Question

p - nitrophenol and o - nitrophenol are separated by?

Answer 1

Those organic liquids which are quite stable at their boiling points and the impurities present are non-volatile, they are purified with the help of steam distillation. Liquids such ethanol, acetone, benzene, toluene, chloroform, carbon tetrachloride can be purified with the method of simple distillation.

Complete answer:
Distillation is the process of converting a liquid into vapours upon heating and cooling the vapours back to the liquid state. Its one type is steam distillation.
In steam distillation, steam from a steam generator is passed through a heated flask containing the liquid to be distilled. The mixture of steam and the volatile organic compound is condensed and collected. The compound is later separated using a separatory funnel from water.
This process is employed for the distillation of those substances which are insoluble in water, have high molecular mass, have fairly high vapour pressure, and are volatile in steam but the impurities present in them are non-volatile. The process of steam distillation can be applied for the separation of a mixture of $p - nitrophenol$ and $o - nitrophenol$
In this process, the water vapours carry along with vapours of o-nitrophenol which is more volatile and they get condensed in the receiver. P-nitrophenol with higher boiling remains in the distillation flask.

Note:
In this process, a mixture of two immiscible liquids that is water and an organic liquid is heated. Each has its own vapour pressure independently of the other and will exert the same and the mixture will begin to boil at a temperature which is a combination of the sum of the vapour pressure of water and of the organic liquid and that becomes equal to the atmospheric pressure.