Question

A solution made up of mixing two liquids A and B forms an azeotropic mixture at a given composition. Given that pure liquid A boils at lower temperature than pure liquid B, then on fractional distillation of the azeotropic mixture:

• A. Pure A will distill first.
• B. Pure B will distill first.
• C. Both of them will distill over the same composition as in the mixture.
• D. Composition of A in the liquid mixture increases as the distillation progresses.

Answer 1

The correct option is C Both of them will distill over the same composition as in the mixture.

Azeotropic mixtures are constant boiling mixtures. Fractional distillation works on the principle of difference in boiling points.
Since , an azeotropic mixture boils at a constant temperature so, both the components cannot be seperated by fractional distillation
During boiling, composition remains constant in liquid phase as well as the vapour phase.
So (c) is correct.