What is an azeotrope and how can azeotropic mixtures be separated?

An azeotrope is a mixture that boils at constant composition, making separation by simple distillation impossible because liquid and vapor have the same composition. Separation methods include: pressure-swing distillation (azeotrope composition changes with pressure), azeotropic distillation (adding an entrainer that forms a new azeotrope), extractive distillation (adding a solvent that alters relative volatility), and membrane pervaporation.