CHEM 14CLWinter 2004NOTE: Make sure that you look for organization of ideas and not just a copy of the procedure in boxes.Pre-lab Report Guideline for Experiment 7(a) ContinueCHEM 14CL Winter 2004 7(A) Extraction and Purification of Caffeine from Tea Leaves Procedures for experiment 7(A) - see p.76 - 80 (lab manual) Pre-lab Report Guideline for Experiment 7(A) NOTE that ONLY parts 1 and 2 are DUE on 1/27 and 1/28. Part 3 (study questions) is DUE on 1/29 and 1/30 depending on when your section meets. 1. Introduction – list the goal(s) of the experiment and any experimental techniques that will be used during the experiment for purification and/ or identification. 2. Prepare a flow chart of procedures AND show the location of the caffeine throughout each step of the experiment in the flow chart. Make sure you also REFERENCE the procedures. NOTE: Make sure that you look for organization of ideas and not just a copy of the procedure in boxes. 3. Study Questions: Complete the following questions. (MUST SHOW ALL WORK FOR FULL CREDIT). Note: Kp is equivalent to α (see lecture guide for definition). (a) You wish to extract an organic compound from an aqueous phase into an organic layer (three to six extractions on a macroscale). With regard to minizing the number of transfer steps, would it be better to use an organic solvent that is heavier or lighter than water? Explain. (b) A compound distributes between water (phase 1) and benzene (phase 2) with Kp = 2.7. If 1.0g of the compound were dissolved in 100mL of water, how much compound THREE 10-mL portions of benzene could extract?7(A) - Extraction and Purification of Caffeine from Tea Leaves Pre-lab Report Guideline for Experiment 7(a) Continue Study Questions Continue: (c) If the value of kp is 0.5 for the distribution of a compound between pentane (phase 1) and water (phase 2), and equal volumes of the two solvents were used, how many extractions of the aqueous layer will be required to recover at least 90% of the compound? (d) Calculate the % of a compound that can be removed from the liquid phase 1 by using ONE to Four extractions with a liquid phase 2. Assume that kp = 2 and the volume of phase 2 equals 50% that of phase 1. (e) A slightly polar organic compound distributes between diethyl ether and water with a partition coefficient of 3 (in favor of the ether). What simple method can be used to increase the partition coefficient?
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