The time required to coat a metal surface of $80 {\mathrm{cm}}^2$ with 0.005 mm thick layer of silver ( density $10.5 \mathrm{g} {\mathrm{cm}}^{-3}$) with the passage of 3 A current through a silver nitrate solution is

$$\begin{gathered} t=\frac{mF\left|v_{\mathrm{e}}\right|}{IM}=\frac{\left(V\rho \right)F\left|v_{\mathrm{e}}\right|}{IM} \\ =\frac{(80\times 0.005\times 10.5 \mathrm{g})\left(96500 \mathrm{C} {\mathrm{mol}}^{-1}\right)\left(1\right)}{\left(3\mathrm{A}\right)\left(108 \mathrm{g} {\mathrm{mol}}^{-1}\right)}=125.0 \mathrm{s} \end{gathered}$$

The time required to coat a metal surface of $80 {\mathrm{cm}}^2$ with 0.005 mm thick layer of silver ( density $10.5 \mathrm{g} {\mathrm{cm}}^{-3}$) with the passage of 3 A current through a silver nitrate solution is 125 s.