Author Question: Predict the boiling points of the following compounds at the pressure indicated. (a) water at 745 ... (Read 22 times)

joblessjake · **on:** Aug 23, 2018

Predict the boiling points of the following compounds at the pressure indicated.
(a) water at 745 mm Hg
(b) dichloromethane (bp 40 at 760 mm) at 737 mm
(c) benzene (bp 80 at 760 mm) at 765 mm

Question 2

A chemist has a small amount of a compound (bp 65) that must be fractionally distilled, yet
the chemist does not want to lose any of the compound to holdup on the column. What can the
chemist do?

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

Answer to Question 1

(a) bp = 100 (0.5/(10 mm x 15 mm) = 99.25, or about 99
(b) 39.85, or about 40
(c) 80.25, or about 80

Answer to Question 2

One way to distill a small amount of compound is to add a chaser, a high-boiling compound
whose vapors will displace the vapors of the desired low-boiling compound. Otherwise, a
smaller fractionation apparatus or a Vigreux column could be used.