How long a current of 3 amperes has to be passed through a solution of $\mathrm{AgNO}_{3}$ to coat a metal…

How long a current of 3 amperes has to be passed through a solution of $\mathrm{AgNO}_{3}$ to coat a metal surface of $80 \mathrm{~cm}^{2}$ and $0.005 \mathrm{~mm}$ thick layer. Density of $\mathrm{Ag}$ is $10.5 \mathrm{~g} \mathrm{~cm}^{-3}$
  1. $125.1$ seconds
  2. $12.5$ seconds
  3. $155.2$ seconds
  4. 200 seconds

Solution

Volume $=$ Area $\times$ thickness
Mass $=$ Volume $\times$ density
$\therefore$ Mass of $\mathrm{Ag}$ to be deposited
$=\frac{80 \times 0.005}{10} \times 10.5=0.42 \mathrm{~g}$
Amount deposited $=\frac{i \times t \times E . w t}{96500}$
$\therefore 0.42=\frac{108 \times 3 \times \mathrm{t}}{98500} \therefore \mathrm{t}=125.1$ seconds

Asked in: JEE-TOPICTESTS-CHEMISTRY

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