Raoult's law
![Vapor pressure of a binary solution that obeys Raoult's law. The black line shows the total vapor pressure as a function of the mole fraction of component B, and the two green lines are the partial pressures of the two components.](/Images/godic/202502/06/Raoultov_zakon5846.png")
![Positive and negative deviations from Raoult's law. Maxima and minima in the curves (if present) correspond to azeotropes or constant boiling mixtures.](/Images/godic/202502/06/RaoultDeviationPressureDiagram5846.png")
Raoult's law is a law of thermodynamics established by French chemist François-Marie Raoult in 1882. It states that the partial vapor pressure of each component of an ideal mixture of liquids is equal to the vapor pressure of the pure component multiplied by its mole fraction in the mixture.