Colligative Properties of Solutions
By: Ben Griesmer 1°
Colligative Properties
Vapor Pressure Lowering (VPL)
VPL Equations
Change in Vapor Pressure of the Solvent: △P(Solv)=X(Solute) P°(Solv)
Change in vapor pressure of the Solution: P(Solv)=P°(Solv)-△P(Solv)
Mole Fraction of the Solvent: P(Solv) = X(Solv) P°(Solv)
VPL Vocabulary
2. Colligative Property: A property of solutions that is directed by the ratio of solute to solvent regardless of the identity of the solute
3.Raoult's Law: States that the vapor pressure of an ideal solution is directly dependent on the vapor pressure of each chemical component and the mole fraction of the component present in the solution.
Facts about VPL
2. Although many Chefs add salt to water to make it boil faster, it actually does the opposite and makes it take longer to boil.
Freezing Point Depression (FPD)
FPD Equations
Calculate The Freezing Point Depression: △T = -Kfm
The Freezing Point of the Solvent In A Solution
Containing a nonvolatile nonelectrolyte: T(Solution) = T(Pure Solvent) +△T
Change in Freezing point relative to pure solvent: ΔTf=Kfm
FPD Vocabulary
2.Vapor Pressure: The vapor that which a pressure exerts, or the partial pressure if mixed with other gasses
3. van t'Hoff factor: A measure of the effect of a solute on colligative properties
4.Freezing point: The point at which a liquid freezes, and the solid and liquid phases are in equilibrium
FPD Facts
2. When a substance starts to freeze the molecules slow down to to the decrease in temperature.
Boiling Point Elevation (BPE)
BPE Equations
change in boiling point of the solvent above a solution from that of the pure solvent is directly proportional to the molal concentration of the solute: △T = Kbm
BPE Vocabulary
2. Boilng Point Elevation: The temperature at which a substance's vapor equals the external pressure when another compound is added.
3. Water Vapor: Liquid H2O in a gaseous form, often caused by hot temperatures.
BPE Facts
2. Boiling Point elevation will cause water to boil. Boiled water can turn into water vapor which is the reasons we have clouds and rain.
Osmotic Pressure (OP)
OP Equations
Calculate the Osmotic Pressure: π = MRT
OP Vocabulary
2. Osmosis: The net movement of solvent molecules from a region of high solvent potential to a region of lower solvent potential through a partially permeable membrane
3. Ideal Solution: A solution with thermodynamic properties analogous to those of a mixture of an ideal gas
4. Semi-Permeable Membrane: A membrane that will allow only certain molecules or ions to pass through it by diffusion
OP Facts
2. Osmotic Pressure is most commonly associated with water, however it can be used to explain a large varieties of phenomenons. Osmotic pressure is a huge factor in human and other animals blood in making sure it has the correct volume of salt and water.
Sources
http://www.chem.purdue.edu/gchelp/howtosolveit/Solutions/fp_depression.html
http://www.chem.purdue.edu/gchelp/solutions/eboil.html
http://www.encyclopedia.com/topic/Colligative_Properties.aspx
http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch15/colligative.php
http://www.chem.purdue.edu/gchelp/howtosolveit/Solutions/osmoticpressure.html