Question

An electric current is passed through silver nitrate solution using silver electrodes. $15.28$g of silver was found to be deposited on cathode. What will be the weight of copper deposited on cathode if same amount of electricity is passed through copper sulphate solution using copper electrodes?

• A. $2.7$g
• B. $4.5$g
• C. $27$g
• D. $5.4$g

Answer 1

Answer: (B)

$4.5$g

Faraday's second law of electrolysis states that, when the same quantity of electricity is passed through several electrolytes, the mass of the substances deposited are proportional to their respective chemical equivalent or equivalent weight.

We know that,

Equivalent weight of Ag =$\frac{108}{1}=108$

Equivalent weight of Cu =$\frac{63.5}{2}=31.75$

Now as per Faraday's second law,

$\frac{Eq.wt.ofAg}{Eq.wt.ofCu}$=$\frac{MassofAgdeposited}{MassofCudeposited}$

$⟹\frac{108}{31.75}=\frac{15.28}{W}⟹W=\frac{15.28\times 31.75}{108}=4.49g$