The standard reduction potentials for the two half-cell reactions are given below :  
${\mathrm{Cd}}^{2+}\left(\mathrm{aq}\right)+2{\mathrm{e}}^{-}\to \mathrm{Cd}\left(\mathrm{s}\right);{\mathrm{E}}^0=-0.40\mathrm{V};$ ${\mathrm{Ag}}^{+}\left(\mathrm{aq}\right)+{\mathrm{e}}^{-}\to \mathrm{Ag}\left(\mathrm{s}\right);{\mathrm{E}}^0=0.80\mathrm{V}$
The standard free energy change for the reaction
$2{\mathrm{Ag}}_{\left(\mathrm{aq}\right)}^{+}+{\mathrm{Cd}}_{\left(\mathrm{s}\right)}\to 2{\mathrm{Ag}}_{\left(\mathrm{s}\right)}+{\mathrm{Cd}}_{\left(\mathrm{aq}\right)}^{2+}$ is given by