Which phase change absorbs heat?

During the process of evaporation, a liquid transforms into a gas, which requires the absorption of heat energy. This heat is necessary to overcome the intermolecular forces that hold the molecules of the liquid together. As the molecules gain this energy, they can break free from the liquid state and enter the gaseous state. This phase change is an endothermic process, meaning it absorbs heat from the surroundings, leading to a cooling effect in the remaining liquid. Understanding this concept is essential in applications like sweating in humans, where evaporation of sweat cools the body.

In contrast, the other phase changes mentioned, such as condensation, freezing, and sublimation, either release heat or do not primarily involve the absorption of heat. Condensation involves gas turning to liquid, releasing heat in the process, while freezing is the change from liquid to solid, which also releases heat. Sublimation, on the other hand, is the transition from solid directly to gas, which involves the absorption of heat, but in this context, the focus is specifically on the liquid-to-gas transition characteristic of evaporation.