Specific Latent Heat - GCSE Physics Definition

Specific latent heat is the amount of energy needed to change the state of 1 kilogram of a substance without changing its temperature, and it is a property of a substance. There is no temperature change because energy is used to create or break bonds, rather than increasing temperature, allowing the substance to change state. For example, when ice melts into water, it takes in energy to change state, even though the temperature remains constant at 0°C.

There are two types of latent heat; specific latent heat of fusion, which is the energy required to melt or freeze a substance, and specific latent heat of vaporisation, which is the energy needed to boil or condense a substance. Understanding specific latent heat helps explain how substances behave when they melt, freeze, boil, or condense.

The amount of energy stored or released can be calculated using the following:

Where:

• is the changed in thermal energy (in joules, J)

• is the mass (in kilograms, kg)

• is the specific latent height (in joules per kilogram, J/kg)