Question

The EMF of the cell,
$Mg | Mg^{2+} (0.0IM) || Sn^{2+} (0.1 M) | Sn$ at $298K$ is
$\left(E^{\circ}_{Mg^{2+}/Mg} = -2.34V, E^{\circ }_{Sn^{2+}/Sn} = -0.14V\right)$

• A. 2.17 V
• B. 2.23 V
• C. 2.51 V
• D. 2.45 V

Answer 1

Answer: (B)

The cell reaction is
$M g+S n^{2+} \rightarrow M g^{2+}+S n$
$E_{\text {cell }}=E_{\text {cell }}^{\circ}-\frac{0.0591}{2} \log \frac{\left[ Mg ^{2+}\right]}{\left[ Sn ^{2+}\right]}$
$=(2.34-0.14)-\frac{0.0591}{2} \log \frac{10^{-2}}{10^{-1}}=2.23 V$