Statement I: An electrochemical cell can be set up only when the redox reaction is spontaneous. Stat — Electrochemistry Chemistry Question

💡 Solution & Explanation

\textbf{Assertion (I):} An electrochemical cell can be set up only when the redox reaction is spontaneous. \textbf{Reason (II):} A reaction is spontaneous if the free energy change at constant $T$ and $P$ is negative ($\Delta G < 0$). \textbf{Analysis:} \textbf{Statement I:} A galvanic (electrochemical) cell converts chemical energy to electrical energy. This conversion is only possible when the underlying redox reaction is thermodynamically spontaneous. A non-spontaneous reaction would require external energy input (electrolytic cell). ✓ \textbf{Correct.} \textbf{Statement II:} The criterion for spontaneity at constant temperature and pressure is $\Delta G < 0$. ✓ \textbf{Correct.} \textbf{Does II explain I?} The link is: $\Delta G = -nFE^\circ_{\text{cell}}$. If the cell reaction is spontaneous, $\Delta G < 0$, which means $E^\circ_{\text{cell}} > 0$, and the cell produces a positive EMF — confirming it can function as a galvanic cell. Statement II provides the thermodynamic criterion that directly explains why spontaneity (a necessary condition) is required for a galvanic cell. \textbf{Answer: A} (Both correct, Statement II correctly explains Statement I)