[dirac23]

Hi all,

I'm sort of new on here, but i have a quick question re: boiling point composition diagrams of temperature vs. mole fraction of say Xa (for two compounds acid and water). If the initial concentration is given (Xa=.70), how would i go about determining the initial liquid isolated in the fractional distillation of a solution with this initial concentration?  My thought was that i would find Xa=.70 on the x-axis  and go up until i hit the lowest curve and then go over (horizontally) until i hit the second curve (the vapor curve). From what i understand, the composition of the initial liquid that's isolated has to be the same as the composition of the vapor above the solution at this concentration.