Surface-molecule collisions make some molecules have enough energy to leave surface and make vapor, which has pressure {vapor pressure}|. Molecules that left liquid before can later fall back into liquid from vapor, so vapor pressure depends on outside pressure and temperature. Substances in liquid mixtures contribute partial pressure to total vapor pressure. Total vapor pressure equals sum of partial pressures. Mixed-liquid vapor pressure is less than pure-liquid vapor pressure. Vapor pressure equals mole fraction times pure-vapor pressure: P = f * P0.
Physical Sciences>Physics>Heat>Phase>Gas
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Date Modified: 2022.0224