Frictional distillation is the method which is used to separate the components of mixture which have two or more than two miscible liquid whose boiling points are differ by 25• c or less than it .
An example of it is methyl alcohol whose boiling point is 65• c can be separated from acetone use boiling point is is 56•c by this method.

Fractional Distillation

Fractional distillation is a process used to separate a mixture of two or more liquids with different boiling points. It is commonly used in industries to separate crude oil into its various components such as gasoline, diesel, and kerosene. This process takes advantage of the fact that different substances have different boiling points, allowing them to be separated based on their vaporization temperatures.

Process of Fractional Distillation

Fractional distillation involves several steps to separate the mixture. These steps include:

1. Vaporization: The mixture is heated in a distillation flask until it reaches its boiling point. The substance with the lower boiling point will vaporize first.

2. Condensation: The vaporized substance then enters a fractionating column, which is a long tube packed with glass beads or metal plates. As the vapor rises through the column, it cools down and condenses into liquid form.

3. Separation: The liquid then flows down the column, where it is reheated by the rising vapor. This process of vaporization and condensation occurs repeatedly as the liquid travels up and down the column. The substances with lower boiling points will rise higher in the column before condensing.

4. Collection: The separated liquids are collected in different compartments called receivers. Each compartment collects the liquid at a specific temperature range, allowing for the separation of different components.

Example of Fractional Distillation: Separating Crude Oil

One example of fractional distillation is the separation of crude oil. Crude oil is a mixture of hydrocarbons with varying boiling points. By subjecting crude oil to fractional distillation, it can be separated into various fractions, each containing hydrocarbons with similar boiling points. Here is how the process works:

1. Crude oil is heated in a distillation tower, also known as a fractionating column.

2. As the temperature increases, different fractions of crude oil vaporize and rise up the column. The substances with lower boiling points, such as gasoline and lighter hydrocarbons, vaporize first and rise higher in the column.

3. As the vapor rises, it cools down and condenses into liquid form. The liquids with higher boiling points, such as diesel and heavier hydrocarbons, condense and collect lower in the column.

4. The separated fractions are collected at different levels in the column. The lighter fractions, such as gasoline, are collected at the top, while the heavier fractions, such as diesel and residual oil, are collected at the bottom.

5. Further refining processes may be applied to each fraction to obtain the desired end products, such as gasoline, jet fuel, lubricants, and asphalt.

By using fractional distillation, crude oil can be effectively separated into its various components, allowing for the production of different petroleum products.