction

for reversible cell reaction $\mathrm{d}\left(\mathrm{\Delta G}\right)=\left({\mathrm{\Delta }}_{\mathrm{r}}\mathrm{V}\right)\mathrm{dp}-\left({\mathrm{\Delta }}_{\mathrm{r}}\mathrm{S}\right)\cdot \mathrm{dT}$

at constant pressure $\mathrm{d}\left(\mathrm{\Delta G}\right)=-\left({\mathrm{\Delta }}_{\mathrm{r}}\mathrm{S}\right)\cdot \mathrm{dT}$ 

$\because \text{ At constant pressure }\mathrm{\Delta G}=\mathrm{\Delta H}-\mathrm{T}\cdot \mathrm{\Delta S}$            . . . . (1)

$\therefore \mathrm{\Delta G}=\mathrm{\Delta H}+\mathrm{T}{\left(\frac{\mathrm{d}\left(\mathrm{\Delta G}\right)}{\mathrm{dT}}\right)}_{\mathrm{p}}$                                      . . . . .(2)

${\left(\frac{{\mathrm{dE}}_{\text{cell }}}{\mathrm{dT}}\right)}_{\mathrm{p}}\text{ is known as temperature coefficient of the e.m.f of the cell }$