Distillation of Spirit

Distillation of Spirit

Introduction

There are many processes that can be used for separation of a mixture from another liquid or solid and one of them is distillation. Distillation is a widely used method for separating mixtures based on differences in the conditions required to change the phase of components of the mixture. To separate a mixture of liquids, the liquid can be heated to force components, which have different boiling points, into the gas phase. The gas is then condensed back into liquid form and collected. Repeating the process on the collected liquid to improve the purity of the product is called double distillation. Although the term is most commonly applied to liquids, the reverse process can be used to separate gases by liquefying components using changes in temperature and/or pressure¹. Distillation is an important process in petroleum refining, in which petroleum is separated into its useful parts, such as fuel oils and gasoline². It can also be used to separate solid impurities from water and other liquids. Distillation is used for many commercial processes, such as production of distilled water, xylene, alcohol, paraffin, kerosene, and many other liquids¹. The types of distillation include simple distillation, fractional distillation and destructive distillation, wherein, usually, a material is heated so that it decomposes into compounds for collection¹. Since in this experiment we have only used the first two types of distillation mentioned, these will be the only ones that will be further elaborated.

The simple distillation is practiced for a mixture in which the boiling point of the components differ by at least 70oC. It is also followed for the mixtures contaminated with nonvolatile particles (solid or oil) and those that are nearly pure with less than 10 percent contamination. Double distillation is the process of repeating distillation on the collected liquid in order to enhance the purity of the separated compounds⁴.

For those mixtures, in which the volatility of the components is nearly similar or differs by 25oC (at 1 atmosphere pressure), that cannot be separated by simple distillation, fractional distillation is used. Fractional distillation is used whereby the constituents are separated by a fractionating column. In the fractionating column, the plates are arranged and the compound with the least boiling point are collected at the top while those with higher boiling point are present at the bottom. A series of compounds are separated simultaneously one after another. Fractional distillation is used for the alcohol purification and gasoline purification in petroleum refining industries⁴.

After the distillation process, we have collected what we call the distillate that was subjected to calculating its alcohol content, specifically ethanol. Ethanol is sometimes called grain alcohol because it is produced from the fermentation of carbohydrates found in various grains, such as corn, rye and barley. Ethanol is found in beer, wine and other alcoholic beverages. Because it burns in an internal combustion, ethanol is also blended with gasoline to give a mixture called gasohol that is 10% ethanol².

Results and Discussion

The experiment was done by first putting up the set-up of the assigned type of distillation process assigned to the group which is the fractional distillation. When the set-up was done, the liquid sample, The Bar Silver, of 25 mL in volume was now placed in the distilling flask and also two pieces of boiling chips. The flask was heated with the Bunsen burner that was constantly rotated around the flask.

The first drop of the distilled liquid was collected in the first test tube. Its temperature was recorded which was 62oC. When that test tube reached 1 mL, its temperature of 70oC was also recorded. The process had been repeated until the temperature reading on the thermometer reached about 100oC. All of the test tubes used have been calibrated at the 1 mL mark before the experiment. The three test tubes that had the same temperatures at the 1 mL mark, from the temperatures recorded, was distinguished. It was the 3rd, 4th & 5th test tubes that had the same temperature of 80oC. The highest temperature recorded was 97oC. The heating was now stopped since it almost reached 100oC and we let the set-up cool before the remaining liquid was poured into a graduated cylinder to be measured. After the remaining liquid cooled and had been transferred into a graduated cylinder, it measured a volume of 6 mL. The test tubes containing the collected distillates was then subjected to the flammability test. Eight of the eleven test tubes showed a positive result, leaving the other three test tubes showing a negative result.

The percent of ethanol, percent loss and percent error was then calculated. The percent of ethanol was calculated using the volume of the distillate contained in test tubes that was positive in the flammability test; it was a total of 8mL and the total volume of the sample used; it was 25 mL. The percent loss was calculated from the volume of the remaining liquid of 6 mL. Last but not the least, using the value of alcohol content from the sample label, which was 70 proof, and the computed value for ethanol content, the percent error was calculated. The experiment yielded to having 32% ethanol, a 32% loss and a 12% error.

The proof system for specifying the alcohol content of beverages is twice the percent by volume³. Since it was 70 proof, it contained 35% (v/v) alcohol. The (v/v) connotes percent by volume which is a type of percentage unit. It is the volume of solute in a solution divided by the total volume of solution, multiplied by 100 and is used as a concentration unit in situations where the solute and solvent are both liquids or both gases³.

In comparison to the group who did the simple distillation using the same liquid sample, they got 52%