Vacuum distillation is a method of
distillation whereby the pressure above the liquid mixture to be distilled is reduced to less than its
vapor pressure (usually less than
atmospheric pressure) causing evaporation of the most
volatile liquid(s) (those with the lowest
boiling points). This distillation method works on the principle that boiling occurs when the vapor pressure of a liquid exceeds the ambient pressure. Vacuum distillation is used with or without heating the mixture.