Simple and Fractional Distillation
Authors:
Abion, T.J.J., Aganda, J.C., Alpay, R.F., Berboso, M.J.R., Casuga, J.M.D.
(Group01-2A-BC)

Abstract Distillation is the process of converting a liquid to a vapor, condensing the vapor, and then, collecting the distillate in another container. More about distillation will be discussed in the introduction. This experiment was carried out to differentiate simple from fractional distillation, to separate the components of an alcoholic drink, and to calculate the percentage of ethanol present in an alcoholic beverage. The group is assigned to do simple distillation. The computations performed for this experiment are the percent alcohol and percent loss. Percent alcohol determines the percentage of ethanol found in the beverage, while percent loss ascertains the amount of sample lost while doing the experiment. The experiment follows the distillation process to flammability test. The experiment follows as is in the procedure with some difficulties that will be seen in the latter part.

Introduction
Distillation is the process of purifying compounds by means of separating more volatile substance from non-volatile or less volatile substance. The analysts performed one of the two types of distillation processes- the simple distillation and fractional distillation. In simple distillation, the vapor emerging from the evaporating surface moves uniformly without contacting condensed liquid until they reach the condensing surface. Thus, the composition of the vapor leaving the liquid does not change as it moves from the surface of the liquid to the condenser. It is very suitable for the separation of simple mixtures where the components differ widely in boiling point. While fractional distillation produces more efficient separations than simple distillation. This type of distillation is an equilibrium process in which the composition of the boiling liquid and the distillate is constantly changing as the distillation proceeds (Jackson, Laddad, & Robards, 2004).
In this process, there are two principles involved, Raoult’s Law and Dalton’s Law. Kotz,Townsend & Kotz (2009) stated that Raoult’s Law tells us that the vapor pressure of a solution equals the product of the vapor pressure of the pure solvent and the mole fraction of the solvent. While Dalton’s Law, which is also known as the law of partial pressure, connotes that the pressure of a gas mixture is equal to the sum of the partial pressures of the gas composing it (Cohn & Russel, 2013).
In this experiment, the analysts must attain the following objectives: (1) to differentiate simple from fractional distillation and (2) separate the components of an alcoholic beverage. Lastly, (3) to calculate the percentage of ethanol in a beverage.

Methods

At the start of the experiment the simple distillation set-up was assembled. The group prepared several test tubes and calibrated it down to 0.5 mL mark and then numbered them accordingly. 15 mL of gin were introduced into the distilling flask with boiling stones. The flask was then heated until the gin starts to boil. The temperature was recorded at every first drop after collecting 0.5 mL each of the distillate into the calibrated and numbered test tubes. The group stopped collecting distillate when they already reached a constant temperature. After then, 3-5 drops of the distillate from the first test tube were placed on a watch glass and a lighted match was applied to check on its flammability. The procedure on flammability test was repeated on the distillate from the last test tube.
% alcohol=VethanolVsample×100

% error = Theoretical-Actual% alcoholTheoretical % alcohol

Results and Discussion

The results obtained by the group are as follows: A few minutes after heating the flask and boiling the gin, the first drop of distillate was at a temperature of 73°C. The temperature increased at 81°C in the first drop for the second test tube. The temperature increased slowly but it decreased at the 7th test tube because the group had to fix their thermometer so they stopped boiling the flask for a while. The experiment resumed and the temperature returned to 84°C on the first drop of the 8th test tube. It rose until such time that the temperature has a constant value of 95°C from test tube 15 up to test tube 20 where the group stopped. The group computed the values for the % alcohol, % loss, and % error. The calculation for the % alcohol:

% alcohol=VethanolVsample×100 = 2(0.5)15×100
% alcohol =6.67%
The calculation for % loss:
% loss= Vsample-Vdistillate residueVsample×100 = 15-(7.5+2.4)15×100
% loss=34%
The calculation for % error:
% error = Theoretical-Actual% alcoholTheoretical % alcohol = 40%-6.67%40%
% error=83.33%
The result obtained by the group is that the percent alcohol in their sample of 15 ml gin is 6.67% with a % loss of 34% and a % error of 83.33%. There is another type of error associated with a directly measured quantity, called the reading error. The value of the percent error is large because of the poor technique of the group and their faulty reading. When the distillate started to drop for the first test tube, the reader of the temperature didn’t get to read at once. Because of that, the group had an error at the first reading because the temperature already rose before they could read and record it. It continued to be like that for a while before the group could read the temperature accurately. This caused the large difference between the temperatures of the first few test tubes.
After placing 3-5 drops of the distillate from the first test tube, the group observed that it was still flammable and it showed a bluish flame for few moments, while the distillate from the last test tube did not show any sign of flame. Therefore, we concluded, that the distillate from the last test tube no longer contains ethanol.
References
Books
Cohn, R., & Russel J. (2013). Dalton’s Law. Canada: Book On Demand.
Jackson, P.E., Laddad, P.R., & Robards, K. (2004). Principles and Practice of Modern Chromatographic Methods. London, UK: Elsevier Academic Press.
Kotz, J.C., Townsend, J., & Treichel, P.M. (2009). Chemistry and Chemical Reactivity (Volume 2). Belmont, CA: Thomas Brooks/Cole.
Article
Wolfram Research (2013). Experimental Errors and Error Analysis. Wolfram Mathematica. Retieved July 14, 2013, from http://reference.wolfram.com/applications/eda/ExperimentalErrorsAndErrorAnalysis.html