Experiment 5: Simple and Fractional Distillation of a Binary Mixture
A short lab report is required for this experiment.
Here are the sections that need to be included. For sections that are new or different, specific instructions are included.
Names:
Date:
Title:
Purpose: An unknown binary liquid mixture will be purified by simple and fractional distillation as a comparison of the technique’s effectiveness. Success will be measured by the accuracy of the binary mixture identification and percent composition. This identification will be made based on the IR and refractive index analyses of the two distillations.
Physical Properties: (Fill in the BP and Refractive index values).
Chemical / Structure / Formula / MW (g/mol) / BP (°C) / RefractiveIndex (nD20)
n-butyl acetate / C6H12O2 / 116.16
Ethanol (absolute) / C2H6O / 46.04
Cyclohexane / C6H12 / 84.16
Toluene / C7H8 / 92.14
Acetone / C3H6O / 58.08
tert-Butyl alcohol / C4H10O / 74.12
heptane / C7H16 / 100.20
Ethyl benzene / C8H10 / 106.16
References: (Fill in the second reference with your source for the physical property data).
1. CHM 235 Spring 2011 Lab Manual from Dr. Halligan titled “Experiment 4: Simple and Fractional Distillation of a Binary Mixture,” pp. 45-55.
2.
Diagrams: Cut these out from the back of the lab manual and tape them to your report.
Experimental Procedure: (Not required for the Short report).
Data: (All graphs must be computer generated. I recommend getting them started before lab. You and your lab partner can use the same graphs in lab and just print 2 copies of each).
1. Create a Temperature and Volume table like the one below for both Simple and Fractional Distillation. You can cut out both tables on the next two pages and attach them to your notebook to record you and your partner’s data.
Simple Distillation
1 / 19
2 / 20
3 / 21
4 / 22
5 / 23
6 / 24
7 / 25
8 / 26
9 / 27
10 / 28
11 / 29
12 / 30
13 / 31
14 / 32
15 / 33
16 / 34
17 / 35
18 / 36
Fractional Distillation
1 / 19
2 / 20
3 / 21
4 / 22
5 / 23
6 / 24
7 / 25
8 / 26
9 / 27
10 / 28
11 / 29
12 / 30
13 / 31
14 / 32
15 / 33
16 / 34
17 / 35
18 / 36
2. Construct a graph of Temperature vs. Volume of Distillate for the Simple and Fractional distillations. (See Fig. 5.8). Answer the question: What should this graph look like if the separation worked well?
3. Construct a graph of Temperature vs. % Composition (See Figure 5.1) Your ellipse will go from the lower bp component on the left side of the graph to the higher bp component on the right side of the graph. (Draw the ellipse “freehand”). Draw in the dashed lines at the 50:50 mole % composition. Answer the question: What is the bp of the 50:50 mole % solution?
4. Obtain IR spectra of the starting mixture from your lab instructor; then run IRs for compound #1 and compound #2 from your distillation. Label the key absorptions for the two IR spectra you collected for compounds 1 and 2. Draw the structure of the proposed compounds on the appropriate IR spectra.
5. Measure the refractive index of your original mixture (not compounds 1 and 2). Construct a graph of refractive index vs. % composition (Figure 5.7). Determine the % composition of your original binary mixture.
Possible Binary Mixtures:
1. n-butyl acetate and absolute ethanol
2. cyclohexane and toluene
3. acetone and t-butyl alcohol
4. water and t-butyl alcohol
Possible Ratios of the Binary Mixtures: 20:80, 30:70, 40:60, 50:50, 60:40, 70:30 or 80:20
Post-Lab Questions
1. Was the separation of the mixture successful for your distillation? Explain why or why not using your IR data.