Question

Silver is monovalent and has an atomic mass of 108. Copper is divalent and has an atomic mass of 63.6. The same electric current is passed, for the same length of time through a silver coulometer and a copper coulometer. If 27.0 g of silver is deposited, then the corresponding amount of copper deposited is

• A. 63.60 g
• B. 31.80 g
• C. 15.90 g
• D. 7.95 g

Answer 1

The correct option is D 7.95 g

According to the Faraday's second law,

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

Given, the mass of Ag deposited $=27g$.

$Eq.wt.=$$\frac{Atomicmass}{valency}$

Thus,

$Eq.wt.ofAg=$$\frac{108}{1}$$=108$ (Valency of Ag = 1)

$Eq.wt.ofCu=$$\frac{63.6}{2}$ $=31.8$ (Valency of Cu = 2)

$\therefore \text{Mass of Cu deposited = Mass of Ag deposited}$$\times \frac{Eq.wt.ofCu}{Eq.wt.ofAg}$

$\text{Mass of Cu deposited}=27\times$$\frac{31.8}{108}$$=7.95g$

Hence, option D is correct.