ThermodynamicsEdexcel International A Level Physics: Topic test

20 questions, 54 marks

Edexcel International A Level Physics

Thermodynamics topic test

Total 54 marks

Name

Class

Date

1
An aluminium block of mass 1.5 kg and specific heat capacity 900 J kg⁻¹ K⁻¹ is heated by an electric heater of power 120 W from 20 °C to 60 °C. Assume at first that no energy is transferred to the surroundings.
(a)
How much energy is needed to raise the temperature of the block from 20 °C to 60 °C?
[1 mark]
A8.1 × 10⁴ J
B5.4 × 10⁴ J
C2.7 × 10⁴ J
D1.4 × 10³ J
(b)
How long does the heater take to supply this energy?
[1 mark]
A4.5 × 10² s
B6.5 × 10⁶ s
C6.8 × 10² s
D2.2 × 10⁻³ s
(c)
In practice the heating takes 540 s. Calculate the average rate at which energy is transferred to the surroundings during the heating.
[2 marks]
Total for question 1: 4 marks
2
A fixed mass of an ideal monatomic gas, containing 2.0 × 10²² atoms, is heated in a rigid container from 20 °C to 80 °C. Take the Boltzmann constant k = 1.38 × 10⁻²³ J K⁻¹.
(a)
By what factor does the average kinetic energy of an atom of the gas increase?
[1 mark]
A4.0
B1.1
C0.83
D1.2
(b)
Which statement about the internal energy of this ideal gas is correct?
[1 mark]
Ait is the potential energy of the atoms only
Bit is the kinetic energy of the container only
Cit is the random kinetic energy of the atoms only
Dit is the sum of the random kinetic and potential energies of the atoms, with the potential energy being the larger
(c)
Calculate the internal energy of the gas at 80 °C.
[2 marks]
Total for question 2: 4 marks
3
A diving cylinder of volume 1.5 × 10⁻² m³ contains air, which may be treated as an ideal gas, at a pressure of 2.0 × 10⁷ Pa and a temperature of 290 K. Take the Boltzmann constant k = 1.38 × 10⁻²³ J K⁻¹.
(a)
Calculate the number of molecules of air in the cylinder.
[3 marks]
(b)
The cylinder is left in sunshine and the temperature of the gas rises to 320 K. Calculate the new pressure, and the factor by which the r.m.s. speed of the molecules increases.
[4 marks]
Total for question 3: 7 marks
4
A copper block of mass 2.0 kg at 150 °C is lowered into 0.80 kg of water at 20 °C in a well-insulated container. The specific heat capacity of copper is 385 J kg⁻¹ K⁻¹ and that of water is 4190 J kg⁻¹ K⁻¹. Assume that no energy is transferred to the container or the surroundings and that no water boils.
(a)
Determine the final temperature of the copper and the water, the energy transferred from the copper to the water, and explain why the temperature of the water rises by much less than the temperature of the copper falls.
[6 marks]
(b)
A student says: 'At the final temperature the copper atoms and the water molecules have the same average kinetic energy, so the copper and the water have the same internal energy.' Evaluate the student's statement.
[6 marks]
Total for question 4: 12 marks
5
Neon gas, which may be treated as an ideal gas of atoms each of mass 3.35 × 10⁻²⁶ kg, is in a sealed container at a temperature of 300 K. Take the Boltzmann constant k = 1.38 × 10⁻²³ J K⁻¹.
(a)
What is the average kinetic energy of an atom of neon at this temperature?
[1 mark]
A6.2 × 10⁻²¹ J
B4.1 × 10⁻²¹ J
C1.2 × 10⁻²⁰ J
D2.1 × 10⁻²¹ J
(b)
What is the r.m.s. speed of the atoms?
[1 mark]
A3.7 × 10⁵ m s⁻¹
B3.5 × 10² m s⁻¹
C8.6 × 10² m s⁻¹
D6.1 × 10² m s⁻¹
(c)
Calculate the temperature at which the r.m.s. speed of the neon atoms would be twice its value at 300 K.
[2 marks]
Total for question 5: 4 marks
6
An electric kettle has a heater of power 2.0 kW. When the water is boiling at 100 °C, 0.050 kg of it is turned into steam. The specific latent heat of vaporisation of water is 2.26 × 10⁶ J kg⁻¹. Assume that all of the electrical energy is transferred to the water.
(a)
How much energy is needed to turn 0.050 kg of boiling water into steam?
[1 mark]
A2.3 × 10⁶ J
B2.2 × 10⁻⁸ J
C1.1 × 10⁵ J
D4.5 × 10⁷ J
(b)
How long does the heater take to supply this energy?
[1 mark]
A5.7 × 10⁴ s
B57 s
C1.1 × 10³ s
D1.8 × 10⁻² s
(c)
Explain, in terms of the molecules of the water, why energy has to be supplied to turn water at 100 °C into steam at 100 °C even though the temperature does not change.
[2 marks]
Total for question 6: 4 marks
7
A student uses a 20 W electric heater to determine the specific latent heat of fusion of ice. The heater is placed in a funnel of crushed ice at 0 °C and switched on for 5.0 minutes, and 21.0 g of water drips into a beaker. In a control run of 5.0 minutes with the heater switched off, 3.0 g of water is collected.
(a)
Calculate the specific latent heat of fusion of ice from the results of the student.
[3 marks]
(b)
Explain why the control run is necessary. Calculate the value of the specific latent heat that the student would have obtained without it, and state the percentage error that this would have introduced.
[4 marks]
Total for question 7: 7 marks
8
A rigid, well-insulated container of volume 0.050 m³ holds 2.0 mol of argon, a monatomic gas that may be treated as ideal, at a temperature of 300 K. An electric heater of power 50 W inside the container is switched on for 120 s. Take the Avogadro constant N_A = 6.02 × 10²³ mol⁻¹ and the Boltzmann constant k = 1.38 × 10⁻²³ J K⁻¹. Assume that all of the energy from the heater is transferred to the gas.
(a)
Determine the initial pressure of the argon, the final temperature of the argon and the final pressure of the argon.
[6 marks]
(b)
A second identical container holds 4.0 mol of argon at 300 K and is heated in the same way. A student says: 'There is twice as much gas, so the final pressure will be twice as great as in the first container.' Evaluate the student's statement.
[6 marks]
Total for question 8: 12 marks

End of questions

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).