Vapour Pressure of Liquid-Liquid Solutions
Let’s use two volatile liquid solutions labelled 1 and 2 to calculate the vapour pressure of a liquid-liquid solution. An equilibrium between the binary solution’s liquid phase and vapour phase is created when the liquid components are added to a closed vessel.
Assume that PTotal is the total vapour pressure of the binary solution at equilibrium and P1 and P2 are the respective partial vapour pressures of components 1 and 2. Let the mole fractions of components 1 and 2 be X1 and X2, as the partial pressures are related to the mole fractions.
Vapour Pressure
Vapour pressure is the force exerted by a liquid’s (or solid’s) vapour above the surface of the liquid. At a particular temperature and thermodynamic equilibrium, this pressure is formed in a closed container. The rate of liquid evaporation is controlled by the equilibrium vapour pressure. The vapour pressure increases with increasing temperature. When atmospheric pressure and vapour pressure are equal, a liquid is said to have reached its boiling point.