Question

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

• A. $+0.158\text{V}$
• B. $0.182\text{V}$
• C. $-0.182\text{V}$
• D. $-0.158\text{V}$

Answer 1

The correct option is A $+0.158\text{V}$


$\Delta G^0=-nF{E}^0$
$C{u}^{2+}+2e^{-}\to Cu$ .... (1)
$C{u}^{2+}+e^{-}\to C{u}^{+}$ ....(2)
$C{u}^{+}+e^{-}\to Cu$ ....(3)
Adding (2) and (3), we get (1)
$\Delta G_1^0=\Delta G_2^0+\Delta G_3^0$
$\Rightarrow 2\times 0.34=E_2^0+1\times 0.522$
$\Rightarrow E_2^0=0.68-0.522$
$\Rightarrow E_2^0=0.158\text{V}$
Hence option (a) is correct.