T - Specific Heat Capacity and Latent Heat - Questions
T - Specific Heat Capacity and Latent Heat - Questions
T - Specific Heat Capacity and Latent Heat - Questions
Q1.
A continuous stream of water falls through a vertical distance of 100 m.
Assume no thermal energy is transferred to the surroundings.
The specific heat capacity of water is 4200 J kg–1 K–1.
What is the temperature difference of the water between the top and bottom of the
waterfall?
A 0.023 K
B 0.23 K
C 2.3 K
D 4.3 K
(Total 1 mark)
Q2.
A student measures the power of a microwave oven. He places 200 g of water at 23 °C
into the microwave and heats it on full power for 1 minute. When he removes it, the
temperature of the water is 79 °C.
What is the average rate at which thermal energy is gained by the water?
A 780 W
B 840 W
C 1.1 kW
D 4.6 kW
(Total 1 mark)
Q3.
A 1.0 kΩ resistor is thermally insulated and a potential difference of 6.0 V is applied to it
for 2.0 minutes. The thermal capacity of the resistor is 9.0 J K–1. The rise in temperature,
in K, is
A 1.3 × 10–3
B 8.0 × 10–3
C 0.48
D 0.80
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(Total 1 mark)
Q4.
(a) Explain what is meant by specific latent heat of fusion.
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(2)
(b) The diagram shows how the temperature of the water is maintained in a hot tub.
The hot tub system has a volume of 4.5 m3 and is filled with water at a temperature
of 28 °C
The heater transfers thermal energy to the water at a rate of 2.7 kW while a pump
circulates the water.
Calculate the rise in water temperature that the heater could produce in 1.0 hour.
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(c) The pump can circulate the water at different speeds.
When working at higher speeds the rise in temperature is greater.
Explain why.
Again assume that no heat is transferred to the surroundings.
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(2)
(Total 7 marks)
Q5.
(a) Which statement explains why energy is needed to melt ice at 0°C to water at 0°C?
Place a tick (✔) in the right-hand column to show the correct answer.
✔ if correct
(b) The diagram shows an experiment to measure the specific heat capacity of ice.
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continuously. Ice is added slowly until all the ice has melted and the temperature of
the water decreases to 0°C. The mass of ice added during the experiment is 0.047
kg.
(i) Calculate the energy required to melt the ice at a temperature of 0°C.
The specific latent heat of fusion of water is 3.3 × 105 J kg–1.
energy = ____________________ J
(1)
(ii) The water loses 1.8 × 104 J of energy to the ice during the experiment.
Calculate the energy given to the ice to raise its temperature to 0°C. Assume
that no energy is transferred to or from the surroundings and beaker.
energy = ____________________ J
(1)
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Q6.
(a) Lead has a specific heat capacity of 130 J kg−1 K−1.
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(1)
(b) Lead of mass 0.75 kg is heated from 21 °C to its melting point and continues to be
heated until it has all melted.
Q7.
A thermometer has a thermal capacity of 1.3 J K–1. The initial temperature of the
thermometer is 20°C. When used to measure the temperature of 40 g of water, it
measures 37°C.
(a) Determine the energy absorbed by the thermometer when it is placed in the water.
(2)
(b) Calculate the temperature change of the water as a result of introducing the
thermometer.
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Q8.
(a) Define the specific latent heat of vaporisation of water.
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(2)
(i) Calculate how much thermal energy is transferred from the copper block as it
cools to 100 °C.
Give your answer to an appropriate number of significant figures.
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(2)
(ii) Calculate how much of this thermal energy is available to make steam.
Assume no heat is lost to the surroundings.
mass ____________________ kg
(1)
(Total 7 marks)
Q9.
An electrical immersion heater supplies 8.5 kJ of energy every second. Water flows
through the heater at a rate of 0.12 kg s–1 as shown in the figure below.
(a) Assuming all the energy is transferred to the water, calculate the rise in temperature
of the water as it flows through the heater.
answer = ____________________ K
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(2)
(b) The water suddenly stops flowing at the instant when its average temperature is 26
°C.
The mass of water trapped in the heater is 0.41 kg.
Calculate the time taken for the water to reach 100 °C if the immersion heater
continues supplying energy at the same rate.
answer = ____________________ s
(2)
(Total 4 marks)
Q10.
In an experiment to measure the temperature of the flame of a Bunsen burner, a lump of
copper of mass 0.12 kg is heated in the flame for several minutes. The copper is then
transferred quickly to a beaker, of negligible heat capacity, containing 0.45 kg of water,
and the temperature rise of the water measured.
(a) If the temperature of the water rises from 15 °C to 35 °C, calculate the thermal
energy gained by the water.
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(2)
(b) (i) State the thermal energy lost by the copper, assuming no heat is lost during
its transfer.
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(iii) Hence calculate the temperature reached by the copper while in the flame.
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(4)
(Total 6 marks)
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Q11.
(a) A student immerses a 2.0 kW electric heater in an insulated beaker of water. The
heater is switched on and after 120 s the water reaches boiling point.
Calculate the specific heat capacity of water if the thermal capacity of the beaker is
negligible.
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(4)
(b) The student in part (a) continues to heat the water so that it boils for 105 s. When
the mass of the beaker and water is measured again, it is found that it has
decreased by 94 g.
(i) Calculate a value for the specific latent heat of vaporisation of water.
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(4)
(Total 8 marks)
Q12.
A female runner of mass 60 kg generates thermal energy at a rate of 800 W.
(a) Assuming that she loses no energy to the surroundings and that the average
specific heat capacity of her body is 3900 J kg–1K–1, calculate
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(3)
(b) In practice it is desirable for a runner to maintain a constant temperature. This may
be achieved partly by the evaporation of sweat. The runner in part (a) loses energy
at a rate of 500 Wby this process.
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(3)
(c) Explain why, when she stops running, her temperature is likely to fall.
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(2)
(Total 8 marks)
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Q13.
An electrical heater is used to heat a 1.0 kg block of metal, which is well lagged. The table
shows how the temperature of the block increased with time.
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(3)
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(2)
(c) The heater provides thermal energy at the rate of 48 W. Use your value for the
gradient of the graph to determine a value for the specific heat capacity of the metal
in the block.
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(2)
(d) The heater in part (c) is placed in some crushed ice that has been placed in a
funnel as shown.
The heater is switched on for 200 s and 32 g of ice are found to have melted during
this time. Use this information to calculate a value for the specific latent heat of
fusion for water, stating one assumption made.
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(3)
(Total 10 marks)
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