Question

The weight of silver (atomic weight $=108$) displaced by a quantity of electricity which displaces 5600 ml of $O_2$ at STP will be:

• A. $5.4g$
• B. $10.8g$
• C. $108.0g$
• D. $54.0g$

Answer 1

Answer: (C)

At STP, 1 mole of oxygen occupies 22400 mL.
Hence, the number of moles of oxygen corresponding to 5600 ml is $n_{O_2}=\frac{5600}{22400}=\frac{1}{4}=\frac{W_{O_2}}{M_{O_2}}$.
1 mole of oxygen produces 4 moles of lectrons and 1 mole of silver requires 1 mole of electrons.

$\frac{W_{Ag}}{M_{Ag}}\times 1=\frac{W_{O_2}}{M_{O_2}}\times 4$

$\frac{W_{Ag}}{M_{Ag}}\times 1=\frac{1}{4}\times 4$

$\frac{W_{Ag}}{108}=\frac{1}{4}\times 4$

$W_{Ag}=108g$

Thus, the weight of silver displaced by a quantity of electricity which displaces 5600 ml of $O_2$ at STP will be 108.0 g.