Vapour-liquid equilibrium of a two-component ideal solution of trichloroethene (C2HCl3) and trichloromethane (CHCl3) is established at 25 °C. The mole fraction of CHCl3 in the vapour phase is 1. What is the mass fraction of C2HCl3 in the liquid phase? The vapor pressure of trichloroethene and trichloromethane at 25 °C are:
Pvap, C2HCl3 = 73.0 mmHg
Pvap, CHCl3 = 199.1 mm Hg
I'm confused about this problem, if the mole fraction of one element equals to 1, would not be the mole fraction of another element be 0? Can someone advise me on how to approach this problem?