Question

The purification method where solid substances change from solid to vapor state without passing through the liquid state is called as which of the following?

(a) Sublimation

(b) Crystallization

(c) Distillation

(d) Differential extraction

This question was addressed to me during an internship interview.

My doubt is from Methods of Purification of Organic Compounds in division Organic Chemistry – Basic Principles and Technique of Chemistry – Class 11

Answer 1

Right choice is (a) Sublimation

For explanation I would say: In sublimation, the solid substance transforms directly to the vapor state without entering into the liquid state. This helps in separating sublimable compounds from non-sublimable ones. Whereas the other three, i.e. crystallization, distillation and differential extraction are used when a suitable solvent is involved. In other words, they deal with mainly liquids and not solids alone.