__Latent Heat of Vaporization:__

The amount of heat required by the unit mass of a liquid to change into its vapor at a constant temperature is called the **latent heat of vaporization** of the liquid.

For any substance, the latent heat of vaporization is the latent heat of condensation. It is denoted by L. Thus if a quantity H of heat is given or extracted to change the state of mass m, for vaporization or condensation respectively then, **H = mL**.

Unit of L in SI system is **J.kg ^{-1}**.

__Latent Heat of Condensation:__

The amount of heat extracted from the unit mass of vapor to change it into its liquid state at a constant temperature is called the **latent heat of condensation**.