Pooja Dutta
ID #: 15132955
CHEM 262
Section: 5BD
Separating Cyclohexane and Toluene by Distillation
The objective of this lab was to separate two miscible liquids with varying boiling points, toluene and cyclohexane, through fractional distillation. This lab also required analyzing the extent of separation to draw conclusions about the nature of the distillation.
Physical Properties
Name of Compound Molecular Formula Molecular
Structure Molecular Weight (g/mol)
84.16 Boiling Point (C) State of Matter
Cyclohexane C6H12
80.7 Clear Liquid, Chloroform-like odor
Toluene C7H8
154.21 110.6 Clear liquid
Compound Hazard
Cyclohexane -May cause irritation upon contact with skin or eyes
-May cause irritation upon inhalation or ingestion
-May permeate through skin
-May be toxic to kidneys, liver, cardiovascular system, and central nervous system
-Repeated or prolonged exposure may produce target organs damage
Toluene -May cause irritation upon contact with skin or eyes
-May cause irritation upon inhalation or ingestion
-Can permeate through the skin and present hazards
-May be toxic to blood, kidneys, nervous system, liver, brain, and central nervous system
-Repeated or prolonged exposure may produce target organs damage
Procedure and Observations
To begin the fractional distillation, materials for the setup were first gathered. A pot, 100 mL round bottle flask, 50 mL graduated cylinder for the receiver, fraction column, distill head and thermometer with adaptor, condenser, and adaptor for receiver were obtained. A graduated cylinder was used to measure out 25 mL each of cyclohexane and toluene and added together to the round bottle flask, which was placed on the pot and that was connected to an electric heater. Then, two boiling chips were added to the flask. Afterwards, the fractional distillation apparatus was setup as shown in Diagram 1. The water flow was started through the condenser and the mixture was heated to boiling. The condensation line was observed as the more volatile liquid traveled up the fractionating column. Aluminum foil was used to wrap the fractionating column and distilling head to minimize temperature fluctuations. Then, as the liquid passed through the condenser the temperature was recorded when the first drop of distillate was in the receiver. The temperature was recorded every 5 mL of distillate that were collected in the receiver. Once the temperature reached about 100 C, heating was stopped and the amount of distillate was recorded. The heater was turned off to lower the temperature and the flask was cooled to room temperature. Lastly, the amount of liquid in the flask was collected and measured, and then the bench area and hood space were cleaned up.
The mixture of cyclohexane and toluene was a clear liquid with a very strong odor. Once the mixture was boiling, it began to bubble and a clear condensation line could be seen in the fractionating column where the gaseous cyclohexane was rising. Initially, the heater was heated very high and once the first drop fell, the heat was reduced too low. This inconsistent distillation in the beginning affected the establishment of liquid-vapor equilibria. As a result, the cyclohexane stopped dropping into the receiver because the mixture was no longer boiling. More time was needed to repeat the heating process and then once distillate began dropping into the flask again, more caution was made on maintaining a steady, consistent temperature. Once the thermometer head was placed farther towards the bottom of the side arm on the distilling head, the temperature shot up by more than 40 degrees. Both liquids were clear at the conclusion of the distillation.
Volume of Distillate (mL) Temperature (C)
0 28
5 50
10 35
15 84
20 86
25 88
30 96
Table 1: This table shows the corresponding temperatures for the total volume of cyclohexane that was distilled and collected in the receiver.

This graph shows a series of fluctuations in temperature for the corresponding volumes of distillate. The first increase in temperature occurs between the first drop of distillate and the 5 mL that was collected in the flask. Then, when the temperature of the heater was reduced too low, the distillate stopped dropping into the flask and the 35C corresponds to when distillation commenced after the solution boiled again. Afterwards, the thermometer was pushed farther in and the temperature increased dramatically to 84 C. Afterwards, a steady temperature increase and rate of distillation was maintained.

Based on the results of this lab, fractional distillation of cyclohexane from toluene was conducted. Given the lower boiling point of cyclohexane than that for toluene, the more volatile liquid separated as a result of heating of the mixture. This gaseous cyclohexane separated from toluene through multiple distillations in the fractionating column