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QJEEM24Ch5248: JEE Main 2024 Chemistry - Class 12 JEEM24Ch5248 Solution: The mass of silver (Molar mass of ) displaced by a quantity of…

The mass of silver (Molar mass of Ag:108 gmol−1\mathrm{Ag}: 108 \mathrm{~gmol}^{-1} ) displaced by a quantity of electricity which displaces 5600 mL5600 \mathrm{~mL} of O2\mathrm{O}_2 at S.T.P. will be ______ g.

Step-by-Step Verified Solution

First, we need to determine the amount of O2\mathrm{O}_2 (oxygen gas) in moles that is displaced by the quantity of electricity mentioned. To do this, we'll use the molar volume of a gas at Standard Temperature and Pressure (S.T.P.), which is approximately 22.4 L/mol22.4 \mathrm{~L/mol} (or 22400 mL/mol22400 \mathrm{~mL/mol} ).

The volume of O2\mathrm{O}_2 is given as 5600 mL5600 \mathrm{~mL} . Now, we convert this volume to moles:

moles of O2=volume of O2molar volume=5600 mL22400 mL/mol=0.25 mol\text{moles of } \mathrm{O}_2 = \frac{\text{volume of } \mathrm{O}_2}{\text{molar volume}} = \frac{5600 \mathrm{~mL}}{22400 \mathrm{~mL/mol}} = 0.25 \mathrm{~mol}

Next, we'll use Faraday's laws of electrolysis to relate the moles of O2\mathrm{O}_2 to the moles of silver being displaced. In electrolysis, silver is deposited at the cathode according to the following half-reaction:

Ag++e−→Ag\mathrm{Ag}^+ + e^- \rightarrow \mathrm{Ag}

This tells us that for each mole of Ag+\mathrm{Ag}^+ ions, only 1 mole of electrons is required to reduce it to silver metal Ag\mathrm{Ag} . However, the liberation of oxygen gas involves the following half-reaction:

2H2O(l)→O2(g)+4H+(aq)+4e−2\mathrm{H_2O} (l) \rightarrow \mathrm{O}_2 (g) + 4H^+ (aq) + 4e^-

From this reaction, we can see that 1 mole of O2\mathrm{O}_2 gas requires 4 moles of electrons to be produced. Therefore, the number of moles of electrons associated with the 0.25 mol0.25 \mathrm{~mol} of O2\mathrm{O}_2 will be:

moles of electrons for O2=0.25 mol×4=1 mol\text{moles of electrons for } \mathrm{O}_2 = 0.25 \mathrm{~mol} \times 4 = 1 \mathrm{~mol}

Now, since it takes 1 mole of electrons to reduce 1 mole of Ag+\mathrm{Ag}^+ . The moles of electrons required is equal to the moles of Ag\mathrm{Ag} produced. Hence, we have 1 mole of Ag\mathrm{Ag} being deposited.

Finally, to calculate the mass of this silver, we use the molar mass of silver:

Mass of Ag=(moles of Ag)×(Molar mass of Ag)=1 mol×108 gmol−1=108 g\text{Mass of Ag} = (\text{moles of Ag}) \times (\text{Molar mass of Ag}) = 1 \mathrm{~mol} \times 108 \mathrm{~gmol}^{-1} = 108 \mathrm{~g}

So, the mass of silver displaced by the quantity of electricity that displaces 5600 mL of O2\mathrm{O}_2 at S.T.P. will be 108 g108 \mathrm{~g} .

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