A solute added to a solvent raises the boiling point of the solution because
A)the temperature to cause boiling must be great enough to boil not only the solvent but also the solute.
B)the solute particles raise the solvent's vapor pressure,thus requiring a higher temperature to cause boiling.
C)the solute increases the volume of the solution,and an increase in volume requires an increase in the temperature to reach the boiling point (derived from PV = nRT).
D)the solute particles lower the solvent's vapor pressure,thus requiring a higher temperature to cause boiling.
E)two of these explanations are correct.

Question

Quizplus · Accepted Answer

The solute particles lower the solvent's vapor pressure, and according to Raoult's Law, the vapor pressure of the solvent above the solution is proportional to the mole fraction of the solvent particles. Therefore, as the solute particles lower the solvent's vapor pressure, a higher temperature is required to increase the vapor pressure to the atmospheric pressure, i.e., to cause boiling.

A Solute Added to a Solvent Raises the Boiling Point