A colligative property is a physical property that is independent of the size, mass, or characteristics of the solute particles present in a solution. Instead, it depends on the concentration of the solution, in other words, the number of solute particles present in the solution. The word colligative means "depending on the collection." There are four different types of colligative properties. These are vapor pressure reduction, boiling point elevation, freezing point depression, and osmotic pressure. The latter three properties are directly proportional to the molality of the dissolved solute, which is defined as the number of moles of solute per kilogram of solvent.

Vapor pressure is due to the presence of gas molecules over a liquid surface. Molecules constantly pass from the liquid to the vapor phase, and then in the reverse direction. Vaporization and condensation occur simultaneously. When these two opposing processes are in equilibrium...