Question

Match the type of mixture of compounds in Column I with the technique of separation / purification given in Column II.

	Column I		Column II
A	Two solids which have different solubilities in a solvent and which do not undergo reaction when dissolved in it	$\left(i\right)$	Steam distillation
B	Liquid that decomposes at its boiling point	$\left(ii\right)$	Fractional distillation
C	Steam volatile liquid	$\left(iii\right)$	Simple distillation
D	Two liquids which have boiling points close to each other	$\left(iv\right)$	Distillation under reduced pressure
E	Two liquids with large difference in boiling points.	$\left(v\right)$	Crystallization

Answer 1

(i) Steam distillation

This technique is applied to separate substances which are steam volatile and are immiscible with water. 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.

So, steam volatile liquid can be separated by steam distillation. Hence, the correct match is :

$\left(C\right)\to \left(i\right)$

(ii) Fractional distillation

If the difference in boiling points of two liquids is not much, simple distillation cannot be used to separate them. Hence, the technique of fractional distillation is used when two liquids which have boiling points close to each other. Hence, the correct match is:

$\left(D\right)\to \left(ii\right)$

(iii) Simple distillation

This important method is used to separate

$\left(a\right)$ volatile liquids from non-volatile impurities and

$\left(b\right)$ the liquids having sufficient difference in their boiling points.

Liquids having different boiling points vaporise at different temperatures. The vapours are cooled and the liquids so formed are collected separately.

So, liquids with large differences in boiling point can be separated by simple distillation. Hence, the correct match is:

$\left(E\right)\to \left(iii\right)$


(iv) Distillation under reduced pressure

This method is used to purify liquids having very high boiling points and those, which decompose at or below their boiling points. Such liquids are made to boil at a temperature lower than their normal boiling points by reducing the pressure on their surface.

So, liquids that decomposes at its boiling point can be separated out by distillation under reduced pressure. Hence, the correct match is:

$\left(B\right)\to \left(iv\right)$

(v) Crystallisation

Crystallisation is a purification technique. It is based on the difference in the solubilities of the compound and the impurities in a suitable solvent. The impure compound is dissolved in a solvent in which it is sparingly soluble at room temperature but appreciably soluble at higher temperature.

So, two solids which have different solubilities in a solvent and which do not undergo reaction can be separated out by the crystallisation process. Hence, the correct match is:

$(A\to (v)$

So, the correct matches can be represented as:

$(A\to (v)$, $\left(B\right)\to \left(iv\right)$,
$\left(C\right)\to \left(i\right)$, $\left(D\right)\to \left(ii\right)$, $\left(E\right)\to \left(iii\right)$