Latent heat

Latent heat is energy released or absorbed, by a body or a thermodynamic system, during a constant-temperature process that is specified in some way. An example is latent heat of fusion for a phase change, melting, at a specified temperature and pressure. The term was introduced around 1762 by Scottish chemist Joseph Black. It is derived from the Latin latere (to lie hidden). Black used the term in the context of calorimetry where a heat transfer caused a volume change while the thermodynamic system's temperature was constant.

In contrast to latent heat, sensible heat involves an energy transfer that results in a temperature change of the system.

Usage

The terms ″sensible heat″ and ″latent heat″ are not special forms of energy; instead they measure two kinds of change in a material or in a thermodynamic system. ″Sensible heat″ measures change in a body's internal energy that may be ″sensed″ with a thermometer. ″Latent heat″ measures change in internal energy that seems hidden from a thermometer – the temperature reading doesn't change. Heat is energy in the process of transferring between a system and its surroundings, other than as work or by transfer of matter.