CHEM 3760 Orgo I, F14 (Lab #4)
(TECH 704. Distillation)
PRELAB
(PreLab is due before entering the lab.)
Every student has to prepare for each experiment by answering the Pre-Laboratory Assignment,
which will be due prior to the lab. You may use this sheet to practice your answers, however, all
questions / assignments have to be copied and then answered into your Laboratory Notebook,
from which you will hand in the duplicate sheets to the lab TA.
IMPORTANT: You need to complete the PreLab section as well as Section I of the Lab Report
Instructions (see below).
NOTE: You will be performing a macroscale simple or fractional distillation. Please read and be
familiar with the entire procedure, p. 63-72 before coming to lab.
1) (1 pts) Distillation separates two or more compounds based on their differences in _____________________.
2) (4 pts) Give the structure, molecular formula, molecular weight and boiling point of cyclohexane and toluene
each.
3) (2 pts) Cyclohexane is ________________________ and __________________________.
Toluene is ________________________ and __________________________.
4) (1 pts) When two liquids form a homogenous solution they are said to be _____________________.
5) (3 pts) the vapors produced during a distillation move into a water-cooled _____________________.
The vapors ____________________ to a liquid, which is also called a __________________________.
6) (2 pts) The macroscale apparatus for a simple distillation is shown in Figure ______ on page ______.
7) (1 pts) The macroscale apparatus for a fractional distillation is shown in Figure ______.
8) (1 pt) The thermocouple of the simple distillation is set to ________ at the beginning.
9) (1 pt) The thermocouple of the fractional distillation is set to ________ at the beginning.
10) (4 pts) During the simple and fractional macroscale distillation a _____ mL round-bottomed flask is used to
heat the mixture, which measures ______ mL.
11) (4 pts) It is important to place at least two __________________________ in the flask that is being
heated and to never heat a __________________ system.
12) (1 pts) One should never add boiling chips to a ______________________ liquid.
CHEM 3760 Orgo I, F14 (Lab #4)
(TECH 704: Distillation)
LAB REPORT INSTRUCTIONS
Carefully read all instructions and complete Section I on page 2 before you come to the lab.
Experimental Notes:
1. Time is of the essence. It is important for you to be well prepared to complete this week’s lab in
the allotted time. Pay close attention to the volume and temperature modifications.
2. Read and be familiar with the descriptions in the lab manual.
3. Use special care when using this fragile and expensive distillation glassware.
4. You will do the macroscale distillation (simple or fractional). Your TA will assign you to a simple or
fractional distillation.
5. You will use 15 mL of the cyclohexane / toluene mixture (not 50 mL, see p. 71 or 72) in a 50 mL roundbottom flast (not 100 mL flask).
6. For the simple distillation, begin with a digital settting of 135o C.
7. For the fractional distillation, begin with a digital setting of 150o C and raise it to 160o C after 20 min.
8. Ensure that the thermocouple is plugged in and in contact with the heating block.
9. Use a 50 mL round-bottom insert.
10. There is no need for insulation.
11. Work in pairs of TWO.
12. Each pair will generate 1 distillation curve (see Fig. 6) and 2 GC printouts. Make / print two copies of
each and exchange your data with a pair of the other group. In total you will analyze 2 distillation curves
and 4 GC printouts to assess both, a “simple” and a “fractional” distillation.
13. Please follow all safety precautions and do not begin your distillation until your TA has confirmed
that your setup is correct and safe.
14. You will use gas chromatography (GC) to determine the effectiveness of the separation. Follow careful
instructions regarding the use of the GC instrument. You will not measure refractive index in this
experiment. The following website has a useful overview of gas chromatography:
http://antoine.frostburg.edu/chem/senese/101/matter/chromatography.shtml
Lab Report Notes
(written in your lab notebook, 50 pts total)
You may work with a lab partner for the in-lab portion. The lab report is due at the beginning of the next lab session and it
needs to reflect the student’s own work, no group work for lab report entries.
Print clearly in your lab notebook so that the carbon copies are legible. Label everything you hand in the
duplicate pages with your name, date, and experiment number.
Section I Introduction (prepare this section before coming to the lab, 8 pts)
(1 pt)
Date and Title of Experiment
(1 pt)
Objective
Give the structure, molecular weight and boiling point of toluene and cyclohexane.
(2 pts)
List all hazardous compounds
(4 pts)
Provide a “Bulleted Outline” for the procedure (in your own words, see posted example online).
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Section II
Observations and calculations (data recorded during the lab, 23 pts)
1. (4 pts) Note any observations you make about the experiment in the data/observations portion of
your bulleted procedure outline.
2. (4 pts) Record the temperature at which the first drop of distillate is collected and after every ~ 2
mL of distillate.
3. (2 pts) Obtain a gas chromatogram of your first and last fraction. Label the printout with your
name, date, and experiment title. (If there is a line at the instrument proceed to the next task(s)
and return to #3 at a later time.)
4.
(6 pts) Prepare a plot of temperature on the y-axis versus total volume of distillate on the x-axis
(see Fig. 6 in the laboratory manual). Draw a smooth curve through the data points.
5. Distillation composition.
LIST TYPE (simple or fractional)
a) (4 pts) Using Figure 1, estimate the composition of the initial and final samples of distillate
(fractions).
b) (4 pts) How does this compare with the relative ratios of cyclohexane and toluene observed
in your GC chromatogram?
Section III
Results and Discussion (analysis after the experiment is completed, 17 pts)
6. What is the purpose of using boiling chips in the distillation?
7. Distillation analysis.
a) (8 pts) List the retention time and percent area for each component in the 4 GC
chromatograms.
b) (3 pts) Discuss how effective the simple distillation was.
c) (3 pts) Discuss how effective the fractional distillation was.
d) (1 pts) How could the distillation be improved?
e) (2 pts) What are the requirements for carrying out a successful distillation in general?
Describe a best-case scenario.
Section IV
Conclusions (2 pts)
List two new things you learned in doing this experiment or something that you now understand
better than before you did the lab. Explain.
_____________________________
Sign & date your lab report
The lab report is due at the beginning of the next lab session and it needs to reflect the student’s own work, no
group work for lab report entries.
Print clearly in your lab notebook so that the carbon copies are legible. Label everything you hand in the
duplicate pages with your name, date, and experiment number.