At 99, the vapor pressure of water is 733 mm Hg. (a) At standard ...

[acc299]

At 99, the vapor pressure of water is 733 mm Hg.
  (a) At standard atmospheric pressure, what is the vapor pressure of a compound being
  steam-distilled at this temperature?
  (b) If the compound has a molecular weight of 180, how much water is required to distill 1.0 g
  of the compound?

Question 2

Suggest a reason why benzene steam-distills at the rate of 1 g/0.1 g H2O, but nitrobenzene dis
  tills at the rate of 1 g/4 g H2O.

[abctaiwan]

Answer to Question 1

(a) Ptotal = P A + P B
If P A (water) is 733 mm and Ptotal is 760, then P B (the compound being distilled) is (760
733) or 27 mm.
(b) (wtA/wtB) = (P A/P B) x (MWA/MWB)
wtA = 1.0 x (733/27) x (18/180) = 2.7 g of water

Answer to Question 2

Benzene is more volatile (bp 80) than is nitrobenzene (bp 210).