AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
Change in thermal energy = mass × specific heat capacity × temperature…
Full specification wording
Temperature changes in a system and specific heat capacity: change in thermal energy = mass × specific heat capacity × temperature change
This relationship lets you calculate the thermal energy transferred when a substance changes temperature without changing state.
Checked against the AQA 8464 specification (opens in a new tab) on .
- Point 4 of 10
- 3 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
This relationship lets you calculate the thermal energy transferred when a substance changes temperature without changing state. The change in thermal energy equals the mass of the substance multiplied by its specific heat capacity and by the temperature change. Specific heat capacity is the energy needed to raise 1 kg of a material by 1 °C, so it links energy, mass and temperature rise. For example, heating 2 kg of water (specific heat capacity 4200 J/kg °C) through 30 °C requires 2 × 4200 × 30 = 252000 J, or 252 kJ. The temperature change is the final temperature minus the initial temperature, and it is the same size in °C and K. Use this equation only when the substance remains in one state; melting or boiling needs a different equation.
What earns the marks
- State the equation as change in thermal energy = mass × specific heat capacity × temperature change.
- Identify the correct values of mass, specific heat capacity and temperature change from the question, converting units where necessary.
- Calculate the temperature change by subtracting the initial temperature from the final temperature, or by reading the change directly from the question.
- Substitute values into the equation and evaluate the product correctly, including powers of ten.
- Give the answer with the correct unit, usually joules (J) or kilojoules (kJ), and an appropriate number of significant figures.
Common mistakes and how to put them right
Using the final temperature instead of the temperature change.
Put it right by calculating final temperature minus initial temperature before substituting.
Forgetting to convert grams to kilograms or minutes to seconds.
Put it right by checking that mass is in kg and any energy unit is consistent with J.
Mixing up specific heat capacity with specific latent heat.
Put it right by remembering that specific heat capacity is used for temperature changes, while specific latent heat is used for changes of state.
Exam tips
- Write the equation first, then rearrange it if the question asks for mass, specific heat capacity or temperature change.
- Show each substitution clearly so that method marks can be awarded even if the final arithmetic is wrong.
- Check that the temperature change is positive when the substance is heated and negative when it is cooled, and include the sign if the question asks for energy transferred from the substance.
Try the lesson
The start of the Temperature changes in a system and specific heat capacity: change in thermal energy = mass × specific heat capacity × temperature change lesson, made from checked teaching notes for this specification point.
Have a go first
A 2 kg block of aluminium is heated and its temperature rises by 5 °C. The specific heat capacity of aluminium is 900 J/kg °C. Calculate the change in thermal energy of the block.
Listen
This relationship lets you calculate the thermal energy transferred when a substance changes temperature without changing state. The change in thermal energy equals the mass of the substance multiplied by its specific heat capacity and by the temperature change. Specific heat capacity is the energy needed to raise 1 kg of a material by 1 °C, so it links energy, mass and temperature rise. For example, heating 2 kg of water (specific heat capacity 4200 J/kg °C) through 30 °C requires 2 × 4200 × 30 = 252000 J, or 252 kJ. The temperature change is the final temperature minus the initial temperature, and it is the same size in °C and K. Use this equation only when the substance remains in one state; melting or boiling needs a different equation. A strong answer earns marks for these points. State the equation as change in thermal energy = mass × specific heat capacity × temperature change. Identify the correct values of mass, specific heat capacity and temperature change from the question, converting units where necessary. Calculate the temperature change by subtracting the initial temperature from the final temperature, or by reading the change directly from the question. Substitute values into the equation and evaluate the product correctly, including powers of ten. A common slip: Using the final temperature instead of the temperature change. Instead, calculating final temperature minus initial temperature before substituting. Exam tip: Write the equation first, then rearrange it if the question asks for mass, specific heat capacity or temperature change.
Key words
Say what each word means before you turn the card.
Specific heat capacity
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Temperature change
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Change in thermal energy
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See every definition
- Specific heat capacity
- The energy needed to raise 1 kg of a material by 1 °C, linking energy, mass and temperature rise.
- Temperature change
- The final temperature minus the initial temperature, the same size in °C and K.
- Change in thermal energy
- The mass of the substance multiplied by its specific heat capacity and by the temperature change.
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