Colligative Properties

Colligative Property

A property of solutions that depends only upon the number of solute particles, not their identity.

Vapor Pressure Lowering

The decrease in vapor pressure experienced by a solution containing a nonvolatile solute compared to the pure solvent.

Freezing-point Depression

The temperature difference between the freezing point of a solution and that of a pure solvent, caused by adding a solute.

Boiling-point Elevation

The temperature difference between the boiling point of a solution and that of a pure solvent, which occurs when a solute is added.

Nonvolatile Solute

A solute that does not vaporize easily and always lowers the vapor pressure of a solution.

Volatile Substance

A substance that easily evaporates and can increase the vapor pressure when mixed with a solvent.

Ionic Solute

A solute that dissociates into ions in solution, such as NaCl or CaCl2, affecting colligative properties more significantly than covalent solutes.

Covalent Solute

A solute that does not dissociate into ions in solution and generally has a smaller impact on colligative properties.

Molecular Solutes

Solutes that do not form ions in solution; they affect colligative properties less than ionic solutes.

Shell of Solvation Molecules

The layer of solvent molecules that surround a solute particle in a solution.

Example of Freezing-point Depression Calculation

For 1 L water with 1 mol NaCl, Freezing Point Depression = 2 × -1.86°C = -3.72°C.

Real-life example of Boiling Point Elevation

When adding salt to water, the boiling point of the solution increases compared to pure water.