Abstract This experiment aimed to separate and calculate in percentage the alcohol content of a commercial alcoholic beverage by means of fractional distillation. Twenty milliliters of rum, with a proof of 72, and 36% alcohol content, underwent fractional distillation. An amount of 0. 5 ml of distillate was collected in each test tube until the temperature reached 100. The volume of distillate collected was 15 ml, with an ethanol volume of 14 ml, giving a percentage ethanol of 70%.
The large margin of error may have been caused by the inaccurate test tube calibration, tightly wrapped aluminum foil in the fractionating column, or the inconstant and fast distillation rate.
Keywords: ethanol/ethyl alcohol, alcoholic fermentation, distillation, boiling point Introduction Alcoholic beverages play an important part in daily life. Moderate consumption in a social environment is seen as a benefit for both body and soul. There is a great variety of alcoholic beverages for people to enjoy, something to suit almost everyone for almost every occasion (Buglass, 2011).
However, despite having different types of alcoholic beverages, they all share a common base, ethanol or ethyl alcohol, an intoxicating psychoactive drug and the main alcohol component found in alcoholic beverages.
Ethanol is developed naturally as a by-product of fermentation, a process wherein microorganisms consume sugars that are present. Compared to other alcohols, such as methanol, ethylene glycol, ethanol is non-toxic to humans (Booley, 2000).
The foundation of all alcoholic beverages is fermentation, more specifically, alcoholic fermentation. As previously mentioned, this is a process wherein microorganisms convert sugars to carbon dioxide and ethanol, recovering less of the energy stored in the substrate molecules. The sugar may come from different food substances depending on the alcoholic beverage. In wine, sugar comes from grapes; in rum, sugar comes from sugarcane; in beer, sugar comes from barley; and in vodka sugar comes from potatoes.
Different kinds of fungi and microorganisms are able to promote conversion of sugar to ethanol, however these fungi are often able to give certain qualities on beverages by producing characteristic flavors, and thus contributing to the vast diversity of alcoholic beverages. However, fermentation caused by fungi or bacteria can bring undesirable influences on the aroma and flavor of the beverages, however these are usually suppressed in favor of the action of desirable microorganisms by the use of antiseptics and preservatives (Buglass, 2011).
Alcoholic beverages contain different amounts of ethanol. Beer has an estimated amount of 6% ethanol, wine has 15% ethanol, and some hard alcoholic beverages have as high as 60% ethanol. The percentage of ethanol in an alcoholic beverage is referred to as proof. Alcohol proof is twice the alcohol content or percentage (Booley, 2000). Alcohols affect living organisms profoundly, due to the fact that they act as lipid solvents. Alcohols ability to dissolve lipids out of the cell membrane allows them to penetrate rapidly into cells, destroying cell structure, and thereby killing the cell.
Thus is the reason why the moment an alcoholic beverage enters the body it is easily absorbed by the walls of the stomach, reaching the brain in a matter of minutes (Whitney & Roles, 2008). Those who consume excessive amounts of alcoholic beverages and fail to take care of the nutritional and physical needs of the body may face a wide range of organ system disorders such as ulcer, inflammation of the pancreas, and liver cirrhosis; blackouts, hallucinations, and extreme tremors may also be experienced if the central and peripheral nervous systems are damaged (Nordegren, 2002).
Distillation is the oldest method used for separating liquid mixtures. Distillation uses the principle that different liquids have different boiling points, and when a liquid mixture is heated, the liquid with the lower/lowest boiling point evaporates first. The said vapor is routed through a condenser through which the vapor is cooled and causes it to condense to liquid, the liquid collected. As the liquid mixture continues to be heated, most or all of the lower boiling point liquid is driven off leaving the higher boiling liquid/s as residue (Thompson, 2008).
At the end of the experiment, it is expected that the students separate and calculate in percentage the alcohol content of a commercial alcoholic beverage by distillation process; and compare the efficiency of simple and fractional distillation techniques. Results and discussion Distillation is a commonly used method for purifying liquids and separating mixtures of liquids into their individual components (Thompson, 2008). When heating a liquid mixture, some molecules of a liquid possess energy enough for them to escape into vapor, and when these vapor molecules are cooled, they will return to liquid.
This vaporization-condensation step is known as simple distillation (Ramsden, 1994). Each time a distillation process is run, materials are lost. Some evaporate into the air and some are left behind, stuck to the apparatus. After doing three separate simple distillations, so much material has already been lost. Aside from obtaining pure compounds, there is also a need to attain high yields, with little loss. A method exists for carrying out several simple distillations in one apparatus, thereby resulting in smaller losses. This method is called fractional distillation (Ramsden, 1994).
The difference between the apparatus used for simple and the apparatus used for fractional distillation is the presence of a fractionating column in fractional distillation. In a distillation, liquid is converted to vapor by heating and the vapor is then condensed back to liquid by cooling. In a simple distillation set-up this step is done one time. However, in a fractional distillation set-up, as the vapor ascends the column, it encounters a cooler area and condenses. The hot ascending vapors vaporizes the liquid and the vapor travels further up the column, where it encounters a cooler area and condenses.
Hot ascending vapors vaporizes the liquid and it travels a bit further. Each vaporization-condensation cycle is equivalent to a simple distillation so by the time the vapor reaches the top of the column, it has undergone several simple distillations, and has thus undergone further purification than in the simple distillation apparatus. Because it was done in a single apparatus, much less material is lost and the yield is greater than if several separate simple distillations had been done (Ebbing & Gammon, 2011).
Rum is made of different components, namely water, and ethanol, which is a by-product of the sugar from sugarcane or molasses. The boiling point of ethanol is 78. 37°C, while the boiling point of water is 99. 98°C; this being said ethanol will vaporize and will produce a distillate of ethanol. When rum underwent fractional distillation, it produced the following results. Table 1. Volume, temperature and flammability of ethanol during fractional distillation TEST TUBE| VOLUME(ml)| TEMPERATURE (°C)| FLAMMABILITY| 1| 0| 71| | 1| 0. 5| 73| | 2| 1. 0| 78| | 3| 1. 5| 78| | 4| 2.
0| 79| | 5| 2. 5| 79| | 6| 3. 0| 79| | 7| 3. 5| 79| | 8| 4. 0| 79| | 9| 4. 5| 79| | 10| 5. 0| 80| | 11| 5. 5| 80| | 12| 6. 0| 80| | 13| 6. 5| 80| | 14| 7. 0| 80| | 15| 7. 5| 80| | 16| 8. 0| 80| | 17| 8. 5| 80| | 18| 9. 0| 81| | 19| 9. 5| 82| | 20| 10. 0| 83| | 21| 10. 5| 83| | 22| 11. 0| 83| | 23| 11. 5| 85| | 24| 12. 0| 85| | 25| 12. 5| 90| | 26| 13. 0| 94| | 27| 13. 5| 96| | 28| 14. 0| 96| | 29| 14. 5| 98| | 30| 15. 0| 98| | Figure 1. Plotted line graph of the recorded volume and temperature of the distillate As seen in table 1, the volume of ethanol retrieved is 14.
0 ml. Only 14 ml of the 15 ml distillate collected contained ethanol for only the first 28 test tubes tested positive for the flammability test. With this information, the percent ethanol (%ethanol) was computed using the following equation: % ethanol= volume of ethanolvolume of sample ? 100 % ethanol = 14. 0 ml20 ml? 100=70% The percent loss (%loss) was also computed, using the following equation: % loss= volume of sample-(volume of distillate+volume of ethanol)volume of sample ? 100 % loss= 20 ml-(15 ml+6 ml)20 ml ? 100=5. 0%
As for figure 1, it can be concluded that as temperature increases, the volume of distillate also increases. This is due to the fact that the boiling point of ethanol is 78. 37°C, and as the temperature increases, the vapor pressure also increases. Consequently, as vapor pressure increases vaporization of the liquid would accelerate, for vapor pressure is greater than that of the different external forces. Also, there are two boiling point plateaus present in figure 1. The first would be from 0 ml to 11. 5 ml. It can be inferred that the relatively stable temperature from 0 ml to 11.
5 ml shows that ethanol is distilling at that moment. At 12 ml however, there was an increase in temperature and the second plateau is seen, from 12 ml to 15 ml. It can be inferred that the relatively stable temperature from 12 ml to 15 ml is the distillation of a less pure form of ethanol, if not an entirely different component of rum. The alcoholic beverage, Tanduay White Premium Rhum has a proof of 72, and as stated in the introduction, alcohol proof is twice its alcohol percentage. Thus, the %ethanol should be estimated at 36%. There are several factors that may brought this large margin of error.
First, the test tubes used were not properly calibrated, and not uniformly. This being said, some test tubes may contain more or less than the required 0. 5 ml. Secondly, the aluminum foil placed in the fractionating column might have been tightly wrapped and thus failed to provide the necessary heat to distill the material through the apparatus. And lastly, the distillation rate was fast, and it was not kept constant and slow. If the distillation rate is too rapid, the measured boiling point is likely to be inaccurate and the purity of the distillate will be compromised.
In conclusion, fractional distillation is more effective than simple distillation because in fractional distillation, less material is lost and the yield is greater than if several separate simple distillations had been done. Although proper technique should be exercised at all times to ensure the accuracy of the results. Experimental methodology A fractional distillation set-up was prepared. Twenty milliliters of Tanduay White Premium Rhum and 2 pieces of boiling chips were placed inside the pear shaped distilling flask.
The flask was heated with a Bunsen burner, the flame was constantly rotated around the flask. Distillate of 0. 5 ml was collected in separate, numbered, dry test tubes; while the temperature was recorded with each fraction that was collected. The distillation was stopped once the temperature reached 100°C. The set-up was cooled, and the remaining liquid in the distilling flask was transferred into a graduated cylinder, and the volume was recorded. The graph of the temperature reading versus volume of distillate was plotted.
The %ethanol and %loss were calculated. References Booley, T. Alcohol and your liver: The incredibly disgusting story; The Rosen Publishing Group, Inc. : New York, USA, 2000; pp. 8-10. Buglass, A. (Ed. ). Handbook of alcoholic beverages: Technical, analytical, and nutritional aspects; John Wiley and Sons, Ltd. , Publication:USA, 2011; pp. 63-95. Ebbing, D. & Gammon, S. General chemistry (9th ed. ); Brooks/Cole, Cengage Learning: USA, 2011; pp. 496-499 Nordegren, T.
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