Q2. In an experiment, ammonia gas is made by heating a mixture of ammonium chloride and calcium hydroxide.

[tex]\[
2 \text{NH}_4\text{Cl} (s) + \text{Ca}(\text{OH})_2 (s) \rightarrow \text{CaCl}_2 (s) + 2 \text{NH}_3 (g) + 2 \text{H}_2\text{O} (l)
\][/tex]

[tex]$10.0 \text{g}$[/tex] of ammonium chloride is added to an excess of calcium hydroxide.

Calculate the maximum volume of ammonia gas that could be formed.

(Relative atomic masses: [tex]$H = 1.00$[/tex], [tex]$N = 14.0$[/tex], [tex]$O = 16.0$[/tex], and [tex]$Ca = 40.0$[/tex]; one mole of any gas occupies [tex]$24 \text{dm}^3$[/tex] at room temperature and pressure)



Answer :

To determine the maximum volume of ammonia gas ([tex]\( NH_3 \)[/tex]) that can be formed from heating ammonium chloride ([tex]\( NH_4Cl \)[/tex]) with excess calcium hydroxide, we need to follow these steps:

1. Calculate the molar mass of ammonium chloride ([tex]\( NH_4Cl \)[/tex]):
Ammonium chloride is composed of:
- Nitrogen (N): 1 atom with atomic mass of 14.0
- Hydrogen (H): 4 atoms with atomic mass of 1.00 each
- Chlorine (Cl): 1 atom with atomic mass of 35.45

The molar mass of [tex]\( NH_4Cl \)[/tex] can be calculated as:
[tex]\[ \text{Molar mass of } NH_4Cl = (14.0) + (4 \times 1.00) + (35.45) = 53.45 \, \text{g/mol} \][/tex]

2. Calculate the moles of [tex]\( NH_4Cl \)[/tex] used:

Given that 10.0 grams of [tex]\( NH_4Cl \)[/tex] is used, we can find the number of moles by:
[tex]\[ \text{Moles of } NH_4Cl = \frac{10.0 \, \text{g}}{53.45 \, \text{g/mol}} \approx 0.187 \, \text{moles} \][/tex]

3. Determine the moles of [tex]\( NH_3 \)[/tex] produced:

According to the balanced chemical equation:
[tex]\[ 2 \, NH_4Cl (s) + Ca(OH)_2 (s) \rightarrow CaCl_2 (s) + 2 \, NH_3 (g) + 2 \, H_2O (l) \][/tex]
The stoichiometry shows that 2 moles of [tex]\( NH_4Cl \)[/tex] produce 2 moles of [tex]\( NH_3 \)[/tex]. This is a 1:1 molar ratio. Therefore, the moles of [tex]\( NH_3 \)[/tex] produced will be equal to the moles of [tex]\( NH_4Cl \)[/tex] used:
[tex]\[ \text{Moles of } NH_3 = 0.187 \, \text{moles} \][/tex]

4. Calculate the volume of [tex]\( NH_3 \)[/tex] gas produced at room temperature and pressure:

At room temperature and pressure (RTP), 1 mole of any gas occupies 24 dm³. Therefore:
[tex]\[ \text{Volume of } NH_3 \text{ gas} = \text{Moles of } NH_3 \times 24 \, \text{dm}^3/\text{mol} \][/tex]
Substituting the value we have:
[tex]\[ \text{Volume of } NH_3 \text{ gas} = 0.187 \, \text{moles} \times 24 \, \text{dm}^3/\text{mol} \approx 4.49 \, \text{dm}^3 \][/tex]

Therefore, the maximum volume of ammonia gas ([tex]\( NH_3 \)[/tex]) that could be formed is [tex]\( 4.49 \, \text{dm}^3 \)[/tex].

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