How long must a current of 5 A be maintained to electroplate 60 g Ca from molten $\mathrm{CaCl}_{2}$

Question

How long must a current of 5 A be maintained to electroplate 60 g Ca from molten $\mathrm{CaCl}_{2}$ ?\

Professor PC Thomas Classes · Answer

$\mathrm{Ca}^{2+}+2 \overline{\mathrm{e}} ightarrow \mathrm{Ca}$ 1 mole ie 40 g Ca is deposited by $2 \mathrm{~F}=2 	imes 96500 \mathrm{C}$\ $	herefore 60 \mathrm{~g}$ is deposited by $\frac{2 	imes 96500}{40} 	imes 60=3 	imes 96500 \mathrm{C}$\ $\mathrm{Q}=\mathrm{I} 	imes \mathrm{t}$\ $\mathrm{t}=\frac{\mathrm{Q}}{5}=\frac{3 	imes 96500}{5}=57900 \mathrm{~s}=\frac{57900}{60 	imes 60}=16 \mathrm{hr}$\