Chapter Colligative Properties: Property of the solvent that depends on the number, not the identity, of the solute particles. 2 assumptions: no interactions between solvent and solute dilute solutions 5 colligative properties: solubility vapor pressure lowering

Chapter 112 Freezing point depression Osmotic pressure,  where M is molarity where K f is a constant (see Table 11.5) Boiling point elevation where K b is a constant (see Table 11.5)

Chapter 113 Vapor Pressure Lowering (Raoult’s Law, Ideal Solution Law) Vapor more disordered than liquid Pure liquid Solution; more disordered than pure liquid Lower drive to escape to disordered vapor because solution is more disordered than pure liquid ENTROPY

Chapter 114 Example problem: What mass of urea, CON 2 H 4, must be added to 450 g water to get a solution with a vapor pressure of 29.3 mmHg? The vapor pressure of pure water is 31.8 mmHg at this temperature. Write the appropriate equation (Raoult’s Law) write the known and unknown quantities known: P solution, P pure solvent unknown: X (what is X?) write out the definition of X write the known and unknown quantities solve for moles, then mass urea (how?)

Chapter 115 where P A and P B are vapor pressures of A and B in the mixture, and P A ° and P B ° are vapor pressures of pure A and pure B; X A and X B are mole fractions of A and B in the liquid

Chapter 116 Example: The vapor pressures of CCl 4 and C 6 H 12 are and bar, respectively. The vapor pressure of a mixture with X CCl4 =0.5 is (0.530 bar / bar / bar). answer:

Chapter 117 Question: Vapor pressure of the solution is (higher than / lower than / same as) the pure solvent; therefore the boiling point of the solution is (higher than / lower than / same as) the pure solvent.

Chapter 118 Freezing Point Depression: Question: The solution is (more / less) disordered than the pure solvent; therefore the freezing point of the solution is (higher than / lower than / same as) the pure solvent. l S Sol’n S solid is more ordered than l or sol’n sol’n less ordered than pure liquid: must go to lower temp. to freeze liquid and solid are same substance

Chapter 119 time apply pressure sol’n more dilute so more disordered Osmotic Pressure,  / Osmosis sol’n pure solvent semi-permeable membrane: lets solvent, not solute pass through pure solvent sol’n pure solvent  Entropy is the driving force!

Chapter 1110 Molecular Cartoon of Osmosis Question: A 1.0 M CaCl 2 solution has an osmotic pressure (lower than / higher than / the same as) a 1.0 M glucose solution.

Chapter 1111 read only.

Chapter 1112 read only.