The standard reduction potentials of $$C{u^{2 + }}\left| {Cu\,{\text{and}}\,C{u^{2 + }}} \right|C{u^ + }$$     are $$0.337 V$$  and $$0.153$$  respectively. The standard electrode potential of $$C{u^ + }\left| {Cu\,} \right.$$  half cell is

Solution :
We have

Half-cell	Half-cell reaction	$$\Delta {G^ \circ } = - nF{E^ \circ }$$
$$C{u^{2 + }}\left| {Cu} \right.$$	$$C{u^{2 + }} + 2{e^ - } = Cu$$	$$\Delta G_1^ \circ = - 2FE_{C{u^{2 + }}\left| {Cu} \right.}^ \circ $$
$$C{u^{2 + }}{\left| {Cu} \right.^ + }$$	$$C{u^{2 + }} + {e^ - } = C{u^ + }$$	$$\Delta G_2^ \circ = - FE_{C{u^{2 + }}{{\left| {Cu} \right.}^ + }}^ \circ $$
$$C{u^ + }\left| {Cu} \right.$$	$$C{u^ + } + {e^ - } = Cu$$	$$\Delta G_3^ \circ = - FE_{C{u^ + }\left| {Cu} \right.}^ \circ $$

From the half-cell reactions, it follows that
$$\eqalign{ & \Delta G_3^ \circ = \Delta G_1^ \circ - \Delta G_2^ \circ \cr & i.e., \cr & - F{E^ \circ }_{C{u^ + }\left| {Cu} \right.} = - 2F{E^ \circ }_{C{u^{2 + }}\left| {Cu} \right.} - \left( { - F{E^ \circ }_{C{u^{2 + }}\left| {C{u^ + }} \right.}} \right) \cr & or\,\,{E^ \circ }_{C{u^ + }\left| {Cu} \right.} = 2{E^ \circ }_{C{u^{2 + }}\left| {Cu} \right.} - {E^ \circ }_{C{u^{2 + }}\left| {C{u^ + }} \right.} \cr & = 2\left( {0.337V} \right) - 0.153V = 0.521V \cr} $$