Tori Minick
Distillation of a Cyclohexane-Toluene Mixture
Purpose:
Distillation is an important separation/purification technique when one is dealing with a
liquid organic compound. There are two distillations in which we are experimenting with using
Cyclohexane-Toluene. Simple distillation is when the liquid contains a non-volatile impurity and
severs as a purification technique. Fractional distillation is when a mixture of two components
with similar boiling points is boiled. We will be experimenting with these two distillation
processes to determine which works best for Cyclohexane-Toluene
Materials:
 Boiling Chip
 Thermometer
 Ice bath
 A macroscale simple distillation apparatus
 A macroscale fractional distillation apparatus
 Copper Sponge
 Following Chemicals
Chemicals:
Cyclohexane C6H12
Toluene
C6H5CH3
84.16g/mol
92.14g/mol
7℃
-95℃
81℃
111℃
779.00kg/m3 yes
866.90kg/m3 yes
Procedure:
Simple Distillation
 Obtain 30mL of both chemicals and place in a dry 100mL flask with a boiling chip
 Heat till boiling begins
 Adjust the heat until the distillate drops at a drop per second
 Continuously record both temperature and volume of distillate at regular intervals
 After 50mL is collected stop distillation process
 Record barometric pressure, check thermometer one last time, and plot boiling point
versus the volume of distillate.
 Save distillate for fractional distillation
 Allow flask to cool
Fractional Distillation
 Pour 50mL of distillate back into the distilling flask, add new boiling chips
 Allow boiling to begin before turning down heat (heat slowly at first)
 Look for ring of condensate to adjust heat
 Distillation rate at optimum temperature should have a rate no greater than 1mL in 1.52mins
 Record temperature as each mL collects and more once temperature rises abruptly
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Stop when a second constant temperature is reached
Plot distillation curve and record what observations happened in the column
Combined pure fractions
Clean up lab
Pre lab questions
8. As the temperature rises in a closed apparatus the pressure will build up and eventually
explode
9. At a fast distillation the temperature is normally higher, allowing the mixture to evaporate too
quickly for the liquids to separate
10. In a packed fractionating column the surface area is greater allowing more condensations and
distillations
11. A small amount of water may be present and since toluene is insoluble the water is cloudy.
Post Lab Questions
1. Let’s say you are instructed to collect your distillate (condensate) in four separate
containers, ~1 mL in each, during the fractional distillation of 4 mL of a (1:1)
cyclohexane-toluene mixture, and then obtain IR spectra for each fraction. How would
the IR spectrum of the first 1 mL fraction look different from that of the last 1 mL
fraction?
a. As the distillation of the cyclohexane-toluene continues the cyclohexane is the
first of the chemicals to be completely used and then the continuation distillation
of the toluene until that it is completely used. Therefor the spectrum of the first
fraction will contain the combination of the two chemicals and the spectrum for
the last 1mL spectrum will contain only the reading for toluene.
2. You are given a liquid sample and assigned the following task:
a. determine if the sample has non-volatile impurities (dissolved in it)
i. by using the simple distillation if the sample has non-volatile impurities
b. if found to contain such impurities, determine a suitable method for its
purification
i. fractional distillation would be a suitable method for its purification
Observations/Results:
Look at Chart page attached to back
Errors:
For the fractional recordings at one point the temperature dropped due to apparatus being
turned down.