- A colligative property is any property that depends on the concentration of solute particles in a solution but not on their identity. Colligative properties only apply to solutions.
- Raoult's Law
P = mole fraction of solvent x Po
where P is the partial pressure of solvent vapor from a solution,Po is the partial pressure of vapor from pure solvent, and the mole fraction of the solvent is concentration of solvent particles / concentration of all particles in a solution.
(Note: Vapor pressure isthe pressure of a gas that collects above a liquid in a closed container. The gas and the liquid are in dynamic equilibrium.)
DP = mole fraction of solute x Po
In dilute solutions,DTBP= kb x molality of solute particles
where kb is the molal B.P. elevation constant
DTFP= -kf x molality of solute particles
where kf is the molal freezing point depression constant
The osmotic pressure of a solution is the minimumpressure needed to prevent osmosis of pure water across a semipermeable membrane into this solution.
Osmotic pressure= RT [solute particles]