When a substance changes from a gas to a liquid, this process is referred to as what?

The transition of a substance from a gas to a liquid is known as condensation. During this process, the substance releases energy in the form of latent heat. The term "latent heat of condensation" specifically refers to the amount of heat energy released when a unit mass of vapor condenses at constant temperature and pressure.

Understanding this process is crucial in refrigeration and air conditioning, where the phase change of refrigerants is a key aspect of heat exchange and cooling. Condensation plays an essential role in the refrigeration cycle, as refrigerants absorb heat from the environment in their gaseous state and release it when they condense back into a liquid, thus facilitating the cooling process.

Other terms included in the choices pertain to different phase changes. For instance, latent heat of vaporization is the heat required for a liquid to turn into a gas, while latent heat of sublimation refers to the transition from solid to gas. Latent heat of fusion involves the change from solid to liquid. Each of these processes has distinct thermal dynamics that are important to understand in the context of thermodynamics and HVAC systems.