Example-1
Example-1
A V dm^{3} flask contains gas A and another flask of 2V dm^{3} contains gas B at the same temperature. If density of gas A is 3.0 g/dm^{3} and that of gas B is 1.5 g/dm^{3} and molecular weight of A = ½ (molecular weight of B), then the ratio of pressure exerted by gases is:
Solution (C)
Using PV = or P =
For gas A, P_{A} = P_{B} =
∴
Example-2
Example-2
A mixture of 50.0 mL of NH_{3} and 60.0 mL of O_{2} gas reacts as:
4NH_{3}(g) + 5O_{2}(g) h 4NO + 6H_{2}O(g).
If all the gaseous are at the same temperature and pressure and the reaction continues until one of the gases is completely consumed, what volume of water vapor is produced?
- 48 mL
- 60.0 mL
- 72 mL
- 75.0 mL
Solution (C)
4NH_{3} + 5O_{2} → 4NO + 6H_{2}O
4 mol 5 mol
50 mL 60 mL
Equal mole contains equal volume under given conditions.
H_{2}O(g) obtained from 50 mL of NH_{3} = 75 mL
H_{2}O(g) obtained from 60 mL of O_{2} = 72 mL
Hence O_{2} is limiting reactant. Hence 72 mL.
Example-3
Example-3
If for two gases of molecular weights M_{A} and M_{B} at temperature T_{A} and T_{B}, T_{A}T_{B} = T_{B}M_{A}, then which property has the same magnitude for both the gases?
- Density
- Pressure
- KE per mole
- u_{rms}
Solution (D)
- Density of a gas
- Pressure of the gases would be equal if their densities are equal, otherwise not.
- KE per mol
- u_{rms} of A = u_{rms} of B
Example-4
Example-4
The intercept on the y-axis and slope of curve plotted between P/T and T. For an ideal gas having 10 mol in a closed rigid container of volume 8.21 L, find P (pressure in atm) and T (temperature in K). (log_{10} 2 = 0.30)
- 0.01, 0
- 0.1, 1
- 0.1, 0
- 10, 1
Solution (B)
Intercept on the y-axis = log_{10}
curve
Intercept = =
Slope = 0
Example-5
Example-5
What percent of a sample of nitrogen must be allowed to escape if its temperature, pressure, and volume are to be changed from 220°C, 3 atm, and 1.65 L to 110°C, 0.7 atm, and 1 L, respectively?
- 41.4%
- 8.18%
- 4.14%
- 81.9%
Solution (D)
Fraction remaining =
= 0.182
Fraction escaped = 1 – 0.182 = 0.818
Percentage escaped = 81.8%