Fractional distillation is based on the principle of differential boiling points. It is a separation technique used to separate liquids with different boiling points. When a mixture of liquids is heated, the liquid with the lowest boiling point will evaporate first. This vapor can then be condensed back into a liquid, while the higher-boiling liquids remain in the mixture. By repeating this process, the individual liquids in the mixture can be separated.

Fractional distillation is widely used in the chemical industry, petroleum refining, and other industries where the separation of mixtures is required. For example, fractional distillation is used to separate crude oil into its various components, such as gasoline, diesel, and kerosene.

In fractional distillation, a mixture of liquids is heated in a fractionating column. The column is equipped with a series of plates or trays that are spaced at regular intervals. As the vapor rises up the column, it cools and condenses on the plates. The liquids with lower boiling points condense on the lower plates, while the higher-boiling liquids condense on the upper plates. The condensed liquids then flow back down the column and are collected in separate containers.

The efficiency of fractional distillation can be improved by increasing the number of plates in the column. This provides more surface area for the vapor to condense and increases the separation of the liquids. Fractional distillation is a powerful technique for separating mixtures of liquids and is used in a wide variety of applications.