/vay'peuhr euh zay"sheuhn/, n.1. the act of vaporizing.2. the state of being vaporized.3. the rapid change of water into steam, esp. in a boiler.4. Med. a vapor therapy.[1790-1800; VAPOR + -IZATION]
* * *Conversion of a substance from the liquid or solid phase into the gaseous (see gas), or vapour, phase.It includes boiling, in which vapour bubbles form in a liquid, and sublimation, in which a solid is converted directly to vapour. Vaporization requires that heat (the substance's latent heat of vaporization) be supplied to the liquid or solid; the same amount of heat is released by the substance in condensation, the reverse of vaporization. If the surroundings do not supply enough heat, the temperature of the remaining substance undergoing vaporization drops. See also evaporation.
* * *▪ phase changealso called Evaporation,conversion of a substance from the liquid or solid phase into the gaseous (gas) (vapour) phase. If conditions allow the formation of vapour bubbles within a liquid, the vaporization process is called boiling. Direct conversion from solid to vapour is called sublimation.Heat must be supplied to a solid or liquid to effect vaporization. If the surroundings do not supply enough heat, it may come from the system itself as a reduction in temperature. The atoms or molecules of a liquid or solid are held together by cohesive forces, and these forces must be overcome in separating the atoms or molecules to form the vapour; the heat of vaporization is a direct measure of these cohesive forces.Condensation of a vapour to form a liquid or a solid is the reverse of vaporization, and in the process heat must be transferred from the condensing vapour to the surroundings. The amount of this heat is characteristic of the substance, and it is numerically the same as the heat of vaporization. See also sublimation.
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