Separation of Mixtures :The process of separation of a mixture into its components depends up on the difference in the physical properties such as melting points, boiling points, solubility etc., of various components.

a. Sendimentation or Decantation :The separation of a mixture in which one component is a liquid and the other is an insoluble solid heavier than the liquid.

Ex : Mixture of sand and water can be separated by this method.

b. Filtration :It is used for the complete separation of an insoluble solid from a liquid.

Ex : Mixture of pepper and salt can be separated by dissolving the of mixture in water followed by filteration.

c. Evoparation :It is used to separate a non-volatile soluble salt from a liquid.

Ex : Sodium chloride is obtained from sea water.

d. Sublimation :substances directly changes from solid to vapour state on heating. The vapours on cooling change back to the solid form

$\text{solid}\underset{\text{cool}}{\stackrel{\text{heat}}{\⇌}}\text{vapours}$

$$

It is used for the separation of camphor, naphthalene, anthracene, benzoic acid etc., containing non volatile substances.

e. Distillation :This process involves the conversion of a liquid into its vapours upon heating and then cooling the vapours back into the liquid.

This can be used for separation of

i. a solution of a solid in a liquid

ii. a solution of two liquids whose boiling points differ by 30-80°C.

Ex : Mixture of ethyl alcohol and ether can be separated by this method.

f. Frational distillation :It is used, when the boiling points of two or more miscible liquids lie close together.

Ex : Crude petroleum is separated by fractional distillation into different fractions like gasoline, kerosene oil, diesel, lubricating oil.

g. Extraction with a solvent :It is useful to recover organic compounds from solids or aqueous solutions.

Organic compounds are generally soluble in organic solvents. Organic solvent is immiscible with water so that organic and water layers can be easily separated.

Ex : Benzoic acid from water may be extracted from its aqueous solution by using benzene.

h.Other forms of Separation

i. Gravity Separation :It is used for the separation of a mixture in which the components have different densities.

ii. Magnetic separation :It is used for the separation of mixtures in which one components is magnetic while the other is non-magnetic.

Ex : Iron ore is separated from the non-magnetic impurities.

iii. Chromatography :This method is based on the differences in the rates at whjich the components of a mixture are adsorbed on a suitable adsorbent.

Ex : It is used to 1. Separate ortho and para nitro anilines.

2. Separate blue and red dyes.

Elution: Alumina, Silica, Magnesium oxide or Fulle’s earth (kind of clay) are used as adsorbents. The process of recovery or extraction of the adsorbed components from the adsorbent with the help of suitable solvent is called elution.

Ex : Petroleum Ether, ${\text{CCl}}_{\text{4}},$ Benzene, Alcohol, Acetone.