Question

Distillation is a method of purification based on successive separations and recondensations of vapor above a solution.

A. The vapor pressure of carbon tetrachloride, CCl4, is 0.354 atm and the vapor pressure of chloroform, CHCl3, is 0.526 atm at 316 K. A solution is prepared from equal masses of these two compounds at this temperature. The mole fraction of chloroform in the vapor above this solution is χCHCl3 = 0.657. If the vapor above the original solution is condensed and isolated into a separate flask, the vapor pressure of chloroform above this new solution is 0.346 atm.
Calculate the mole fraction of chloroform in the vapor above a solution obtained by three successive separations and condensations of the vapors above the original solution of carbon tetrachloride and chloroform.
χCHCl3=
B. Show how this result explains the use of distillation as a separation method.

Answer 1

The vapor pressure of carbon tetrachloride, CCl4, is 0.354 atm,

and the vapor pressure of chloroform, CHCl3, is 0.526 atm at

316 K. A solution is prepared from equal masses of these two

compounds at this temperature. Calculate the mole fraction of

the chloroform in the vapor above the solution. If the vapor

above the original solution is condensed and isolated into a

separate flask, what would the vapor pressure of chloroform be

above this new solution?

ANSWER

0.346 atmatm

Chapter 13

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Chemistry Structure and Properties

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Video Transcript

problem. 1 13 asks what the, um the mole fraction of chloroform is if equal masses of carbon tetrachloride and core former mixed together. And then it asks you to condense the vapor above such a solution and figure out what the pressure of core form is above that new solution. So the problem gives you that the vapor pressure of pure carbon tetrachloride is 0.354 atmospheres, and the vapor pressure of pure chloroform is 0.5 to 6 atmospheres. Both of these at 316