Question

The standard reduction potentials for $Cu ^{2+} / Cu$ and $Cu ^{2+} / Cu ^{+}$are $0.337$ and $0.153 \,V$ respectively. The standard electrode potential of $Cu ^{+} / Cu$ half-cell is

• A. 0.184V
• B. 0.827V
• C. 0.521V
• D. 0.490V

Answer 1

Answer: (D)

$\Delta G=-n F E^{\circ}$
For, $Cu ^{2+}+2 e^{-} \longrightarrow Cu ; \Delta G_{1}^{\circ}=-2 F(0.337) \ldots$ (i)
$Cu ^{2+}+e^{-} \longrightarrow Cu ^{+} ; \Delta G_{2}^{\circ}=-F(0.153) \ldots$ (ii)
Subtracting (ii) from (i)
$Cu ^{+}+e^{-} \longrightarrow Cu$
$\Delta G^{\circ}=-0.674 F+0.153 F $
$ -n F E^{\circ}=-0.521 F $
$ \because $ For (III) $n=1, $
$\therefore E^{\circ}=0.521 V$