Aniline (MW93 g/mol) co-distills with water 98.2 C. The vapor pressure of water at 98.2 C is 717 mmHg. You need to isolate 10 g of aniline. What is the minimum volume of water required to isolate 10 g of aniline in a steam distillation at 760 mmHg?

Answer 1

With A = mass of aniline and W = mass H2O, pA = partial pressure aniline and pW = partial pressure of H2O, then

mass A/mass W = (pA*molar mass A)/pW x molar mass W)
Plug in and solve for mass W.
For pA you will want 760-43 since the pA + pW = 760 at the boiling point. mass A = 10g and solve for mass W. pW = 717 in the problem.