Question

Multiple choice

In distillation separation, breaking of azeotropes can be achieved

a. by changing system pressure

b. by adding an entrainer

c. by adding a solvent and using Liquid-Liquid extraction

d. by all of the above methods

Answer 1

An azeotrope is a constant-boiling mixture

Composition of liquid (x_i) = composition of the vapour (y_i)

At such conditions, components of the mixture cannot be separated by using fractional distillation column.

(a) By changing system pressure -

Azeotropes depends on the pressure, by changing the pressure from the current (ambient) pressure the azeotrope will be different. On increasing the pressure, Positive Azeotropes are formed. On decreasing the pressure, negative Azeotropes are formed.

(b) Azeotrope eliminates by adding an entrainer and forms a lower boiling azeotrope. And then three components (in binary system) can be separated by extractive distillation or decantation

(c) Azeotrope eliminates by adding a solvent changes the relative volatility and the new formed mixture can be separated by using Liquid-Liquid extraction.

By all of the above methods.

Option D is the correct answer