Organic Chemistry Laboratory
This experiment was conducted in order to compare single and multiple extraction of caffeine from dried tea leaves and to calculate the percentage yield of caffeine for both extraction procedures. The group was assigned to do the multiple extraction. Before the extraction proper, the water bath containing the anhydrous sodium carbonate and distilled water was heated. As the sodium carbonate dissolves, tea leaves were added in the mixture and allowed to heat for ten minutes. Upon heating, the solution was extracted three times with the dichloromethane. The mixture resulted into to two layers with the upper layer being the aqueous solution while the lower contained the organic substance. After discarding the upper layer, the organic layer extracts were transferred into the Erlenmeyer flask containing the anhydrous sodium sulfate and was decant on a weighed evaporating dish under the hood. After which, it was evaporated to dryness. The residue was weighed and the percentage yield was calculated. The residue for this experiment weighed 1.75 grams. The percentage yield was computed by getting the quotient of the weight of the residue and the weight of the tea leaves, and multiplying the result to one hundred. The computed percentage yield for this experiment was 17.5%.
Experiment 2 is about extraction. The goals of the experiment are to compare the types of extraction and to compute its corresponding percentage yield. Extractions are a way to separate a desired substance when it is mixed with others. Extractions use two immiscible phases to separate the substance from one phase into the other. Typical lab extractions are of organic compounds out of an aqueous phase and into an organic phase. The distribution of a solute between two phases is an equilibrium condition described by partition theory. In this extraction, tea leaves are boiled in anhydrous sodium carbonate solution to extract the tannins,...
References:  Chemicool. (2013). Extraction. Retrieved July 28, 2013 from <http://www.chemicool.com/definition/extraction.html >
[2 University of Colorado at Boulder, Department of Chemistry and Biochemistry. (2013). Extraction. Retrieved July 28, 2013 from <http://orgchem.colorado.edu/Technique/Procedures/Extraction/Extraction.html>
 Bayquen, A.V., et al. (2009). Laboratory Manual in Organic Chemistry. Q.C., Philippines: C&E Publishing Inc.
Please join StudyMode to read the full document