Specific heat capacity Cambridge IGCSE Physics revision
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In plain words
Different materials need different amounts of energy to warm up. A metal spoon heats through in seconds; the same mass of water takes far longer. Water has a high specific heat capacity, which is why the sea warms up slowly in summer and cools down slowly in winter.
Three things to know
- Specific heat capacity is the energy needed to raise the temperature of 1 kg of a substance by 1 °C.
- Energy = mass × specific heat capacity × temperature change (ΔE = mcΔθ).
- To measure it: heat a known mass with an electrical heater, measure the energy supplied and the temperature rise, and use c = energy ÷ (mass × temperature change). Insulate the block to cut heat losses.
Worked example
How much energy is needed to heat 2 kg of water by 10 °C? (Specific heat capacity of water = 4200 J/kg °C)
- Energy = mass × specific heat capacity × temperature change.
- = 2 × 4200 × 10.
- = 84 000 J.
Tips and tricks
- Use the change in temperature, not the final temperature.
- Mass must be in kilograms. Change grams first.
It lands in your notebook with its questions as flashcards.
Specific heat capacity: 5 questions and answers
These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.
What does a high specific heat capacity mean?
More energy is needed for each degree of temperature rise.
How much energy raises the temperature of 1 kg of water by 2 °C? (c = 4200 J/(kg °C))
1 × 4200 × 2.
2100 J heats 0.5 kg of oil by 2 °C. What is the specific heat capacity of the oil?
2100 ÷ (0.5 × 2) = 2100.
What are the units of specific heat capacity?
Energy for each kilogram and each degree.
The same energy is given to 1 kg of water and 1 kg of copper. Copper has the lower specific heat capacity. Which gets hotter?
Less energy is needed for each degree, so its temperature rises more.
Quiz
5 questions
Tap an answer and you’ll see straight away whether it’s right, and why.
Worksheet
3 questions, 8 marks. Write your answers on paper, then check them.
Specific heat capacity
Cambridge IGCSE Physics 0625 · 8 marks · papermunch.org
Name ______________________________ Date ______________
Calculate the energy needed to heat 2.0 kg of water from 20 °C to 70 °C. Specific heat capacity of water = 4200 J/(kg °C).[3]
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420 000 J. 2.0 × 4200 × 50.
9000 J of energy raises the temperature of a 0.50 kg metal block by 20 °C. Calculate the specific heat capacity of the metal.[3]
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900 J/(kg °C). 9000 ÷ (0.50 × 20).
In an experiment to measure the specific heat capacity of a metal block, the value found is too high. Suggest why.[2]
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Some of the energy supplied was lost to the surroundings, so more energy was needed than the block itself took in.
Answers: Specific heat capacity
- 1. 420 000 J. 2.0 × 4200 × 50.
- 2. 900 J/(kg °C). 9000 ÷ (0.50 × 20).
- 3. Some of the energy supplied was lost to the surroundings, so more energy was needed than the block itself took in.