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Latent Heat is the heat stored in molecules. It is the now obsolete term introduced by Joseph Black in 1750, derived from the Latin latere, to lie hidden. In thermo chemistry, latent heat (now called phase transition) is the amount of energy in the form of heat released or absorbed by a substance during a change of state as in from a solid to a liquid state or liquid to gaseous state. There are sizeable differences in the amount of latent heat of materials at the molecular level, in their four primary states which are: Solid, Liquid, Gaseous and Plasma (Ultra-super heated gas). These differences require infusion or removal of substantial amounts of energy to transition them from one state to another; it is at this point of transition that the orderly change of sensible heat may not follow an orderly change, as well. . Water, as an example, when refrigerated down in temperature past 32 degrees Fahrenheit will "stall" at 32° sensible temperature while "hidden heat stored in its molecules" is refrigerated out. When sufficient latent heat is removed it will then change its state from 32° sensible heat-temperature liquid water to 32° sensible heat-temperature ice (from a liquid state to a solid state) at which point its sensible temperature will regain a downward trend. So long as refrigeration activities continue to remove heat from the water, the sensible temperature of the water, in solid form, will continue to become colder and colder. . A similar "stall" occurs when heating liquid water up to and past a gaseous state. If one does not trap or contain boiling water, all excess latent heat in the water will transition and escape in the steam that boils off from liquid water whose sensible heat-temperature will remain at 212 degrees Fahrenheit at sea level. From this it would make sense to turn down the source of heat to just enough to keep the water barely boiling once boiling starts, if not pressure cooking, as the water cannot be made any hotter than its boiling point temperature. of 212° sensible heat-temperature. In this case, all excess (latent) heat is carried away in the gaseous steam which went through a change of state from liquid to gas. A pressure cooker allows the water to boil at much higher temperatures before the excess latent heat is released by the steam valve pressure regulator, thus the higher sensible temperature of the pressurized water can cook more efficiently. . High temperature steam under a great deal of pressure can contain vast amounts of latent heat energy and is used to turn turbines and do other useful work by electric and heavy industry and the steam shipping business as well. It is the latent heat in high pressure steam that makes it an efficient source of working energy. . Wikipedia definition of Latent Heat