Question

The mass of silver (Molar mass of Ag : 108 gmol^–1 ) displaced by a quantity of electricity which displaces 5600 mL of O₂ at S.T.P. will be _____ g.

Answer 1

Correct Answer: 108

To solve this problem, we need to determine the mass of silver (Ag) displaced when a certain quantity of electricity displaces 5600 mL of O₂ at standard temperature and pressure (STP). 

Firstly, at STP, 1 mole of any gas occupies 22.4 L (22,400 mL). Therefore, the moles of O₂ displaced are:

Moles of O₂ = \(\frac{5600 \,\text{mL}}{22400 \,\text{mL/mol}} = 0.25 \,\text{mol}\)

Now, according to the electrolytic process for the displacement of silver using electricity, we have the following reaction for water electrolysis:

2H₂O → 4H⁺ + O₂ + 4e^-

This indicates that 1 mole of O₂ is produced by 4 faradays of electricity.

Thus, 0.25 moles of O₂ are produced by:

0.25 × 4 = 1 faraday of electricity

The reaction for displacement of silver is:

Ag⁺ + e^- → Ag

This shows that 1 mole of Ag requires 1 faraday of electricity. Therefore, 1 faraday will deposit 1 mole of Ag.

The molar mass of Ag is 108 g/mol. Thus, 1 faraday will deposit:

108 g of Ag

Therefore, the mass of silver displaced by the given quantity of electricity is 108 g.

Answer 2

The equation for the equivalent of Ag is:

$$\text{Eq. of Ag} = \text{Eq. of } O_2$$

Let x grams of silver be displaced.

$$\frac{x}{108} = \frac{5.6}{22.7} \times 4$$

Using the molar volume of gas at STP (22.7 L), we get:

$$x = 106.57 \, \text{g}$$

Thus, the answer is approximately 107 g.

Alternatively, using 22.4 L as the molar volume at STP:

$$\frac{x}{108} = \frac{5.6}{22.4} \times 4$$

which gives $$x = 108 \, \text{g}$$.