1. Starter
Why is a salt /sand mixture spread on roads when they are icy?

2. Colligative Properties
Ch. 13/14: Solutions
Colligative Properties

3. Colligative Properties
depend only on the concentration of solute particles in a solution
does not depend on the identity of particles
What does volatile mean?

4. Vapor Pressure Lowering
vapor pressure of a solvent containing a nonvolatile liquid is lower than the vapor pressure of the pure solvent at the same temperature
solute decreases the concentration of solvent particles at the surface
so they have a lower chance of escaping into gaseous
phase

5. Boiling Point Elevation
a nonvolatile solute lowers the vapor pressure
How is boiling defined?
a higher T is required for the vapor pressure to reach the atmospheric pressure
a nonvolatile solute elevates the boiling point of the solvent
the amount of the elevation depends on concentration of the solute

7. Freezing Point Depression
vapor pressure of solid and liquid are equal at freezing point
nonvolatile solute lowers the vapor pressure so a lower T is needed to decrease the vapor pressure to that of the solid
a nonvolatile solute depresses the freezing point of the solvent
the amount of the depression depends on concentration of the solute

9. Semi-permeable Membrane
a partition that allows solvent particles to pass through but not solute particles
separates a solution and a pure solvent

10. Osmosis the flow of solvent through a semi-permeable membrane
when the system has reached equilibrium, the water levels are different
the pressure of the atmosphere on the solution is too great for the level to rise any further

11. Applications Red blood cells in a hypertonic soln
What protects plant cells from shrinking/bursting?