1. Colligative Properties Nonelectrolytes and Electrolytes

2. Boiling Point Elevation Presence of a solute decreases vapor pressure of solvent, so boiling point will be increased More energy required to release more vapor to equal atmospheric pressure Boiling point elevation: ΔT b =K b m K b =molal boiling point elevation constant

3. Osmotic Pressure Osmosis: Movement of solvent across a semipermeable membrane Osmotic pressure: pressure required to stop osmosis (π)‏ π=MRT (M=molarity, T=absolute temperature, R=gas constant (0.0821 Latmo/moleK))‏ Example 12.9

4. Use of Colligative Properties Freezing point depression and osmotic pressure often used to determine molar mass Example 14-5 Example 14-6

5. Colligative Properties for Electrolyte Solutions Electrolytes break into additional particles, so concentration must take that into account van't Hoff factor: i = actual number particles/number of formula units dissolved For instance, NaCl breaks into 2 particles, so i=2