Why should mixtures with azeotropes be treated with caution during distillation?

Mixtures with azeotropes should be treated with caution during distillation because they cannot be separated completely by distillation. An azeotrope is a mixture of two or more liquids that has a constant boiling point and composition throughout the distillation process. This occurs because the components of the azeotropic mixture have specific interactions that result in a specific ratio of the components that vaporizes together. Since they behave as a single substance during boiling, distillation techniques are unable to isolate the individual components effectively.

For example, when an azeotropic mixture is heated, it vaporizes at a temperature that corresponds to the azeotropic composition instead of the boiling points of the individual components. As a result, when the mixture is distilled, it produces vapor that retains the same composition as the original mixture at the azeotropic ratio, preventing complete separation. This characteristic is crucial to consider because it affects the efficiency and outcome of distillation processes, making it challenging to purify substances that form azeotropes.