azeótropía

Azeótropía refers to a specific mixture of two or more substances in which the proportions of the components remain unchanged on boiling or condensation. This behavior occurs because the vapor phase of an azeotropic mixture has the same composition as the liquid phase. Consequently, an azeotrope cannot be separated into its components by simple distillation.

Azeotropes are often encountered when separating liquid mixtures, particularly in processes like fractional distillation. They can be either minimum boiling azeotropes, which boil at a lower temperature than either of the pure components, or maximum boiling azeotropes, which boil at a higher temperature. The formation of an azeotrope is a consequence of the non-ideal behavior of the liquid mixture, where the interactions between different molecules deviate from ideal solution behavior.

Examples of azeotropes include ethanol and water, which form a minimum boiling azeotrope at approximately 95.6% ethanol by mass. Another common example is hydrochloric acid and water, forming a maximum boiling azeotrope. The presence of azeotropes necessitates the use of alternative separation techniques, such as azeotropic distillation with an entrainer, extractive distillation, or membrane separation, when pure components are desired. Understanding azeotropic behavior is crucial in chemical engineering for designing efficient separation processes and for accurately predicting phase equilibria.