Question

The $\Delta G^\circ$ for the reaction, $\text{Cd}^{2+}(aq) + \text{Zn}(s) \rightarrow \text{Zn}^{2+}(aq) + \text{Cd}(s)$ is: (Given $E_{\text{Cd}^{2+}/\text{Cd}}^\circ = -403\text{ V}$, $E_{\text{Zn}^{2+}/\text{Zn}}^\circ = -763\text{ V}$)}

• A. $-44.5\text{ kJ}$
• B. $-50\text{ kJ}$
• C. $-72.2\text{ kJ}$
• D. $-69.5\text{ kJ}$

Hint:

A spontaneous redox process always has a positive cell potential ($E_{\text{cell}}^\circ > 0$) and a corresponding negative free energy change ($\Delta G^\circ < 0$). Calculating $0.763 - 0.403 = 0.36\text{ V}$ quickly leads to $-2 \times 96500 \times 0.36 \approx -69.5\text{ kJ}$.

Answer 1

The Correct Option is D