Answer to Question #173918 in General Chemistry for Agafe

Question

30.0 ml of pentane (C5H12, density= 0.626 g/ml, v. p= 511 torr) and 45.0 ml of hexane (C6H14, density= 0.655 g/ml, v.p= 150 torr) are mixed at 25.0 Celsius to form an ideal solution

A. Calculate the vapor pressure of this solution

B. Calculate the composition (in mole fractions) of the vapor in contact with this solution

Answer 1

a) 307.034tort

b)Pentane=0.724

Hexane =0.276

The substance with the higher vapor pressure (because of the weaker intermolecular forces) is present in the vapor to a larger mole fraction than it is present in the solution.