Author Question: Explain why a vacuum distillation apparatus should be checked for leaks before the material to be ... (Read 30 times)

lracut11 · **on:** Aug 23, 2018

Explain why a vacuum distillation apparatus should be checked for leaks before the material
to be distilled is placed in the flask.

Question 2

At low pressures such as used in vacuum distillation, reducing the pressure by half reduces a
boiling point by about 10. If a compound boils at 180 at 10 mm Hg, what would be its
approximate boiling point at the following pressures?
(a) 15 mm Hg
(b) 2.0 mm Hg

bookworm410 · **Reply #1 on:** Aug 23, 2018

Answer to Question 1

The material to be distilled will itself have vapor pressure. There is also the possibility that the
material to be distilled will contain some residual low-boiling solvent that will provide signifi
cant vapor pressure. Therefore, inability to draw a vacuum may be due to a leak or it may be
due to the vapor presure from the material in the flask. With an empty flask, the inability to
draw a vacuum must be due to a leak.

Answer to Question 2

(a) 185
(b) 156