Question

Given that the standard potentials ($E^0$) of $C{u}^{2+}/Cu\text{and}C{u}^{+}/Cu$ are $0.34V$ and $0.522V$ respectively, the $E^0$ of $C{u}^{2+}/C{u}^{+}$ is-
(JEE MAIN 2020)

• A. $-0.182V$
• B. $+0.158V$
• C. $0.182V$
• D. $-0.158V$

Answer 1

The correct option is B $+0.158V$


$\Delta G^0=-nF{E}^0$
$C{u}^{2+}+2e^{-}\to Cu.....\left(3\right)$
$C{u}^{2+}+e^{-}\to C{u}^{+}.....\left(1\right)$
$C{u}^{+}+e^{-}\to Cu......\left(2\right)$
Adding equation (1) and (2), we get (3)
$\Delta G_3^0=\Delta G_1^0+\Delta G_2^0$

$2\times 0.34=E_1^0+1\times 0.522$

$E_1^0=0.68-0.522$

$E_1^0=0.158V$

Hence, option (a) is correct.