mixture of two or more liquids whose proportions do not change following distillation

Azeotropes are the mixtures of liquids which boil at a constant temperature. Azeotropes may be called constant boiling point mixtures or azeotropic mixtures.[1]

Vapour–liquid equilibrium of 2-propanol/water showing azeotropic behaviour

Their proportions cannot be altered by simple distillation.

Azeotropes are classified into two types

  1. Minimum boiling azeotrope
  2. Maximum boiling azeotrope


  1. Moore, Walter J. 1962. Physical chemistry. 3rd ed Prentice-Hall, p140–142.