AQA GCSE PHYSICS · PAPER 1 · FOUNDATION & HIGHER
Exam Practice: Particle motion and pressure in gases
Particle motion and pressure in gases · Particle model of matter · Lesson 5 of 6 · 14 marks · 15 minutes
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Instructions
• Answer all the questions.
• Write your answers in the spaces provided.
• The marks for each question are shown in brackets - use this as a guide to how much to write.
• The answers are on separate pages at the back. Attempt every question before you look at them.
• Answer all questions. Use the mark allocation as a guide to how much to write.
Question 1 EXPLAIN (3 marks)
A sealed container of gas is heated and the volume is constant. Explain, in terms of the particles, why the pressure of the gas increases.
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(Total for Question 1 = 3 marks)
Question 2 EXPLAIN (3 marks)
The volume of a gas in a syringe is reduced. The temperature is constant. Explain, in terms of the particles, why the pressure increases.
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(Total for Question 2 = 3 marks)
Question 3 CALCULATE (3 marks)
A fixed mass of gas has a pressure of 100 000 Pa and a volume of 0.30 m³. The gas is compressed at constant temperature to a volume of 0.10 m³. Calculate the new pressure. Use the equation: pressure × volume = constant
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(Total for Question 3 = 3 marks)
Question 4 STATE (1 mark)
State the direction of the force exerted by gas particles on the wall of a container.
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(Total for Question 4 = 1 mark)
Question 5 CALCULATE (4 marks)
A syringe contains 60 cm³ of air at a pressure of 100 kPa. The plunger is pushed in until the volume is 24 cm³. The temperature is constant. Calculate the new pressure of the air in kPa.
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(Total for Question 5 = 4 marks)
TOTAL FOR PAPER = 14 MARKS
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Answers and mark scheme
Check your answer only once you have written one.
Question 1 (3 marks)
The particles gain kinetic energy and move faster. They collide with the walls more often and with greater force, so the force on the walls per unit area increases.
• Particles move faster or gain kinetic energy 1 mark
• Collide with walls more often or harder 1 mark
• So pressure increases 1 mark
Question 2 (3 marks)
The particles are closer together, so they collide with the walls more often. The force per unit area increases, so the pressure increases.
• Volume decreases so the particles are closer 1 mark
• More frequent collisions with the walls 1 mark
• Pressure increases 1 mark
Question 3 (3 marks)
100 000 × 0.30 = p × 0.10; p = 300 000 Pa
• Correct substitution 1 mark
• Rearranges 1 mark
• 300 000 Pa 1 mark
Question 4 (1 mark)
At right angles to the wall.
• At right angles to the wall 1 mark
Question 5 (4 marks)
100 × 60 = p × 24; p = 250 kPa
• pV constant 1 mark
• Correct substitution 1 mark
• Correct rearrangement 1 mark
• 250 kPa 1 mark