AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
Specific heat capacity, c, in joules per kilogram per degree Celsius, J/kg…
Full specification wording
Temperature changes in a system and specific heat capacity: specific heat capacity, c, in joules per kilogram per degree Celsius, J/kg °C
Specific heat capacity, c, measures the energy needed to raise the temperature of 1 kg of a substance by 1 °C. Its unit, J/kg °C, shows energy in joules divided by mass in kilograms and…
Checked against the AQA 8464 specification (opens in a new tab) on .
- Point 8 of 10
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Specific heat capacity, c, measures the energy needed to raise the temperature of 1 kg of a substance by 1 °C. Its unit, J/kg °C, shows energy in joules divided by mass in kilograms and temperature change in degrees Celsius. A large c means the substance warms slowly for a given energy supply, so water (about 4200 J/kg °C) heats far more slowly than copper (about 385 J/kg °C). To find c, rearrange E = mc∆θ to c = E ÷ (m × ∆θ), using the energy transferred, the mass heated and the measured temperature rise. In calculations, substitute values with units, compute the denominator first, then divide. This property explains why water is used in heating systems and why coastal climates vary less than inland ones.
What earns the marks
- State that specific heat capacity is the energy required to raise the temperature of 1 kg of a substance by 1 °C.
- Identify the unit J/kg °C as joules per kilogram per degree Celsius and interpret it as energy per unit mass per unit temperature change.
- Use the equation E = mc∆θ and rearrange it correctly to c = E ÷ (m × ∆θ) when specific heat capacity is the unknown.
- Substitute measured values of energy, mass and temperature change into the rearranged equation, keeping consistent units before calculating.
- Compare values of c to explain why one material heats up faster than another for the same energy transfer and mass.
- Interpret a calculated value of c by checking that its magnitude and unit are reasonable for the substance involved.
Common mistakes and how to put them right
Writing the unit as J/kg rather than J/kg °C, which omits the temperature change.
Put it right by including °C because c depends on temperature rise.
Dividing by mass only or by temperature change only.
Put it right by dividing energy by the product of mass and temperature change.
Using the final temperature instead of the temperature change.
Put it right by subtracting the initial temperature from the final temperature before substituting.
Exam tips
- Write the rearranged equation before substituting numbers so the examiner can follow your method clearly.
- Carry units through each line of working and check that they cancel to leave J/kg °C.
- When comparing materials, refer to the value of c: a higher c means a smaller temperature change for the same energy and mass.
Try the lesson
The start of the Temperature changes in a system and specific heat capacity: specific heat capacity, c, in joules per kilogram per degree Celsius, J/kg °C lesson, made from checked teaching notes for this specification point.
Have a go first
What is the correct standard unit for specific heat capacity, c?
Listen
Specific heat capacity, c, measures the energy needed to raise the temperature of 1 kg of a substance by 1 °C. Its unit, J/kg °C, shows energy in joules divided by mass in kilograms and temperature change in degrees Celsius. A large c means the substance warms slowly for a given energy supply, so water (about 4200 J/kg °C) heats far more slowly than copper (about 385 J/kg °C). To find c, rearrange E = mc∆θ to c = E ÷ (m × ∆θ), using the energy transferred, the mass heated and the measured temperature rise. In calculations, substitute values with units, compute the denominator first, then divide. This property explains why water is used in heating systems and why coastal climates vary less than inland ones. A strong answer earns marks for these points. State that specific heat capacity is the energy required to raise the temperature of 1 kg of a substance by 1 °C. Identify the unit J/kg °C as joules per kilogram per degree Celsius and interpret it as energy per unit mass per unit temperature change. Use the equation E = mc∆θ and rearrange it correctly to c = E ÷ (m × ∆θ) when specific heat capacity is the unknown. Substitute measured values of energy, mass and temperature change into the rearranged equation, keeping consistent units before calculating. A common slip: Writing the unit as J/kg rather than J/kg °C, which omits the temperature change. Instead, including °C because c depends on temperature rise. Exam tip: Write the rearranged equation before substituting numbers so the examiner can follow your method clearly.
See it
Key words
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Specific heat capacity
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J/kg °C
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E = mc∆θ
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c = E ÷ (m × ∆θ)
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See every definition
- Specific heat capacity
- The energy needed to raise the temperature of 1 kg of a substance by 1 °C.
- J/kg °C
- Joules per kilogram per degree Celsius, showing energy divided by mass and temperature change.
- E = mc∆θ
- The equation relating energy transferred to mass, specific heat capacity and temperature change.
- c = E ÷ (m × ∆θ)
- The rearranged equation used to find specific heat capacity from energy, mass and temperature rise.
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