When 1 mol of a nonvolatile solvent-nondissociating substance is dissolved in 3 mol of solvent, the ratio of vapor pressure of the solution to that of the pure solvent (at the same temperature) is approximately
A) 2/3.
B) 3/4.
C) 1/4.
D) 1/3.
E) none of these

Question

Quizplus · Accepted Answer

The ratio of the vapor pressure of the solution to that of the pure solvent is given by Raoult's law, which states that the vapor pressure of a solution is directly proportional to the mole fraction of the solvent. In this case, the mole fraction of the solvent is 3/(1+3) = 3/4.

When 1 Mol of a Nonvolatile Solvent-Nondissociating Substance Is Dissolved