Pentane (C₅H₁₂) and Hexane (C₆H₁₄) Form an Ideal Solution

Multiple Choice

Pentane (C₅H₁₂) and hexane (C₆H₁₄) form an ideal solution. The vapor pressures of pentane and hexane at 25° C are 511 torr and 150 torr, respectively. The mole fraction of hexane in a pentane-hexane solution is 0.50. Calculate the mole fraction of pentane in the vapor that is in equilibrium at 25°C with this solution.

A) 0.23
B) 0.77
C) 0.89
D) 0.50
E) none of these