Calculate the χacetone and χcyclohexane in the vapor above the solution. p°acetone = 229.5 torr and p°cyclohexane = 97.6 torr.

First calculate the mole fraction of each substance:

Acetone: 2.88 mol : (2.88 mol + 1.45 mol) = 0.665

Cyclohexane: 1.45 : (2.88 mol + 1.45 mol) = 0.335

Raoult's Law: P (total) = P (acetone) · χ (acetone) + P (cyclohexane) · χ (cyclohexane).

P (total) = 229.5 torr · 0.665 + 97.6 torr · 0.335

P (total) = 185.3 torr

χ for acetone: 229.5 torr · 0.665 : 185.3 torr = 0.823

χ for cyclohexane: 97.6 torr · 0.335 : 185.3 torr = 0.177