What does the term 'latent heat of vaporization' refer to?

Latent heat of vaporization specifically refers to the amount of energy needed to convert a unit mass of a substance from a liquid to a vapor phase at a constant temperature. This process occurs without any temperature change, as all the energy supplied is used to overcome the intermolecular forces holding the liquid together, allowing it to enter the gaseous state.

This concept emphasizes that during the phase change (in this case, vaporization), there is no increase in temperature even though energy is being added. It’s critical in various applications, such as in refrigeration and air conditioning systems, where the evaporation of a refrigerant plays a key role in heat absorption.

In contrast, other choices refer to different heat processes: freezing a liquid into a solid pertains to latent heat of fusion, cooling processes involve heat loss, and melting involves heat gained by a solid which also relates to latent heat of fusion. Understanding these distinctions is essential for grasping the concepts related to phase changes and thermal dynamics.