Experiment 1: Simple and Fractional Distillation

Marc Delvin Quero, Ryan Querubin, Rafaelle Raspado, Aimee Ravelo and Ma. Lourdes Roble

Group 8 2G Medical Technology Organic Chemistry Laboratory

ABSTRACT

The group extracted ethanol from the Vodka sample by fractional distillation. We observed that the sample started to boil at 78°C and the first 0.5 mL distillate was collected when the temperature reading was 87°C. Collection of distillate was stopped when 100°C was reached. A total of 16.5 mL of distillate was collected and the first and the last test tubes containing 0.5 mL of distillate each were tested for flammability. After computing for the percentage ethanol and the percentage loss, the group arrived at 8.33% and 15% respectively.

INTRODUCTION

Distillation deals with a mixture, a solution composed of two or more elements, that when boiled, will cause each element to vaporized at different temperatures. Distillation involves the conversion of a liquid into its vapours (evaporation) upon heating and then cooling the vapours back into the liquid (condensation). Due to the small difference in the boiling points, both liquids form vapours simultaneously. Vapours of the boiling liquid mixture are made to pass through a glass fractionating column. The fractionating column is a simple packed column, packed with glass beads, or it is a specially designed column called the bubble plate column. The vapours of the low volatile liquid (the liquid having a higher boiling point) get condensed in this column and return to the distillation flask. The condensate consisting of the pure, more-volatile component (the compound having lower boiling point) leaves the column from the exit near the top and enters the condenser and gets collected in the receiver. The experiment was conducted to differentiate simple distillation from fractional distillation; to know the efficiency of both kinds of distillation; to extract the ethanol component of Vodka, a kind of alcoholic beverage from the other components of the beverage and to calculate the ethanol content of the said beverage.

EXPERIMENTAL

A. Compound/s Sample Tested

30 mL Vodka

B. Procedure

For the Fractional Distillation

In this experiment, a fractional distillation set-up was prepared as shown in Figure 1. After preparing the set up, 33 test tubes were calibrated down to 0.5 mL and numbered them accordingly. Then the group placed three (3) pieces of boiling stones inside the quick-fit

distilling flask and introduced 30 mL of Vodka. Afterwards, the distilling flask containing the vodka was heated using an alcohol lamp until the solution started to boil. Temperature was recorded when the first drop of distillate was collected. 0.5 mL of distillate were placed in each test tube and the collection of distillate was stopped when the temperature reading was 100°C .

For Flammability Test

The group placed 3-5 drops of distillate from the first test tube in a watch glass and another 3-5 drops of distillate from the last test tube were placed in another watch glass for flammability test.

RESULTS AND DISCUSSION

Figure 1. The Fractional Distillation Set-Up

Ethanol (ethyl alcohol) from the Vodka sample was extracted using fractional distillation. The figure above shows the proper and correct fractional distillation set up. The set up is different from that of simple distillation because of the presence of a fractionating column with packing.

Volume Temperature0.5 871.0 87

1.5 872.0 882.5 883.0 883.5 894.0 894.5 895.0 895.5 896.0 906.5 917.0 927.5 928.0 938.5 939.0 9410.0 9410.5 9511.0 9511.5 9612.0 9612.5 9713.0 9713.5 9814.0 9814.5 9815.0 9915.5 9916.0 9916.5 100

Table 1. The Volume and Temperature

Table 1 shows the progress in temperature of the sample in relation to the increasing volume. From 3.5 mL to 5.5 mL, there was a constant temperature of 89°C which is considered the plateau. The plateau is 2.5 mL. Ethanol has a lower boiling point that water. It is more volatile than water so we expect that ethanol will be the first distillate since ethanol will evaporate first. The first distillate was collected with 87°C temperature reading. And collection was stopped when 100°C was reached totalling the number of distillate to 16.5 mL.

Temperature(°C) vs Volume (mL)

86

88

90

92

94

96

98

100

102

0 5 10 15 20

Figure 2. Temperature vs. Volume Figure 2 shows the relationship between the volume and the temperature during the collection of distillate.

Distillate ResultFirst Distillate FlammableLast Distillate Non-flammable

Table 2. Observations during Flammability Test

Since ethanol is more volatile than water, the first distillate is ethanol. When subjected to flammability test, the first distillate is flammable while the last distillate is non-flammable. This is because the last distillate was collected when 100°C hence it is water.

Distillate ComponentFirst Distillate VodkaLast Distillate Water

Table 3. Component/s of the distillate based on flammability test.

Percentage of Ethanol

% Ethanol = 2.5 mL x 10030 mL

= 8.33 %

Based on Table 1, the plateau is from 3.5 mL to 5.5 mL which is 2.5 mL. Dividing it to the total number of sample and then multiplying the quotient to 100 the resulting percent is 8.33

Percentage Loss

% Loss = 30 mL – (Distillate + Residue) x 100 30 mL = 30 mL – (16.5 mL + 9 mL) x 100

30 mL = 15 %

After performing the experiment, we measured the residue and it is 9 mL. Percentage loss is the result from dividing the difference of the total number of sample used to the sum of the distillate (which is 16.5 mL based on the given date in Table 1) and the residue by the total number of sample again then the quotient is multiplied to 100 to get the %.

REFERENCES

Pavia, D.L., Lampman, G.M. & Kriz, G.S. (2005). Introduction to Organic Chemistry techniques: A small-scale approach (2nd Ed). Pacific Groove, CA. Thomson – Brooks/ Cole

Seader, J. D., and Henley, Ernest J. (1998). Separation Process Principles. New York: Wiley

University of Colorado – Boulder Department of Chemistry and Biochemistry (2003). CU Boulder Organic Chemistry Undergraduate Courses Lab Techniques. Retrieved May 30, 2007 from the University of Colorado website http://orgchem.colorado.edu/hndbksupport/dist/html

University of Santo Tomas Department of Chemistry (2006). Organic Chemistry Laboratory Manual. Manila

Tutor Vistahttp://www.tutorvista.com/content/chemistry/chemistry-iii/organic-compounds/distillation.php