Chemistry Test Gas Laws 2 — Questions and Answers
Question 1: A gas occupies 4.0 L at 2.0 atm. What volume does it occupy at 0.5 atm (constant temperature)?
- 1.0 L
- 8.0 L
- 16.0 L (Correct answer)
- 2.0 L
Correct answer: 16.0 L
By Boyle's Law, P1V1 = P2V2: (2.0)(4.0) = (0.5)(V2), so V2 = 16.0 L.
Question 2: A gas at 300 K occupies 6.0 L. At what temperature will it occupy 9.0 L at constant pressure?
- 200 K
- 450 K (Correct answer)
- 400 K
- 600 K
Correct answer: 450 K
By Charles's Law, V1/T1 = V2/T2: 6.0/300 = 9.0/T2, giving T2 = 450 K.
Question 3: What does the van der Waals equation correct for compared to the ideal gas law?
- Only molecular volume
- Only intermolecular attractions
- Both molecular volume and intermolecular attractions (Correct answer)
- Temperature dependence of pressure
Correct answer: Both molecular volume and intermolecular attractions
The van der Waals equation adds correction terms for finite molecular volume (b) and intermolecular attractions (a).
Question 4: Which gas law is applied when a sealed rigid container is heated, causing pressure to increase?
- Boyle's Law
- Charles's Law
- Gay-Lussac's Law (Correct answer)
- Avogadro's Law
Correct answer: Gay-Lussac's Law
Gay-Lussac's Law states that at constant volume, pressure is directly proportional to temperature.
Question 5: Using the ideal gas law, how many moles of gas are in a 22.4 L container at STP?
- 0.5 mol
- 1.0 mol (Correct answer)
- 2.0 mol
- 0.25 mol
Correct answer: 1.0 mol
At STP (273.15 K, 1 atm), one mole of ideal gas occupies exactly 22.4 L by definition.
Question 6: A balloon contains 2.0 mol of helium at 1.0 atm. If 2.0 more mol of helium are added at constant T and P, what happens to the volume?
- Stays the same
- Doubles (Correct answer)
- Halves
- Quadruples
Correct answer: Doubles
Avogadro's Law states volume is directly proportional to moles at constant T and P, so doubling moles doubles volume.
Question 7: A mixture of gases has partial pressures: N2 = 0.6 atm, O2 = 0.2 atm, CO2 = 0.1 atm. What is the total pressure?
- 0.6 atm
- 0.8 atm
- 0.9 atm (Correct answer)
- 1.0 atm
Correct answer: 0.9 atm
Dalton's Law: Ptotal = PN2 + PO2 + PCO2 = 0.6 + 0.2 + 0.1 = 0.9 atm.
Chemistry Test Gas Laws 2
A gas occupies 4.0 L at 2.0 atm.
What volume does it occupy at 0.5 atm (constant temperature)?