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Question 1
This question is about the behaviour of ideal gases. |
a) | State what is meant by the internal energy of a gas.
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b) | State two assumptions made about the motion of the molecules in an ideal gas.
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c) | A cylinder of volume 0.015 m3 contains gas at a pressure of 6,750 kPa at a temperature of 23°C. Calculate the number of atoms in the cylinder.
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d) | Explain, in terms of kinetic theory model, why a pressure is exerted by the gas on the piston.
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Question 2
The graph below shows how the pressure varies with volume for an ideal gas. |
a) | At B the temperature of the gas is 12°C. Calculate the temperature of the gas at A. Give your answer in °C.
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b) | Calculate the number of moles of gas in the container.
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c) | Deduce whether the temperature of the gas changes during the compression from B to C.
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Question 3
A student is investigating the relationship between gas pressure and temperature. They seal a gas in a container and heat it in a beaker of water over a bunsen burner. The student records the temperature and pressure of the gas as it is heated. |
a) | Draw a line of best fit on the students results to find the temperature of the gas when the pressure is 0 kPa.
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b) | State the temperature of the gas when the pressure is 0 kPa.
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c) | Specialist equipment is required to reach these temperatures. Describe the motion of the particles in the gas as it is cooled to such low temperatures.
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Question 4
A student is pumping up their bicycle tyre using a manual pump. |
a) | The tyre has a volume of 115 cm3 and contains air at 101 kPa. The pump has a volume of 25 cm3 and contains air at the same pressure. The air enters the tyre via one-way valve to prevent the air escaping. The gas behaves like an ideal gas and obeys the equation below. pressure x volume = constant Calculate the value of the constant before the student pumps the tyre.
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b) | Calculate the pressure of the air in the tyre after one stroke of the pump. Give your answer to the nearest whole number in kPa.
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c) | The student needs to pump the tyre to 431 kPa. Calculate how many strokes of the pump are required to raise the pressure from 101 kPa to 431 kPa. You may assume the pressure increase per stroke remains constant.
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d) | After the required number of strokes, the pressure reading is still not 431 kPa. Suggest a reason why the tyre may not be pumped up to the correct pressure.
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Question 5
A student is investigating the behaviour of gases. |
a) | The student traps a gas at atmospheric pressure in a volume of 0.8 m3. Describe the motion of the particles in the gas.
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b) | The student compresses the the gas into a volume of 0.2 m3. Atmospheric pressure is 101 kPa. Calculate the new pressure of the gas.
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c) | Explain how particles in a gas exert a pressure on the walls of the container.
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Question 6
A student is investigating the relationship between pressure and volume of a gas at constant temperature. |
a) | Before the pump is turned on the gas is at atmospheric pressure, 101 kPa. The volume of the gas in the tube reads 35 cm3. Describe a method the student could follow to obtain results for a pressure vs volume graph.
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b) | The student's results are in the table below. Plot a graph of pressure vs volume for the student's results. Model answer
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c) | Describe the relationship shown by the graph.
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d) | For a fixed mass of gas at constant temperature the gas obeys the equation below. pressure × volume = constant Calculate the constant for the pressure of 161 kPa. Give your answer to 2 significant figures in standard form.
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e) | If the gas is compressed too quickly the temperature of the gas increases. Explain how the temperature increase would affect the pressure exerted by the gas.
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Question 7
A student in investigating the relationship between pressure and volume. They attach a syringe to a pressure gauge. |
a) | State the pressure shown on the pressure gauge.
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b) | Explain what happens to the pressure reading as the piston is inserted further into the syringe.
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c) | The volume of the syringe in the position shown is 10 cm3. pressure x volume = constant Calculate the constant for the syringe above.
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d) | The syringe is inserted until the volume is 2.8 cm3. Calculate the new pressure inside the syringe.
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Question 8
A student traps a fixed mass of gas in a container with a temperature sensor and a pressure sensor. |
a) | Describe how the student could slowly vary the temperature of the gas inside the box between 0°C and 100°C.
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b) | Describe how the motion of the gas particles will change as the gas is heated.
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c) | Explain why the pressure increases when the gas is heated.
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d) | At room temperature 25°C, the pressure in the box was 101 kPa. Calculate the pressure in the box when the temperature is 60°C. Give your answer in kPa to 1 decimal place.
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Question 9
This question is about the behaviour of gases. |
a) | A sealed cylinder contains a fixed mass of gas. What will happen when the piston is pushed further into the cylinder? A pressure of gas decreases B volume of gas increases C temperature of gas decreases D pressure of gas increases
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b) | The initial pressure is 105 kPa and a volume of 12 cm3. Calculate the pressure when the volume is decreased by 4 cm3. Give your answer in kPa to 1 decimal place.
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c) | The piston is then locked in place so that the volume is fixed. The cylinder and piston are placed in a cold room. Describe how the pressure of the gas would vary as the temperature of the gas decreases.
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Question 10
A ball is inflated until it contains 12.2 g of air. The radius of the ball when inflated is 14 cm when the temperature of the air 22°C. The molar mass of air is 29 g mol-1. |
a) | Calculate the pressure of the air inside the ball.
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b) | Describe with reference to kinetic theory, what happens to the pressure on a hot day. You may assume the ball is not able to expand.
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c) | The ball is connected to a cylinder pump of volume 3 x 10-3 m3. The pressure of the air in the pump is 101 kPa at 22°C. A student pushes the handle of the pump down so that all the air in the pump is forced inside the ball. Calculate the new pressure of the ball. You may assume the ball is unable to expand and the temperature of the gas is constant.
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