Question

The standard emf for the given cell reaction, $Zn + Cu ^{2+} \longrightarrow Cu + Zn ^{2+}$ is $1.10\, V$ at $25^{\circ} C$. The emf for the cell reaction, when $0.1\, M\, Cu ^{2+}$ and $0.1\, M\, Zn ^{2+}$ solutions are used at $25^{\circ} C$ is

• A. 1.10 V
• B. -1.10 V
• C. 2.20 V
• D. -2.20 V

Answer 1

Answer: (A)

$E_{\text {cell }} =E_{\text {cell }}^{\circ}-\frac{0.059}{2} \log \frac{\left[ Zn ^{2+}\right]}{\left[ Cu ^{2+}\right]}$
$=1.10-\frac{0.059}{2} \log \frac{0.1}{0.1}$
$=1.10\, V$