Consider the redox reaction, $2{{\mathrm{A}}^{+3}}_{\left(\mathrm{aq}\right)}+2{{\mathrm{B}}^{-}}_{\left(\mathrm{aq}\right)}\to 2{{\mathrm{A}}^{+2}}_{\left(\mathrm{aq}\right)}+{\mathrm{B}}_{2\left(\mathrm{aq}\right)}; {\mathrm{E}}_{\mathrm{cell}}^0=0.3\mathrm{V}$.. Standard Gibb’s energy  $\left({\mathrm{\Delta }}^0\mathrm{G}\right)$ of the reaction will be

$\begin{array}{l}\left[{\mathrm{A}}^{+3}+{\mathrm{e}}^{-}\to {\text{\hspace{0.17em}A}}^{+2}\right]\times 2\\ \left[{\mathrm{B}}^{-}\to \frac{1}{2}{\text{B}}_2+{\mathrm{e}}^{-}\right]\times 2\\ 2{\mathrm{A}}^{+3}+2{\mathrm{B}}^{-}\to 2{\mathrm{A}}^{+2}+{\mathrm{B}}_2\\ \mathrm{n}= 2\\ {\mathrm{\Delta G}}^0=-{\mathrm{nFE}}^0\\ =-2\left(96500\right)\left(0.3\right)\mathrm{J}\\ =-2\left(96.5\right)\left(0.3\right)\mathrm{kJ}\\ =-57.9\mathrm{kJ}\end{array}$