1. Colligative Properties

2. Doesn’t depend on identity, but number of particles Boiling Point Elevation (BPE) – addition of solute raises Boiling Point Freezing Point Depression (FPD) – addition of solute lowers Freezing Point The reason for this is a bit complicated, just know that the addition of a solute lowers the vapor pressure, thus changing the BP and FP Antifreeze! – What is the purpose of antifreeze? – Is the proportion of antifreeze to water important? YES! Keeps water in radiator from freezing AND keeps it from boiling when engine is running

3. FORMULAS for Colligative Properties Molality = moles of solute∆FP = mK f i kg of solvent∆BP = mK b i Each solvent is affected differently by the addition of solute particles Molal freezing point constant for water, K f = 1.86°C/m Molal boiling point constant for water, K b =.512°C/m The number of particles dissolved in the solution is what matters, not the identity of the particles Molecular substances dissociate from each other, but remain as discrete molecules Ionic substances break apart into ions, so each unit actually releases at least 2 particles (ions) into solution C 6 H 12 O 6(s)  C 6 H 12 O 6(aq) 1 particle NaCl (s)  Na + (aq) + Cl - (aq) 2 particles CaCl 2(s)  Ca +2 (aq) + 2Cl - (aq) 3 particles i

4. Other units of concentration % by Volume = volume of solute x 100% volume of solution % by mass = mass of solute (g) x 100% mass of solution Molality, m = moles of solute kg of solvent Parts Per Million (ppm)