Question

Give a brief description of the principles of distillation.

Answer 1

Distillation is the process of separating the components of a liquid mixture using a distillation assembly. It is used for the purification of compounds and sometimes for the separation. During the process of distillation, the liquid mixture is heated to a certain temperature and based on the boiling points of its components they are separated.

Complete step by step answer:
Let us understand the process of distillation in a broader perspective:
Distillation is a technique that is used for the separation of a volatile liquid from a mixture of non-volatile impurities or for the separation of two volatile liquids.
The process is based on the difference in boiling points of the components.
The mixture is heated and during the heating, the volatile compound with lower boiling point starts boiling and gets converted into gaseous form that is then separated. This then condenses and the liquid is separated from the rest of the mixture.
For example, if you have to separate a mixture of methanol and water, where methanol is a volatile liquid. The mixture is heated using a heat source, methanol having a boiling point of $64.7^oC$, starts boiling first between the temperature range of $63-66^oC$ and gets converted into vapour. While the water which has a higher boiling point of $100^oC$ remains in a liquid state. The methanol vapours are then collected separately and are condensed back into the liquid state. Thus methanol is separated from the water.
Please note that distillation can only be used if the components of the mixture have a difference of $10^oC$ in their boiling point.

Note: During our discussion, we came across a term, ‘volatile liquids’. Let us understand it. A substance is termed as a volatile substance that evaporates easily at room conditions or the one having measurable vapour pressure.