|physics the pressure exerted by a vapour. The saturated vapour pressure is that exerted by a vapour in equilibrium with its solid or liquid phase at a particular temperature|
pressure exerted by a vapour when the vapour is in equilibrium with the liquid or solid form, or both, of the same substance-i.e., when conditions are such that the substance can exist in both or in all three phases. Vapour pressure is a measure of the tendency of a material to change into the gaseous or vapour state, and it increases with temperature. The temperature at which the vapour pressure at the surface of a liquid becomes equal to the pressure exerted by the surroundings is called the boiling point (q.v.) of the liquid
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