Azeotropes (Constant Boiling Mixtures) (At azeotropic composition: x_liquid = x_vapour → distillation fails; boiling point =)
jee-mainjee-advancedneet-ug
At azeotropic composition: x_liquid = x_vapour → distillation fails; boiling point = constant
What each symbol means
| Symbol | What it stands for |
|---|---|
| x_liquid | Mole fraction in liquid phase at azeotrope |
| x_vapour | Mole fraction in vapour phase at azeotrope |
| max-boiling | Negative deviation from Raoult's law (e.g., HCl-water, HNO₃-water) |
| min-boiling | Positive deviation from Raoult's law (e.g., ethanol-water 95.6%) |
When to use this
Azeotropes form when non-ideal solutions have large enough deviation from Raoult's law. Min-boiling azeotrope: positive deviation, b.p. < either pure component. Max-boiling azeotrope: negative deviation, b.p. > either pure component.