Question

Standard cell voltage for the cell
$Pb|P{b}^{2+}||S{n}^{2+}|Sn$ is $-0.01V.$ If the cell is to exhibit $E_{\text{cell}}=0$, the value of $[S{n}^{2+}]/[P{b}^{2+}]$ should be antilog of-

• A. +0.3
• B. 0.5
• C. 1.5
• D. -0.5

Answer 1

Answer: (A)

Apply Nernst equation to the reaction
$Pb+S{n}^{2+}\to P{b}^{2+}+Sn$
or $E^{\circ }+\frac{0.059}{2}\log \frac{\left[S{n}^{2+}\right]}{\left[P{b}^{2+}\right]}=E_{\text{cell}}$
or$\log \frac{\left[S{n}^{2+}\right]}{\left[P{b}^{2+}\right]}=\frac{0.01\times 2}{0.059}=0.3$
$\left(\because E_{\text{cell}}=0\right)$
or $\frac{\left[S{n}^{2+}\right]}{\left[P{b}^{2+}\right]}=$ antilog $\left(0.3\right)$