2. contemplated with

3. Combined with Explains almost all Solution behaviors We saw three examples of Colligative Properties: colligative – depends only on the number of particles  T fp = K fp m solute  T bp = K bp m solute  P solv = X solvent P o solvent  T fp = K fp m solute  T bp = K bp m solute  P solv = X solvent P o solvent See why we need to deal with new types of concentration: mole fraction, molality. These relationships depend on numbers of particles

5. Ideal behavior, no association of ions ---------------------------------------------------- 2.00 Ideal behavior, no association of ions ---------------------------------------------------- 3.00 Let’s watch this association ….

6. Combined with Explains almost all Solution behaviors Fourth example of Colligative Properties: Osmosis – the movement of solvent through a semi- permeable membrane from a region of high solute concentration to low solute concentration.

7. pasta marshmallow nut light source Semi- Permeable Membrane bag 5% sugar solution This is the system at equilibrium This is what creates the dis-equilibrium In the beaker

8. pasta marshmallow nut light source The system is disturbed away from equilibrium X H 2 O (outside) ≠ X H 2 O (inside) 100% H 2 O (outside) ≠ 95% H 2 O (inside) The system will respond by shifting equilibrium H 2 O (outside)  H 2 O (inside) How???

9. Only water molecules can move thorough membrane The membrane is invisible to water

10. pasta marshmallow nut light source When the system responds by shifting equilibrium: If diluted to 1% sugar: 0.00278 mol/ 0.095 L = 0.0293 M Using:  = c R T  = 0.0293 M x 0.082057 atm/M K x 298 K  = 0.716 atm or 544 mm Hg The sugar solution under pressure rises up the tube, like a manometer. The height represents the Osmotic Pressure

11. light source Water fills beaker corn syrup pipet fits tightly into hole core of carrot removed and filled with corn syrup Carrot As a membrane

12. pasta marshmallow nut light source

13.  = c R T  in: atm mol/L kelvin .0820 L/atm K Combined with Explains almost all Solution behaviors Osmosis – the movement of solvent through a semi- permeable membrane from a region of high solute concentration to low solute concentration. Osmotic Pressure – the pressure created after the system attains equilibrium, calculated by:

14. Combined with Explains almost all Solution behaviors Semi-permeable membrane: now this is a very special device: selective for molecular size  Size exclusion What is an important example that uses a Semi-permeable membrane? Living cells: have many ways of selecting which molecules get inside or stay outside

15. Previously in Chem 104: Equilibrium & LeChatelier’s Principle 4 (or 3?) Colligative Properties:  P solv = X solvent P o solvent   T bp = K bp m solute   T fp = K fp m solute  = c R T TODAY Example Calcs Equilibrium and Osmosis Examlette Monday For the Future: Enthalpies Do Not Predict Dissolution— they can be exo- and endothermic