$\text{ Calculate free energy change for the reaction }\frac{1}{2}\mathrm{Cu}\left(\mathrm{s}\right)+\frac{1}{2}{\mathrm{Cl}}_2\left(\mathrm{g}\right)\rightleftharpoons \frac{1}{2}{\mathrm{Cu}}^{2+}+{\mathrm{Cl}}^{-}\text{taking place at }$

$25°\mathrm{C}$ in a cell whose standard e.m.f. is $1.02$ volts.