GCSE Physics Specific Heat Capacity Notes
Specific heat capacity tells you how much energy it takes to warm a material. Learn the equation and you can calculate the energy for any temperature change.
Key concepts
- Specific heat capacity (c)
- The energy needed to raise the temperature of 1 kg of a substance by 1 °C, measured in J/kg°C.
- Temperature change (Δθ)
- The difference between the final and starting temperature; a larger change needs more energy.
- Why water heats slowly
- Water has a high specific heat capacity (about 4200 J/kg°C), so it stores a lot of energy for each degree of temperature rise.
Key formulas
Thermal energy
ΔE = m × c × Δθ
energy (J) = mass (kg) × SHC (J/kg°C) × temperature change (°C).
Required practicals
- Use an electric heater and thermometer to determine the specific heat capacity of a metal block.
Worked example
How much energy is needed to heat 2 kg of water from 20 °C to 70 °C? (c = 4200 J/kg°C)
- 1Write the equation: ΔE = m × c × Δθ.
- 2Find the temperature change: Δθ = 70 − 20 = 50 °C.
- 3Substitute: ΔE = 2 × 4200 × 50.
- 4Calculate: ΔE = 420 000 J (420 kJ).
Answer: ΔE = 420 000 J (420 kJ)
Common mistakes
✗ Using the final temperature instead of the temperature change.
✓ Δθ = final − starting temperature.
✗ Leaving mass in grams.
✓ Convert mass to kilograms before substituting.
✗ Confusing specific heat capacity with latent heat.
✓ SHC changes temperature; latent heat changes state at constant temperature.
Quick check
Try these, then reveal the answers.
What are the units of specific heat capacity?Reveal answer
Joules per kilogram per degree Celsius (J/kg°C).
Energy to heat 1 kg of a metal (c = 900) by 10 °C?Reveal answer
ΔE = 1 × 900 × 10 = 9000 J
Why does water take a long time to heat up?Reveal answer
It has a high specific heat capacity, so it needs a lot of energy per degree.
Exam tips
- Work out Δθ separately before substituting into the equation.
- Convert mass to kilograms and check the value of c matches the material.
- For the required practical, insulate the block to reduce heat loss to the surroundings.
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Frequently asked questions
What does specific heat capacity mean?+
It is the energy required to raise the temperature of 1 kg of a substance by 1 °C — a higher value means the substance heats up and cools down more slowly.
What is the difference between specific heat capacity and latent heat?+
Specific heat capacity is the energy to change the temperature of a substance; latent heat is the energy to change its state at constant temperature.
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