Latent heat

 Latent heat is the heat energy absorbed or released by a substance during a phase change (such as melting, freezing, evaporation, condensation, sublimation, or deposition) without a change in temperature. Unlike sensible heat, which causes a change in temperature of a substance, latent heat causes a change in the state of the substance from one phase to another.

There are two types of latent heat:

1. Latent Heat of Fusion: Latent heat of fusion (${𝐿}_{𝑓}$) is the amount of heat energy absorbed or released when a substance changes from a solid to a liquid (melting) or vice versa (freezing) at constant temperature. It represents the energy required to break the intermolecular bonds in a solid or to form those bonds in a liquid. The latent heat of fusion is typically expressed in units such as joules per gram (J/g) or kilojoules per kilogram (kJ/kg).

2. Latent Heat of Vaporization: Latent heat of vaporization (${𝐿}_{𝑣}$) is the amount of heat energy absorbed or released when a substance changes from a liquid to a gas (evaporation) or vice versa (condensation) at constant temperature. It represents the energy required to overcome the intermolecular forces in a liquid to form a gas or the energy released when gas molecules condense into a liquid. Like the latent heat of fusion, the latent heat of vaporization is typically expressed in units such as joules per gram (J/g) or kilojoules per kilogram (kJ/kg).

The latent heat of fusion and vaporization are specific to each substance and depend on factors such as the substance's molecular structure, intermolecular forces, and pressure. These values are essential for understanding and predicting phase changes in substances and are crucial for various applications in fields such as thermodynamics, meteorology, material science, and engineering.

In summary, latent heat is the heat energy involved in phase changes of a substance without a change in temperature, and it includes the latent heat of fusion and vaporization. It represents the energy required to break or form intermolecular bonds during phase transitions.