Osmometers utilizing the vapor-pressure colligative property of solutions are based on what principle?
A)An increase in the concentration of dissolved solutes decreases the vapor pressure generated because of a lack of volatility of the typical solutes.
B)An increase in the concentration of dissolved solutes increases the vapor pressure generated because of a lack of volatility of the typical solutes.
C)An increase in the concentration of dissolved solutes decreases the vapor pressure generated because of an increased volatility of the typical solutes.
D)An increase in the concentration of dissolved solutes increases the vapor pressure generated because of an increased volatility of the typical solutes.

Question

Quizplus · Accepted Answer

In vapor-pressure measurements, the pressure created by volatile molecules (such as solvent molecules) is measured.Generally a solute molecule is not volatile.As the concentration of dissolved solutes increases in a solution, there is a greater chance that solute molecules in the solution will be on the surface of the solution being tested.The increased numbers of nonvolatile molecules on the surface of the solution will decrease the amount of evaporation of the solvent.Thus vapor pressure from the solvent evaporating will be decreased, resulting in vapor-pressure depression.

Osmometers Utilizing the Vapor-Pressure Colligative Property of Solutions Are Based