Calculate the volume of each gas sample at STP.

(a) [tex]73.9 \, \text{g} \, N_2[/tex]
(b) [tex]42.9 \, \text{g} \, O_2[/tex]
(c) [tex]148 \, \text{g} \, NO_2[/tex]
(d) [tex]245 \, \text{mg} \, CO_2[/tex]



Answer :

To calculate the volume of each gas sample at Standard Temperature and Pressure (STP), we use the molar volume concept. The molar volume of a gas at STP is 22.414 liters per mole. Here is the detailed solution for each gas sample:

### (a) [tex]\(73.9 \, \text{g} \, \text{N}_2\)[/tex]

1. Given data:
- Mass of [tex]\( \text{N}_2 \)[/tex]: [tex]\(73.9 \, \text{g}\)[/tex]
- Molar mass of [tex]\( \text{N}_2 \)[/tex]: [tex]\(28.02 \, \text{g/mol}\)[/tex]

2. Calculate the number of moles:
[tex]\[ \text{Moles of } \text{N}_2 = \frac{73.9 \, \text{g}}{28.02 \, \text{g/mol}} \approx 2.638 \, \text{moles} \][/tex]

3. Calculate the volume at STP:
[tex]\[ \text{Volume of } \text{N}_2 = 2.638 \, \text{moles} \times 22.414 \, \text{L/mol} \approx 59.115 \, \text{L} \][/tex]

### (b) [tex]\(42.9 \, \text{g} \, \text{O}_2\)[/tex]

1. Given data:
- Mass of [tex]\( \text{O}_2 \)[/tex]: [tex]\(42.9 \, \text{g}\)[/tex]
- Molar mass of [tex]\( \text{O}_2 \)[/tex]: [tex]\(32.00 \, \text{g/mol}\)[/tex]

2. Calculate the number of moles:
[tex]\[ \text{Moles of } \text{O}_2 = \frac{42.9 \, \text{g}}{32.00 \, \text{g/mol}} \approx 1.341 \, \text{moles} \][/tex]

3. Calculate the volume at STP:
[tex]\[ \text{Volume of } \text{O}_2 = 1.341 \, \text{moles} \times 22.414 \, \text{L/mol} \approx 30.049 \, \text{L} \][/tex]

### (c) [tex]\(148 \, \text{g} \, \text{NO}_2\)[/tex]

1. Given data:
- Mass of [tex]\( \text{NO}_2 \)[/tex]: [tex]\(148 \, \text{g}\)[/tex]
- Molar mass of [tex]\( \text{NO}_2 \)[/tex]: [tex]\(46.01 \, \text{g/mol}\)[/tex]

2. Calculate the number of moles:
[tex]\[ \text{Moles of } \text{NO}_2 = \frac{148 \, \text{g}}{46.01 \, \text{g/mol}} \approx 3.216 \, \text{moles} \][/tex]

3. Calculate the volume at STP:
[tex]\[ \text{Volume of } \text{NO}_2 = 3.216 \, \text{moles} \times 22.414 \, \text{L/mol} \approx 72.099 \, \text{L} \][/tex]

### (d) [tex]\(245 \, \text{mg} \, \text{CO}_2\)[/tex]

1. Given data:
- Mass of [tex]\( \text{CO}_2 \)[/tex]: [tex]\(245 \, \text{mg}\)[/tex]
- Convert mass to grams: [tex]\(245 \, \text{mg} = 0.245 \, \text{g}\)[/tex]
- Molar mass of [tex]\( \text{CO}_2 \)[/tex]: [tex]\(44.01 \, \text{g/mol}\)[/tex]

2. Calculate the number of moles:
[tex]\[ \text{Moles of } \text{CO}_2 = \frac{0.245 \, \text{g}}{44.01 \, \text{g/mol}} \approx 0.00557 \, \text{moles} \][/tex]

3. Calculate the volume at STP:
[tex]\[ \text{Volume of } \text{CO}_2 = 0.00557 \, \text{moles} \times 22.414 \, \text{L/mol} \approx 0.125 \, \text{L} \][/tex]

### Summary of Volumes:
- Volume of [tex]\( \text{N}_2 \)[/tex]: [tex]\(59.115 \, \text{L}\)[/tex]
- Volume of [tex]\( \text{O}_2 \)[/tex]: [tex]\(30.049 \, \text{L}\)[/tex]
- Volume of [tex]\( \text{NO}_2 \)[/tex]: [tex]\(72.099 \, \text{L}\)[/tex]
- Volume of [tex]\( \text{CO}_2 \)[/tex]: [tex]\(0.125 \, \text{L}\)[/tex]

These are the volumes of the respective gas samples at STP.