Distillation and fractional distillation.

Distillation is a type of separating process in which two miscible liquids are separated from each other by using their different boiling points. the one with lower boiling point , boils first and its vapours are passed through a condenser for cooling and droplets are received on the other side in a beaker. this process is used in the liquids with at least 25 degrees difference in boiling points. As shown below

It is used in the separation of water and alcohol.

Fractional Distillation

this separating technique is used when the boiling point difference is less than 25 degrees.

here a separate fractionating column is also attached which is filled of glass beads, and it also follows the same path like distillation.

So fractional distillation is a process in which the two miscible liquids having boiling point less than 25 are separated by evaporation followed by condensation. As shown below:

It is used in the refining of crude petroleum into petrol, diesel , kerosene and greases etc