This lecture covers colligative properties of solutions, such as vapor pressure depression, boiling point elevation, and freezing point depression, which depend only on the identity of the solute particles. It also explains osmosis, the movement of solvent across a semi-permeable membrane from low to high solute concentration, and its applications in desalination processes. The lecture further delves into the concept of osmotic pressure and its calculation, as well as the principles behind separation of immiscible liquids. Additionally, it explores the osmotic behavior of red blood cells and includes interactive questions on the effects of pure water intake after exercise.