Desk:
Chem 36.1
TA:
10/11/05
Experiment 2—Distillation and Boiling Points
I. Introduction
Distillation is a common method used to purify and/or separate liquids by means of
boiling. The process of boiling allows a liquid to enter the vapor phase and ultimately leave the
solution. This concept also directs the boiling of separate liquids in the same solution, as a
solution with a lower boiling point will enter the gas phase and evaporate first and the rest will
follow according to their specific boiling points. Condensation of these vapors, if distilled
correctly, will result in an isolated, purified compound.
Distillation itself is broken down into two major categories, simple distillation and
fractional distillation. Simple distillation is most effective in isolating compounds that have a
boiling point difference of greater than 75°C. In this style of distillation, the sample is simply
heated to its boiling point and the vapors are allowed to condense. The relatively large difference
in boiling points allows the solution with a lower boiling point to distill in order to isolate it with
little risk of impurities. Fractional distillation is most useful in isolating compounds with similar
boiling points that are generally less than 75°C, as the fractioning column functions as a location
for the isolation and separation to occur. In this form of distillation, several evaporations occur to
separate whatever compounds may exist in solution and the substances are isolated separately.
Four separate experiments were executed regarding simple and fractional distillation of a
cyclohexane-toluene mixture as well as an ethanol-water mixture. Within each experiment, the
temperature of the vapor was recorded according to the amount of distillate accumulated in order
to show the differences between simple and fractional distillation. The following procedure in
