Question
(a) Define latent heat.
(b) What are dimensions and units of latent heat?
Solution
(a) Latent heat is the heat required to transit the phase of unit mass of a substance at a constant temperature.
Latent heat of fusion: It is the quantity of heat required to transit the phase of 1 g of solid into liquid at constant temperature.
Latent heat of vaporization: It is the quantity of heat required to convert 1 g of liquid into vapours at constant temperature.
(b) Dimensions of latent heat are [M 0L2T–2]
Unit of latent heat is J/kg in SI system and cal/g in cgs system.
