Specific Heat Capacity (Oxford AQA IGCSE Physics)

Specific Heat Capacity

• If the temperature of a system increases, this depends on:

  • The mass of the substance heated

  • The type of material

  • The energy input to the system

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

The amount of energy required to change the temperature of one kilogram of the substance by one degree Celsius.

• Different substances have different specific heat capacities

• If a substance has a low specific heat capacity, it heats up and cools down quickly

  • It takes less energy to change its temperature

• If a substance has a high specific heat capacity, it heats up and cools down slowly

  • It takes more energy to change its temperature 

Specific heat capacity examples

• Energy is transferred to the thermal store of a substance 

• The amount of energy needed to raise the temperature of a given mass by a given amount can be calculated using the equation:

• Where:

  • ΔE = change in 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)

Uses of specific heat capacity

• Specific heat capacity is mainly used for liquids and solids

• The specific heat capacity of different substances determines how useful they would be for a specific purpose e.g. choosing the best material for kitchen appliances

  • Good electrical conductors, such as copper and lead, are excellent conductors of heat due to their low specific heat capacity

  • On the other hand, water's high specific heat capacity makes it ideal for heating homes as the water remains hot in a radiator for a long time

Determining specific heat capacity

• The specific heat capacity of a substance can be determined experimentally

• The equipment below can be used to heat an aluminium block with a known mass,

Equipment used for finding the specific heat capacity of an aluminium block

• The joulemeter can be used to measure the amount of energy transferred to the block, , during heating

• The temperature before and after heating can be measured to determine the temperature change,

• The specific heat capacity, , of the aluminium block can then be calculated using the equation: