Chemistry Test Gas Laws 3 — Questions and Answers
Question 1: A gas at 1.5 atm and 10.0 L is compressed to 5.0 L at constant temperature. What is the new pressure?
- 0.75 atm
- 1.5 atm
- 3.0 atm (Correct answer)
- 6.0 atm
Correct answer: 3.0 atm
Boyle's Law: P2 = P1V1/V2 = (1.5 × 10.0)/5.0 = 3.0 atm.
Question 2: Which of the following best describes an ideal gas?
- Molecules with strong attractions and large volume
- Point masses with no intermolecular forces (Correct answer)
- Molecules that condense easily at low temperatures
- Gases with high molecular weight
Correct answer: Point masses with no intermolecular forces
An ideal gas is modeled as point masses (negligible volume) with no intermolecular forces.
Question 3: At constant temperature and pressure, which gas sample contains the most molecules?
- 1.0 L of H2
- 1.0 L of O2
- 1.0 L of N2
- All samples contain the same number (Correct answer)
Correct answer: All samples contain the same number
Avogadro's Law states equal volumes of gases at the same T and P contain equal numbers of molecules.
Question 4: A gas exerts 2.0 atm in a 3.0 L container. If the container is expanded to 6.0 L at constant temperature, what is the new pressure?
- 4.0 atm
- 1.0 atm (Correct answer)
- 3.0 atm
- 0.5 atm
Correct answer: 1.0 atm
Boyle's Law: P2 = (2.0 × 3.0)/6.0 = 1.0 atm.
Question 5: What happens to the average kinetic energy of gas molecules when temperature increases?
- Decreases
- Stays the same
- Increases (Correct answer)
- First increases, then decreases
Correct answer: Increases
Average kinetic energy is directly proportional to absolute temperature: KE = (3/2)kT.
Question 6: A gas at 1.0 atm and 546 K is cooled to 273 K. What is the new pressure at constant volume?
- 2.0 atm
- 1.0 atm
- 0.5 atm (Correct answer)
- 4.0 atm
Correct answer: 0.5 atm
Gay-Lussac's Law: P2 = P1T2/T1 = (1.0 × 273)/546 = 0.5 atm.
Question 7: Which unit must temperature be expressed in when using the gas laws?
- Celsius
- Fahrenheit
- Kelvin (Correct answer)
- Rankine
Correct answer: Kelvin
All gas law calculations require absolute temperature in Kelvin to avoid division by zero or negative values.
Chemistry Test Gas Laws 3
A gas at 1.5 atm and 10.0 L is compressed to 5.0 L at constant temperature.
What is the new pressure?