The most common and simplest law applicable to non-aqueous mixtures is Raoult's law.
It is stated that the partial vapor pressure of each component of the solution is directly proportional to the mole fraction present in the solution, for a solution of volatile liquids.
It can be represented mathematically as:
where is the partial pressure and is the mole fraction of the first component. is the vapor pressure at the same temperature as the pure component.