Given : (i) $\mathrm{Cu}^{2+}+2 \mathrm{e}^{-} \rightarrow \mathrm{Cu}_{,} \mathrm{E}^{\circ}=0.337…

Given : (i) $\mathrm{Cu}^{2+}+2 \mathrm{e}^{-} \rightarrow \mathrm{Cu}_{,} \mathrm{E}^{\circ}=0.337 \mathrm{~V}$ (i) $\mathrm{Cu}^{2+}+\mathrm{e}^{-} \rightarrow \mathrm{Cu}^{+}, \mathrm{E}^{\circ}=0.153 \mathrm{~V}$ Electrode potential $\mathrm{E}^{\circ}$ for the reaction, $\mathrm{Cu}^{+}+\mathrm{e}^{-} \rightarrow \mathrm{Cu}$, will be :
  1. $0.38 \mathrm{~V}$
  2. $0.52 \mathrm{~V}$
  3. $0.90 \mathrm{~V}$
  4. $0.30 \mathrm{~V}$

Solution

$\begin{aligned} & \mathrm{Cu}^{2+}+2 \mathrm{e}^{-} \rightarrow \mathrm{Cu} \\ & \mathrm{E}^{\circ}=0.337 \mathrm{~V} \\ & \Delta \mathrm{G}=-\mathrm{nFE}_{\text {cell }}^0 \\ & \quad=-2 \times \mathrm{F} \times 0.337 \\ & \quad=-0.674 \\ & \mathrm{Cu}^{2+} \rightarrow \mathrm{Cu}^{2+}+\mathrm{e}^{-} \\ & \mathrm{E}^{\circ}=-0.153 \mathrm{~V} \\ & \Delta \mathrm{G}=+1 \times \mathrm{F} \times 0.153 \end{aligned}$ Final $\begin{aligned} & \mathrm{Cu}^{+}+\mathrm{e}^{-} \rightarrow \mathrm{Cu} \\ & \Delta \mathrm{G}=-0.52 \mathrm{~V} \\ & \Delta \mathrm{G}=-\mathrm{nFE}_{\text {cell }}^{\circ} \\ & \mathrm{E}_{\text {cell }}^{\circ}=0.52 \mathrm{~V} \end{aligned}$

Asked in: NEET 2009 (Mains)

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