IGCSE Physics / Solids, liquids and gases

Specific heat capacity

Edexcel International GCSE Physics (4PH1), chapter 19: Solids, liquids and gases, specification point 5.12P, 5.13P, 5.2P. Free lesson.

Read the revision notes · IGCSE Physics past papers

Specific heat capacity tells you how much energy is needed to warm a substance. The equation ΔQ = m × c × ΔT lets you calculate energy, mass, specific heat capacity or temperature change.

What specific heat capacity means

Specific heat capacity, shown by c, measures how hard it is to warm a substance. It is the energy needed to raise the temperature of 1 kg of the substance by 1 °C. “Specific” means per kilogram. The unit is J/kg °C, or joules per kilogram degree Celsius.

Why water is used in radiators

Water has a high specific heat capacity of about 4200 J/kg °C. This means each kilogram can store lots of energy as it heats up. When hot water flows through a radiator and cools, it gives that energy to the room.

How to use the thermal energy equation

Use ΔQ = m × c × ΔT to link the change in thermal energy to the mass, specific heat capacity and temperature change. The equation is on the equation list. Know what each symbol means, and convert any mass in grams to kilograms first. ΔQ is the change in thermal energy, in joules (J). m is the mass, in kilograms (kg). c is the specific heat capacity, in J/kg °C. ΔT is the change in temperature, in °C. It is final temperature minus initial temperature, not a thermometer reading.

Calculate energy or final temperature

For energy, multiply the mass, specific heat capacity and temperature change. If you are given energy and need a temperature change, rearrange the equation first. The result is a change in temperature, so it may not be the final temperature.

Calculate mass or specific heat capacity

When finding mass or c, substitute the known values first, then divide by the other factors. Keep the unit in your answer, especially for specific heat capacity.

More lessons in Solids, liquids and gases