Colligative Properties of Solutions Ch. 15.3

Definition of Colligative Properties The physical properties of solutions that are affected by the number of particles but not the identity of dissolved solute particles

Electrolytes ionic compounds conduct electric current when dissolved in water ionic compounds conduct electric current when dissolved in water conduct electric current conduct electric current most molecular compounds do not conduct electric current when dissolved in water ex. NaCl  Na + + Cl -, so double the amount of particles in the solution

Vapor Pressure Lowering pressure exerted in a closed container that have escaped the liquid’s surface and entered gaseous state adding a solute that won’t become a gas easily lowers solvent’s vapor pressure when there is a higher number of solute particles in solution, the vapor pressure is lower because there is a mix of solute and solvent particles occupying the surface of the solution.

Boiling Point Elevation The temperature difference between a solution’s boiling point and a pure solvent’s boiling point Boiling point is higher in a solution because you are vaporizing the solvent and solute particles, so you need more kinetic energy for it to boil

Freezing Point Depression Difference in temperature between the freezing point of a solution and the freezing point of its pure solvent Solute particles interfere with the attractive forces between solvent particles, so the freezing point is lower than that of the pure solvent

Osmosis and Osmotic Pressure Diffusion of solvent particles across a semi-permeable membrane from an area of higher solvent concentration to an area of lower solvent concentration Osmosis Intro Osmosis Intro