Vapour Pressure
The vapour pressure is the equilibrium pressure from a liquid or a solid at a specific temperature. The equilibrium vapour pressure of a liquid or solid is not affected by the amount of contact with the liquid or solid interface.
The normal boiling point of a liquid is the temperature at which the vapour pressure is equal to one atmosphere (unit).
For two-phase systems (e.g., two liquid phases), the vapour pressure of the system is the sum of the vapour pressures of the two liquids. In the absence of stronger inter-species attractions between like-like or like-unlike molecules, the vapour pressure follows Raoult's Law, which states that the partial pressure of each component is the product of the vapour pressure of the pure component and its mole fraction in the mixture. The total vapour pressure is the sum of the component partial pressures.
Read more about this topic: Vapor
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