Question

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

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

Answer 1

Answer: (C)

$0.521$V

Given reactions,

$C{u}^{2+}+2e^{-}\to Cu,E_{cell}=0.337$

$C{u}^{2+}+e^{-}\to C{u}^{+},E_{cell}=0.153$

So for required equation,

$C{u}^{+}+2e^{-}\to Cu$

Here we have to know that cell potential is an intensive property and hence we can't add or subtract it simply.

We have to do calculations according to $\Delta G$

We know,$\Delta G=-nF{E}_{cell}$

So,

$\Delta G_3=E_{C{u}^{2+}/Cu}-E_{C{u}^{2+}/C{u}^{+}}$

$⟹E_{cell}=2\times 0.337-0.153$

$⟹E_{cell}=0.521V$
Option C is correct.