Apparatus Image

Osmosis apparatus showing solvent flow from dilute to concentrated solution through a semipermeable membrane

Cue Column | Note Column

What is a solution? | A homogeneous mixture of two or more substances. Solvent = component present in largest quantity; Solute = dissolved component.

4 Colligative Properties? | (1) Relative lowering of VP: $\Delta P$/P° = x_solute; (2) Boiling point elevation: $\Delta Tb$ = iKbm; (3) Freezing point depression: $\Delta Tf$ = iKfm; (4) Osmotic pressure: π = iCRT

Key constants (water)? | Kb = 0.52 K·kg/mol; Kf = 1.86 K·kg/mol; Note: Kf > Kb always

Henry's Law? | p = K_H × x; K_H increases with temperature → gas solubility DECREASES with increasing temperature

Raoult's Law? | P_A = x_A · P°_A; P_total = x_A·P°_A + x_B·P°_B (volatile binary); P = x_solvent·P° (non-volatile solute)

Van't Hoff factor? | i = observed colligative / theoretical colligative; i > 1 (dissociation); i < 1 (association)

Summary

Colligative properties are particle-number dependent. The van't Hoff factor corrects all four formulas for electrolytes. Water's Kf (1.86) > Kb (0.52). Henry's law governs gas dissolution; Raoult's law governs vapour pressure of liquids.