Specific Heat Capacity (Edexcel IGCSE Physics (Modular): Unit 1): Revision Note

Specific heat capacity

• The specific heat capacity, c of a substance is defined as:

The amount of energy required to raise the temperature of 1 kg of the substance by 1 °C per kilogram of mass (J/kg °C)

• Different substances have different specific heat capacities

  • If a substance has a low specific heat capacity, it heats up and cools down quickly (ie. it takes less energy to change its temperature)

  • If a substance has a high specific heat capacity, it heats up and cools down slowly (ie. it takes more energy to change its temperature)

Examples of specific heat capacity

Low vs high specific heat capacity

• How much the temperature of a system increases depends on:

  • The mass of the substance heated

  • The type of material

  • The amount of energy put into the system in the form of thermal energy

Calculating specific heat capacity

• The specific heat capacity of a substance can be calculated using the equatiion:

$\mathrm{change}\mathrm{in}\mathrm{thermal}\mathrm{energy}=\mathrm{mass}\times \mathrm{specific}\mathrm{heat}\mathrm{capacity}\times \mathrm{change}\mathrm{in}\mathrm{temperature}$

$\mathrm{\Delta }Q=mc\mathrm{\Delta }T$

• 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)

  • ΔT = change in temperature, in degrees Celsius (°C)