Question

Determine the standard emf of the cell and standard free energy change of the cell reaction.
$Zn{/Zn}^{2+}\parallel {Ni}^{2+}/N$
$E^o$ ${Zn}^{2+}/Zn=-0.76V$
$E^o$ ${Ni}^{2+}/Ni=-0.25V$

Answer 1

$Zn{,Zn}^{2+}\parallel {Ni}^{2+},Ni$
$E_{cell}^{\circ }=E_R^{\circ }-E_L^{\circ }=-0.25-(-0.76)=+0.51V$
$E_{cell}$ is a positive $\therefore \Delta G^{\circ }=-$ve
$\therefore \Delta G^{\circ }=-nF{E}_{cell}^{\circ }$
$n=2$ electrons
$\therefore \Delta G^{\circ }=-2\times 96495\times 0.51=-97460joules=-97.46kJ$