How Does Azeotrope Form?

Azeotropes can form only when a mixture deviates from Raoult's law, the equality of compositions in liquid phase and vapor phases, in vapour-liquid equilibrium and Dalton's law the equality of pressures for total pressure being equal to the sum of the partial pressures in real mixtures.

When and why are Azeotropes formed?

Azeotropes are a mixture of at least two different liquids. Their mixture can either have a higher boiling point than either of the components or they can have a lower boiling point. Azeotropes occur when fraction of the liquids cannot be altered by distillation.

What forms azeotrope with water?

Another common binary azeotrope found in solvent recycling is acetonitrile and water. This is a common mixture used for HPLC analysis. Acetonitrile boils at 81.6 ºC and water boils at 100 ºC. The mixture forms an azeotrope which boils at 76.1 ºC and which is composed of 86% acetonitrile and 14% water.