Like pure solids, liquids and gases, solutions have well-defined physical properties (e.g., vapor pressure, boiling point, etc.). A change in a property of a solvent that depends on the concentration of dissolved solute(s) particles is called a colligative property.

Colligative properties do not depend on the identity of either the solvent or the solute(s) particles (kind, size or charge) in the solution.

Colligative properties are

1. vapor pressure lowering,
2. boiling point elevation,
3. freezing point lowering, and
4. osmotic pressure.

Consider, for example, a solution prepared by dissolving 5.00 g of NaCl in 100 g of pure water at 25^oC and 1 atm pressure. The following table summarizes some of the differences in the properties of pure water and the NaCl solution.