Isolation of Caffeine from Tea
Essay by Kill009 • July 18, 2011 • Essay • 382 Words (2 Pages) • 2,176 Views
Isolation of Caffeine from Tea
Purpose- The purpose of this experiment is to isolate caffeine from tea leaves. The caffeine will be isolated by using different techniques such as extraction, drying, and evaporation. Also to determine how pure the final product will be.
Experimental- The experiment began with the tea solution. A tea bag was placed into 20 ml of heated water in a 50 ml beaker on the hot plate. The bag was placed in for 15 minutes and was gently pushed down so that the entire bag was covered with water. The tea solution was then transferred equally into two centrifuge tubes. The tubes were then capped and gently shaken then vented to release pressure. The tubes were then centrifuged for about 3 minutes. This produced a separation in the centrifuge tube. The bottom organic layer was then removed from each centrifuge tube by a Pasteur pipet. This organic material was placed into a clean test tube. This process was then repeated by adding 3 ml of methylene chloride to the solution left over in the centrifuge tube, shaking it then extracting more organic material. All the organic material was placed into one test tube. Sodium sulfate was then added to the organic material, this was left to sit for about 10 minutes with occasional stirring. The solution was then transferred to a preweighed flask, without any of the drying reagent. The flask was then placed in a hot water bath for the evaporation process. The solution evaporated and left only the crude caffeine. The flask was then weighed again in order to find the weight of the caffeine. The melting point was then found using the crude caffeine.
Results- The melting point of the final substance was found to be 225 degrees Celsius. The % recovery was found to be 2.6%. (Please see appendix for calculations)
Discussion- The experiment was successful. The % recovery was 2.6% which was very good indicating that a nearly pure sample of caffeine was formed. Also the melting of the substance was 225 degrees Celsius which is only 11 degrees off from the melting point of pure caffeine which is 236 degrees Celsius.
Conclusion- In conclusion the experiment was a success. The sample was close to pure as indicated by the results. The % recovery was only 2.6% which
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