The efficiency of each experiment was found by determining the percent yield of extraction, the percent yield of sublimation, and the total percent yield of caffeine. The percent yields calculated help determine the amount of caffeine recovered, which was the efficiency of this experiment.2 The first part of the experiment required the use of both solid-liquid and liquid-liquid separation in order to extract caffeine from the tea bags. The tea bad was first brewed and filtered. After brewing and filtering, the caffeine was extracted by using a separatory funnel. Through the separtory funnel, a layer of organic layer formed. This layer was the caffeine sample. In order to test the purity of the organic layer, the procedures for thin layer chromatography
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The resulting percent yield of sublimation was 3.48% (% yield=0.3/8.619×100%). The percent yield for sublimation was also not ideal because it was very low. The low percentage could be due to some of the crude caffeine getting stuck to the sides of the flask because the crude caffeine may not have been exposed to enough heat in order to sublime. While trying to remove the “cold finger” from the flask, some of the crystals could have been scraped off by the side of the flask. Another factor to the low percentage could be that some of the product was lost while trying to scrape it off the “cold finger” onto a watch …show more content…
The total percent yield was calculated using the following formula:
Total Percent Yield=(mass of sublimed caffeine)/(total mass of caffeine)×100%
The total percent yield turned out to be 0.55%. The percent yield calculated determined the efficiency of purifying and recovering the caffeine in tea. In order to further determine the purity of the caffeine, the melting point was taken. The literature value of the meting point range for caffeine is 235°C-238°C, while the melting point range of caffeine was found to be 232.7°C-235.1°C. The difference in melting point ranges demonstrates that the sample of caffeine contained impurities. Such impurities were marked as brown specs in the sample, which was white. The three low percent yields and the difference in Rf values resulted from the existence of such impurities.
The resulting percent yield of sublimation was 3.48% (% yield=0.3/8.619×100%). The percent yield for sublimation was also not ideal because it was very low. The low percentage could be due to some of the crude caffeine getting stuck to the sides of the flask because the crude caffeine may not have been exposed to enough heat in order to sublime. While trying to remove the “cold finger” from the flask, some of the crystals could have been scraped off by the side of the flask. Another factor to the low percentage could be that some of the product was lost while trying to scrape it off the “cold finger” onto a watch …show more content…
The total percent yield was calculated using the following formula:
Total Percent Yield=(mass of sublimed caffeine)/(total mass of caffeine)×100%
The total percent yield turned out to be 0.55%. The percent yield calculated determined the efficiency of purifying and recovering the caffeine in tea. In order to further determine the purity of the caffeine, the melting point was taken. The literature value of the meting point range for caffeine is 235°C-238°C, while the melting point range of caffeine was found to be 232.7°C-235.1°C. The difference in melting point ranges demonstrates that the sample of caffeine contained impurities. Such impurities were marked as brown specs in the sample, which was white. The three low percent yields and the difference in Rf values resulted from the existence of such impurities.