Question

$Zn\left|\right.Zn^{2 +}\left(\right.C_{1}\left.\right)\left|\right.\left|\right.Zn^{2 +}\left(\right.C_{2}\left.\right)\left|\right.Zn$ . For this cell $\Delta G$ is negative if

• A. $C_{1}=C_{2}$
• B. $C_{1}>C_{2}$
• C. $C_{2}>C_{1}$
• D. None of these

Answer 1

Answer: (C)

$Anode: \, Zn \rightarrow Zn^{+ 2}\left(C_{1}\right)$

Cathode: $\mathrm{Zn}^{+2}\left(\mathrm{C}_2\right) \rightarrow \mathrm{Zn}$

$K_{c}=\frac{\left(Z n^{+ 2}\right) A}{\left(Z n^{+ 2}\right) C}=\left(\frac{C_{1}}{C_{2}}\right)$

$E=E^{o}-\frac{0.0591}{2}log k_{c}$

$\Delta G=-nFE$

$E=E^\circ -\frac{0.0591}{2}log\frac{C_{1}}{C_{2}}=\frac{0.0591}{2}log\frac{C_{2}}{C_{1}}$

to make $\Delta G=-ve$

$\Delta E=+ve$ hence, $C_{2}>C_{1}$