The specific latent heat of vaporization of a substance is the quantity of heat needed to change unit mass from

The specific latent heat of vaporization is defined as the amount of heat energy required to change a unit mass of a substance from the liquid phase to the vapor (gas) phase without any change in temperature [1]. During this phase transition, the energy absorbed is used to overcome the intermolecular forces of attraction between molecules rather than increasing the kinetic energy of the particles, which is why the temperature remains constant at the boiling point [1]. While the reverse process (vapor to liquid) involves the release of an equivalent amount of energy known as the latent heat of condensation [3], the term 'vaporization' specifically refers to the transition from liquid to gas [5]. Therefore, the quantity of heat needed to change a unit mass from liquid to vapour at a constant temperature accurately describes the specific latent heat of vaporization.

Sources

1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 22: Vertical Distribution of Temperature > Latent Heat > p. 294
2. [2] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 22: Vertical Distribution of Temperature > Explanation > p. 295
3. [3] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 24: Hydrological Cycle (Water Cycle) > 24.3. Condensation > p. 329
4. [5] https://www.sciencedirect.com/topics/earth-and-planetary-sciences/heat-of-vaporization