Diethyl ether has a vapor pressure of 400.0 torr at 18°C.When a sample of benzoic acid is dissolved in ether,the vapor pressure of the solution is 342 torr.What is the mole fraction of benzoic acid in the solution?
A)0.0169
B)0.0197
C)0.145
D)0.855
E)None of these choices is correct.

Question

Quizplus · Accepted Answer

Using Raoult's Law:
Ptotal = Xether * Pether + Xbenzoic acid * Pbenzoic acid

Solving for Xbenzoic acid:
Xbenzoic acid = (Ptotal - Xether * Pether) / Pbenzoic acid

Substituting the given values:
Xbenzoic acid = (342 - 0.760 * 400) / 60 = 0.145

Therefore, the mole fraction of benzoic acid in the solution is 0.145, which is choice C.

Diethyl Ether Has a Vapor Pressure of 400