Question

Organic solids can be purified by:
A) Steam distillation
B) Crystallization
C) Fractional distillation
D) Simple distillation

Answer 1

Hint: For any organic compound purification process is necessary. There are various methods through which we can purify organic solids. By knowing the nature of organic compound we can decide which method of purification we should use. Basically, purification is the process of removing unwanted impurities.

Complete step-by-step answer:
Distillation is a process through which we can separate compounds from a mixture of liquids with the help of difference in their boiling points. Now the boiling point is basically the temperature at which the vapour pressure of a liquid gets equal to atmospheric pressure. This method is mainly used to purify liquids.

In distillation, there are different types such as simple distillation, steam distillation, fractional distillation, vacuum distillation which are basically used to remove impurities from a liquid mixture that is why we cannot use this method to purify organic solids.

Crystallisation is a process of precipitating solid from its uniform solution. Here, the difference in solubility of compound and impurities in a solvent help for purifying process. In this method, we choose a solvent where the required compound can be purified which is soluble at a higher temperature. The whole solution is heated which results in a saturated solution and we cool that afterwards when the crystals of the compounds are filtered through filtration. Hence, organic solids can be purified by using the crystallisation method.

Hence, the correct answer is option ‘B’.

Note: There are other methods of purification such as sublimation, differential extraction and chromatography. The easiest way for purification is to boil or melt the compounds as they tend to have sharp boiling and melting points.