Chapter 11: Colligative Properties Flashcards
What is vapor pressure?
Vapor pressure is the pressure exerted by a gas in equilibrium with a liquid.
It is when the rates of evaporation and condensation are equal
Why does pure water evaporate quicker than sea water?
Because pure water has a higher vapor pressure. The vapor pressure of the sea water has been lowered by the particles in it.
What effects vapor pressure and how do they effect it?
Temperature: T increases, KE increases, Pvap Increases
IMF: IMF increases Pvap decreases (more KE needed Pvap decreases)
Presence of nonvolatile solute: affecting rate of evaporation decreasing vapor pressure (sea water Pvap slower than pure water)
What is Raoult’s law and what is it used for?
Psolution = Xsolvent x P*solvent
Vapor pressure of solution is equal to the vapor pressure of the pure solvent multiplies by the mole fraction of the solvent in the solution
What causes the lowering of vapor pressure?
The colligative property of solutions
What is an ideal solution?
A solution that obeys Raoult’s law
What is fractional distillation?
This is a method by which to separate a mixture based on their different boiling points (evaporate, condense, cool)
How do real solutions differ from ideal solutions?
Total pressure is below the ideal: negative deviations
Total pressure is above the ideal: positive deviations
What do changes in boiling and freezing points depend on?
Molality (n solute/ kg solvent)
Molarity does not work because it changes with temperature as it deals with volumes (Liters)
What is BPE?
Boiling point elevation. ATb = Kb m
What is FPD?
Freezing point depression: ATf= Kf m
What is a nonvolatile solute?
A solute that does not exert a vapor pressure when it dissolves in a liquid
What is the van’t Hoff factor for all nonelectrolytes?
1
Hypotonic:
Solution that has a lower concentration of dissolved substances than plasma
Hypertonic:
Solution that has a greater concentration of dissolved substances than plasma
