Enter your vapor pressures of pure A and B, along with the mole fraction of A (or moles of solute/solvent), and this Raoult's Law Distillation Calculator gives you the total vapor pressure plus partial pressures and vapor mole fractions for both components — everything you need to characterize an ideal liquid mixture.
Total Vapor Pressure
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Partial Pressure A
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Partial Pressure B
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Vapor Mole Fraction A
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Vapor Mole Fraction B
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Raoult's law is used to calculate the vapor pressure of ideal solutions and predict vapor-liquid equilibrium behavior. It's essential in distillation design, chemical engineering processes, and understanding how components separate in mixtures.
Raoult's law states that the partial vapor pressure of each component in an ideal solution is equal to the vapor pressure of the pure component multiplied by its mole fraction in the liquid phase.
The Raoult's law equation is Pi = xi × Pi°, where Pi is the partial pressure of component i, xi is its mole fraction in the liquid, and Pi° is the vapor pressure of pure component i.
To calculate mole fraction using Raoult's law, rearrange the equation: xi = Pi / Pi°. You need to know the partial pressure of the component and its pure vapor pressure.
Raoult's law applies most accurately to ideal solutions where molecular interactions between different components are similar to those in pure components. It works best for chemically similar substances and at moderate pressures.
Partial pressure is the pressure exerted by each individual component in a mixture. Total pressure is the sum of all partial pressures according to Dalton's law.
Vapor composition (y-values) differs from liquid composition (x-values) because components with higher vapor pressures are enriched in the vapor phase. This difference enables separation by distillation.