Colligative properties

Vapor pressure lowering

Raoult's Law: P = XP°, where P = vapor pressure of substance in solution, P° = the vapor pressure of the pure substance and X = its mole fraction

Boiling point elevation

deltaTb = kbm, where m = molality = moles solute/kg solvent, and kb is a constant specific to the solvent.

Freezing point depression

deltaTf = -kfm, where m = molality = moles solute/kg solvent, and kf is a constant specific to the solvent.

Osmotic pressure (pi)

piV = nRT; or, dividing both sides by V, pi = MRT, where M = molarity.

 

 

 

 

 

 

 

© R A Paselk

Last modified 24 April 2015