Simple distillation works because the dissolved solute has a much higher boiling point than the solvent. When the solution is heated, solvent vapour evaporates from the solution. The gas moves away and is cooled and condensed. The remaining solution becomes more concentrated in solute as the amount of solvent in it decreases.
Fractional distillation is used to separate different liquids from a mixture of liquids. It is useful for separating ethanol from a mixture of ethanol and water, and for separating different fractions from crude oil.
Fractional distillation works because the different liquids have different boiling points. When the mixture is heated:
There are two ways of obtaining different liquids from the column:
Different liquids can be obtained from different parts of the column, or by continuing to heat the mixture to increase the temperatures in the column.
Distillation process to separate ethanol from water