Extraction Of Caffeine From Tea Leaves Argumentative Essay Example

flask and was drained into a 25 ml flask after each wash. To prevent emulsion, each wash was gently swirled. The cumulative washes were then dried using small portions of Na2SO4 twice in order to eliminate any water.

A suction flask was weighed before adding the CH2Cl2. The CH2Cl2 was poured into the flask, leaving the Na2SO4 behind. A small sample was taken and compared to pure caffeine on a TLC plate. The suction flask with the CH2Cl2 was placed in a low temperature hot water bath with a boiling stick to evaporate the CH2Cl2, leaving only caffeine. The reweighing of the suction flask determined the weight of the extracted caffeine. The flask was then covered with parafilm and the sublimation process was conducted one week later. The Sublimation apparatus consisted of a filtration flask with our caffeine extract and a test tube securely inserted 10-15mm from the bottom of the flask.

The flask was secured with a rubber stopper and parafilm. A pippet bulb was inserted over the arm of the suction flask before placing it in a sand bath with a temperature ranging from 200-220 degrees Celsius. The test tube was initially filled with solid ice and water was periodically replaced with more ice during the sublimation process. As the sublimation occurred, the caffeine extract accumulated as a film on the bottom of the test tube. The process concluded once all the caffeine had been extracted from the flask.

The test tube was taken out and the accumulated caffeine was scraped off and measured in weight. The melting point of the caffeine in its pure form was also determined. In the extraction experiment, 0.12

grams of impure caffeine extract remained in the suction flask. This value may be lower than anticipated due to the presence of emulsion in the seperatory funnel during each wash.

Some of our extract may have been lost during the process. Additionally, a small amount of the solid extract remained on the boiling stick when boiling the CH2Cl2. On the TLC plate, our tea extract and pure caffeine traveled a similar distance. The Co-spot also traveled the same distance as pure caffeine, with both having Rf values of 0.

66. The Rf value for the tea extract was 0.133, possibly indicating impurities and variations in concentration among the spots during sublimation.

003g of pure caffeine was scraped from the test tube. The melting point range of the pure caffeine was tested and found to be 237-239 degrees Celsius. The actual melting point of caffeine is 238. Conclusion The results of the TLC plate showed that the tea extract was very close to the sample of pure caffeine. It was slightly off possibly due to impurities that remained in the tea extract. The caffeine weighed in the flask after the liquid-liquid extracted was 0.

The weight of the caffeine obtained after the sublimation was different from the weight of the original caffeine, likely due to impurities. The extracted caffeine from the sublimation had a melting point of 237-239 degrees Celsius, matching the reported value. The sublimation process resulted in a completely pure extract of caffeine.

Questions

• Why is sodium chloride added to the tea solution before extraction with CH?

Sodium chloride aids in removing water from the organic layer and helps facilitate the transfer of the organic compound into the organic layer.

No, ethanol and water mix together and do not separate into distinct layers. Therefore, a less polar solvent like CH? Cl? is preferred to separate and extract caffeine from water.

• Why is sodium carbonate added to the flask during the brewing step?

Sodium carbonate acts as a base and triggers the formation of a precipitate, allowing solid material to be removed. It takes approximately 8 minutes at a temperature of 25 degrees Celsius for 1.0 g of caffeine to dissolve in 47 mL of water.

The solubility of caffeine differs depending on the solvent used. For example, in 1 mL of chloroform, it has a solubility rate of 86 mL in benzene and 370 mL in diethyl ether. To convert this data into grams per 100mL, calculating the partition coefficient of caffeine between water and each solvent is necessary.