The following diagram shows a close-up view of the vapor pressure curves for a pure solvent and a solution containing a nonvolatile solute dissolved in this solvent.
-Which curve is the solvent and what happens to the boiling point when the solute is dissolved in the solvent?
A)Curve (a)is the solvent and the boiling point decreases.
B)Curve (a)is the solvent and the boiling point increases.
C)Curve (b)is the solvent and the boiling point decreases.
D)Curve (b)is the solvent and the boiling point increases.

Question

The following diagram shows a close-up view of the vapor pressure curves for a pure solvent and a solution containing a nonvolatile solute dissolved in this solvent. 
-Which curve is the solvent and what happens to the boiling point when the solute is dissolved in the solvent?
A)Curve (a)is the solvent and the boiling point decreases. 
B)Curve (a)is the solvent and the boiling point increases. 
C)Curve (b)is the solvent and the boiling point decreases. 
D)Curve (b)is the solvent and the boiling point increases.

Quizplus · Accepted Answer

Curve (a) represents the pure solvent and curve (b) represents the solution containing a solute. When a nonvolatile solute is dissolved in the solvent, the vapor pressure of the solution decreases as compared to the pure solvent. This results in an increase in the boiling point of the solution. Therefore, the correct option is B, where curve (a) is the solvent and the boiling point increases when the solute is dissolved in it.

The Following Diagram Shows a Close-Up View of the Vapor