A hypothetical electrochemical cell is show below $\stackrel{\Theta}{\mathrm{A}}\left|\mathrm{A}^{+}(x…

A hypothetical electrochemical cell is show below $\stackrel{\Theta}{\mathrm{A}}\left|\mathrm{A}^{+}(x \mathrm{M}) \| \mathrm{B}^{+}(y \mathrm{M})\right| \stackrel{\oplus}{\mathrm{B}}$ The emf measured is $+0.20 \mathrm{~V}$. The cell reaction is:
  1. $\mathrm{A}+\mathrm{B}^{+} \rightarrow \mathrm{A}^{+}+\mathrm{B}$
  2. $\mathrm{A}^{+}+\mathrm{B} \rightarrow \mathrm{A}+\mathrm{B}^{+}$
  3. $\mathrm{A}^{+}+e^{-} \rightarrow \mathrm{A}$; $\mathrm{B}^{+}+e^{-} \rightarrow \mathrm{B}$
  4. the cell reaction cannot be predicted

Solution

$\mathrm{A} / \mathrm{A}^{+}(x \mathrm{M}) \| \mathrm{B}^{+}(y \mathrm{M}) / \mathrm{B}$ $\mathrm{E}_{\text {cell }}=+0.20 \mathrm{~V} \therefore \Delta \mathrm{G}=-v e$ Therefore given cell reaction is spontaneous At Anode $\quad \mathrm{A} \rightarrow \mathrm{A}^{+}+e^{-}$ \begin{array}{ll} At Cathode & \mathrm{B}^{+}+e^{-} \rightarrow \mathrm{B} \\ \hline Cell reaction & \mathrm{A}+\mathrm{B}^{+} \rightarrow \mathrm{A}^{+}+\mathrm{B} \end{array}

Asked in: NEET 2006

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