Q31 / 120 · VITEEE 2007 · Chemistry
How long (in hours) must a current of $5.0$ amperes be maintained to electroplate $60 \mathrm{~g}$ of calcium from molten $\mathrm{CaCl}_{2}$ ?
- A27 hours
- B$8.3$ hours
- C11 hours
- Correct answerD16 hours
Solution
$\begin{array}{l}
\text { Eq. mass of } \mathrm{Ca}^{++}=\frac{\text { Mol.mass }}{2}=\frac{40}{2}=20 \\
\mathrm{Z}=\frac{\text { Eq. mass of water }}{96500}=\frac{20}{96500} \\
\text { Given } \mathrm{w}=60 \mathrm{~g}, \mathrm{i}=5 \mathrm{amp} \\
\mathrm{w}=\text { zit }
\end{array}$
$\begin{array}{l}
\text { or } 60=\frac{20}{96500} \times 5 \times t \\
\therefore t=\frac{96500 \times 60}{20 \times 5}=57900 \sec =16 h
\end{array}$
Hence, the correct answer is option: 'D'.