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.