Skill 16.1 Analyzing the colligative properties of solutions

A colligative property is a physical property of a solution that depends on the number of solute particles present in solution and usually not on the identity of the solutes involved. 

Vapor pressure lowering, boiling point elevation, freezing point lowering 

After a nonvolatile solute is added to a liquid solvent, a smaller fraction of the molecules at the liquid-gas interface are now volatile - 

This imbalance drives equilibrium away from the vapor phase and into the liquid phase and lowers the 

It follows from a lowered vapor pressure that a higher temperature is required to achieve a vapor pressure equal to the external pressure over the liquid. Thus the boiling point is raised by an amount proportional to the number of solute particles present. 

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