Colligative properties depend only on the number of solute particles, not their nature. Four colligative properties: (1) Relative lowering of vapour pressure (RLVP): $delta_P$/$P_{standard}$ = i * $x_{solute}$. (2) Elevation of boiling point: $delta_{Tb}$ = i * Kb * m. (3) Depression of freezing point: $delta_{Tf}$ = i * Kf * m. (4) Osmotic pressure: pi = i * M * R * T. All four increase with increasing solute concentration. For non-volatile, non-electrolyte solutes: i = 1. For electrolytes: i > 1 (dissociation). For associating solutes: i < 1. Colligative properties are used to determine molar mass: $M_{solute}$ = ($w_{solute}$ x 1000 x Kf) / ($delta_{Tf}$ x $w_{solvent}$) for freezing point depression.