1. Schedule Today (4/1): Finish Chapter 17
Wednesday (4/3): Start Chapter 11
Should read Sections 11.1 and 11.2
Wednesday (4/5): Chapter 11
Should read through Section 11.4

3. Osmotic Pressure
Why does this happen?

4. Osmotic Pressure
It’s all about vapor pressure (the difference, actually).

5. Boiling-Point Elevation Question
Some people add salt to water when making pasta. Some claim it is because by adding salt we increase the boiling point of the solution and therefore can cook it at a higher temperature, thus preparing it faster. Recall that table salt (NaCl) has a solubility of about 36g in 100.0g of water and that the boiling-point depression constant for water is 0.51°C kg/mol. Determine the boiling point of a saturated solution of NaCl.

6. (Kb = 0.51°C kg/mol, Kf = 1.86°C kg/mol)
Clicker Question
You add a non-volatile solvent to water to use as antifreeze for your car. The freezing point of the solution is -15.0C. Determine the boiling point of this antifreeze.
(Kb = 0.51°C kg/mol, Kf = 1.86°C kg/mol)
a) 95.9C
b) 104C
c) 107C
d) 115C
e) 155C

7. Comparing Measurements…
Suppose you added g of glucose (C6H12O6) to kg of water at 25°C.
What is the expected:
Freezing point of the solution?
Boiling point of the solution?
Osmotic pressure of the solution?

8. (Kb = 0.51°C kg/mol, Kf = 1.86°C kg/mol)
Clicker Question
A leaf of a saltwater plant is able to thrive in an aqueous salt solution (at 25C) that has a freezing point equal to –0.621C. The plant leaf is placed in an aqueous salt solution (at 25C) that has a boiling point of 102C. What will happen to the plant cells in the leaf?
(Kb = 0.51°C kg/mol, Kf = 1.86°C kg/mol)
a) The plant cells will be unaffected.
b) The plant cells will expand and possibly rupture.
c) The plant cells will shrivel.

9. Clicker Question
A 1.0-g sample of a cobalt compound (!!) is dissolved in mL of water. The osmotic pressure of the solution is 2.93 atm at 25C. What is the formula for the cobalt compound in question? Assume ideal behavior.
a) [Co(NH3)5Cl]Cl2
b) [Co(H2O)6]Cl2
c) [Co(NH3)5ONO]Cl2
d) [Co(NH3)5F]F2

10. Ion Pairing
Concentration and nature affect this.