Which system condition typically requires the addition of latent heat?

The addition of latent heat is specifically associated with the process of evaporation. When a substance, such as water, transitions from a liquid to a gaseous state, it requires energy input in the form of latent heat. This energy is necessary to overcome the intermolecular forces that hold the molecules together in the liquid state, allowing them to escape into the air as vapor.

During evaporation, as heat is absorbed by the liquid, its temperature may remain constant until the liquid has entirely converted to vapor. This implies that the latent heat is used not to increase the temperature of the liquid, but rather to facilitate the phase change.

In contrast, condensation involves the release of latent heat as gas molecules lose energy and transition back into a liquid state. Compression and expansion refer to changes in pressure or volume of a gas, and while these processes can involve heat transfer, they do not specifically pertain to the need for latent heat in the same way that evaporation does.