Question

Given:
(i) ${Cu}^{2+}+2e^{-}\to Cu,E^0=0.337V$
(ii) ${Cu}^{2+}+e^{-}\to {Cu}^{+},E^0=0.153$
Standard electrode potential, $E^{\circ }$ for the reaction, $Cu+e^{-}\to Cu$, will be (in volts):

Answer 1

Correct Answer: 0.52

Explanation:
We know that, $\mathrm{\Delta }{G}^{\circ }=-nF{E}^{\circ }$
So for the reaction, $C{u}^{2+}+2e^{-}\to Cu$$\mathrm{\Delta }{G}^{\circ }=2\times F\times 0.337\dots (1)$
For the reaction, $C{u}^{+}\to C{u}^{2+}+e^{-}$$\mathrm{\Delta }{G}^{\circ }=1\times F\times 0.153\dots (2)$
So adding both the equations, we get
$C{u}^{+}+e^{-}\to Cu;$
ΔG∘=−0.521 F
$\mathrm{\Delta }{G}^{\circ }=-nFE{}^{\circ }$
$\Rightarrow \mathrm{\Delta }{E}^{\circ }=0.52V$
Hence, the correct answer is $0.52V$.