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Ideal gas law test with answers for AP Physics 2 (free PDF download)

Quick answer: An ideal gas is a collection of tiny, randomly moving particles whose average kinetic energy is proportional to the kelvin temperature. This AP Physics 2 test on ideal gas law has 8 questions worth 20 marks, to do in 45 minutes: kinetic model, particles in a tank and temperature and speed. The mark scheme is on a separate page; free printable PDF.

Ideal gas law test with answers for AP Physics 2 (free PDF download)

This test covers kinetic theory, the ideal gas law and conduction for AP Physics 2. Show all working with units, use T in kelvin and take R = 8.31 J/(mol·K), k_B = 1.38 × 10⁻²³ J/K and N_A = 6.02 × 10²³ mol⁻¹. Some parts ask for a short explanation in complete sentences.

Level: AP Physics 2 (algebra-based) · Curriculum: AP P2 Unit 9

Time: 45 minutes · 8 questions · Total: 20 marks · Calculator allowed

Question 1 Kinetic model (2 marks)

  1. State two assumptions of the ideal gas model. (1 mark)
  2. Explain how particle collisions produce the pressure on a wall. (1 mark)

Question 2 Particles in a tank (3 marks)

A 4.0 L tank holds an ideal gas at 1.5 × 10⁵ Pa and 300 K.
  1. Calculate the amount of gas in moles. (2 marks)
  2. Calculate the number of molecules. (1 mark)

Question 3 Temperature and speed (2 marks)

A gas is heated from 27 °C to 327 °C.
  1. Calculate the ratio of the new average kinetic energy to the old. (1 mark)
  2. Calculate the ratio of the new vrms to the old. (1 mark)

Question 4 A pressure graph (3 marks)

Graph of pressure in kilopascals against temperature in kelvin for a sealed gas, a straight line through the originT (K)p (kPa)1002003004004080120160(250, 80)(400, 128)
Pressure of a fixed amount of gas in a rigid vessel.
A fixed amount of gas in a rigid 5.0 L vessel gives the graph.
  1. Explain why the line passes through the origin. (1 mark)
  2. Calculate the gradient in Pa/K. (1 mark)
  3. Use the gradient to find the amount of gas. (1 mark)

Question 5 A cool box lid (3 marks)

A cool box with a thick foam lid, warm air at 30 degrees Celsius above and 4 degrees Celsius insidefoam lid, 4.0 cm4 °C inside30 °C outside
Heat leaks mostly through the lid.
The foam lid has k = 0.033 W/(m·K), area 0.30 m² and thickness 4.0 cm. The inside is at 4 °C and the outside at 30 °C.
  1. Calculate the heat flow rate through the lid. (2 marks)
  2. State the effect on the rate of doubling the lid thickness. (1 mark)

Question 6 Metal and wood (3 marks)

Two door handles, one of steel and one of wood, are both at 15 °C. Your hand is at 33 °C.
  1. Explain why the steel handle feels colder. (2 marks)
  2. State which material has the larger thermal conductivity. (1 mark)

Question 7 Faulty reasoning (2 marks)

A student states that when a gas is heated from 20 °C to 40 °C its vrms doubles because 40 is twice 20.
  1. Explain the error. (1 mark)
  2. Calculate the true ratio of the speeds. (1 mark)

Question 8 Compressing air (2 marks)

A sealed syringe of air is slowly compressed to half its volume. The temperature stays constant.
  1. State the new pressure in terms of the old. (1 mark)
  2. Explain this result in terms of collisions with the walls. (1 mark)

See the ideal gas law test answers and mark scheme

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