Specific Heat Capacity (OCR GCSE Physics A (Gateway))
Revision Note
Written by: Ashika
Reviewed by: Caroline Carroll
Calculating Specific Heat Capacity
Specific Heat Capacity describes the energy required to raise the temperature of a substance
The 'specific' part refers to raising the temperature of specifically 1 kg of a substance by 1 degree
Changes to the internal energy of a substance is usually due to transfer of thermal energy
The amount of thermal energy transferred ΔQ is related to the change in temperature Δθ by the equation:
Change in thermal energy = Mass × Specific heat capacity × Change in temperature
ΔQ = mcΔθ
Where:
ΔQ = change in thermal energy, in joules (J)
m = mass, in kilograms (kg)
c = specific heat capacity, in joules per kilogram per degree Celsius (J/kg °C)
Δθ = change in temperature, in degrees Celsius (°C)
Worked Example
Water of mass 0.48 kg undergoes an increase in temperature of 0.7 °C. Calculate the amount of energy transferred to the water during this temperature rise.
The specific heat capacity of water is 4200 J / kg °C.
Answer:
Step 1: Write down the known quantities
Mass, m = 0.48 kg
Change in temperature, Δθ = 0.7 °C
Specific heat capacity, c = 4200 J / kg °C
Step 2: Write down the relevant equation
ΔQ = mcΔθ
Step 3: Calculate the energy transferred by substituting in the values
ΔQ = (0.48) × (4200) × (0.7) = 1411.2
Step 4: Round the answer to 2 significant figures
ΔQ = 1400 J
Examiner Tips and Tricks
This equation will be given on your equation sheet, so don't worry if you cannot remember it, but it is important that you understand how to use it. You will always be given the specific heat capacity of a substance, so you do not need to memorise any values.
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