What is the Difference Between Azeotropic and Zeotropic Mixture?

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The main difference between azeotropic and zeotropic mixtures lies in their boiling points and the behavior of their components during phase changes.

Azeotropic Mixture:

  • Azeotropic mixtures have a constant boiling point, meaning that the vapor and liquid phases have the same concentration.
  • The dew point and bubble point of an azeotropic mixture are the same.
  • Azeotropic mixtures are difficult to separate using simple distillation due to their constant boiling point.
  • Examples of azeotropic mixtures include water and hydrochloric acid.

Zeotropic Mixture:

  • Zeotropic mixtures, also known as non-azeotropic mixtures, have different boiling points for their liquid components.
  • The dew point and bubble point of a zeotropic mixture are different.
  • Zeotropic mixtures exhibit a temperature glide, meaning that the phase changes of the liquid components take place in a series of temperatures rather than at a single temperature.
  • Zeotropic mixtures have more predictable properties based on the combinations of the pure components' properties.

In summary, azeotropic mixtures have a constant boiling point and a single temperature for phase changes, while zeotropic mixtures have different boiling points for their components and exhibit a temperature glide during phase changes.

Comparative Table: Azeotropic vs Zeotropic Mixture

Here is a table comparing the differences between azeotropic and zeotropic mixtures:

Property Azeotropic Mixture Zeotropic Mixture
Boiling Point Constant boiling point Different boiling points
Vapor-Liquid Composition Constant composition throughout the distillation process Varying composition during distillation
Separation Potential Difficult to separate components because the composition remains constant Easier to separate components due to changing compositions

Azeotropic mixtures have a constant boiling point and a similar composition in their vapor and liquid phases. The composition of the vapor phase is the same as the liquid phase, making it difficult to separate the components using simple distillation. Examples of azeotropic mixtures include water-ethanol and acetone-chloroform.

On the other hand, zeotropic mixtures have different boiling points and varying compositions during distillation. The individual components do not undergo evaporation or condensation at the same temperature, leading to a temperature glide. Zeotropic mixtures can be separated by distillation, whereas azeotropic mixtures cannot be separated by simple distillation.