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.
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 Tip
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.
