Azeotropes are binary mixtures that have the same composition in liquid and vapour phase and boil at a constant temperature.

1. Maximum Boiling Azeotrope: This type of azeotrope is formed by solutions that show large negative deviation from Raoult's law. In such solutions, the intermolecular attractive forces between the solute and solvent (A-B) are stronger than those between the pure components (A-A and B-B). This decreases the vapour pressure and increases the boiling point.

• Nitric acid and Water: As stated in the NCERT text, a mixture of 68% nitric acid and 32% water by mass shows a large negative deviation and forms a maximum boiling azeotrope with a boiling point of 393.5 K .

2. Minimum Boiling Azeotrope: Formed by solutions showing positive deviation from Raoult's law (weaker A-B interactions).

• Ethanol + Water: Shows positive deviation and forms a minimum boiling azeotrope .
• Acetone + Carbon disulphide: Shows positive deviation and forms a minimum boiling azeotrope .

3. Ideal Solution:

• Heptane + Octane: Being homologues, they form a nearly ideal solution and do not form an azeotrope .