EXP3 - 1 Layla Fijany Chem 12A T/TH 5-10pm 9/15/2011...

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1 Layla Fijany Chem 12A T/TH 5-10pm 9/15/2011 Experiment 3: Extraction Purpose: The purpose of this lab is to become familiar with the technique of extracting caffeine, determining the amount of solute in an aqueous and organic layer to calculate the distribution coefficient, learning how to determine the organic layer and lean how to use extraction to remove an acid or base to isolate a neutral compound. Introduction: Extraction is a technique used to isolate and purify organic substances. This technique is used to extract a solute from one solvent to another because the solute will be more miscible in the second solvent that the first. It is critical that the two solvents must not be miscible and must form two separate layers because the whole point is to separate the layers (with a separatory funnel, conical vial or centrifuge tube). Extraction is not only used in organic chemistry labs, but it is also a commercial method of making decaffeinated coffee. Because caffeine stimulates the central nervous system and skeletal muscles, many people prefer decaffeinated coffee. There are several different methods to remove the caffeine from coffee beans: direct contact (uses organic solvents), water process (no use of organic solvent), or carbon dioxide decaffeination process (raw beans moistened and treated with CO 2 in a supercritical state). Also, many natural products have high water content and extraction is used with a water-immiscible solvent to isolate these products. Background knowledge of solubility of various solids, solutes, and solvents is necessary to be successful in predicting whether a solute will be in the organic or aqueous layer. Hypothesis: The best extraction that will yield the most substance is that which is repeated several times with smaller amount of solvent than one extraction with a large volume of solvent. The organic layer can be determined by looking comparing densities (from literature source) or by adding a small amount of the organic solution to the test tube and observing which layer increases in volume. Set Up: List of Reagents: FW (g/mol) BP (˚C) MP (˚C) Density (g/cm 3 ) Other (hazards, uses, etc) Diethyl Ether (C 4 H 10 O): 74.14 34.6 -116.3 0.7134 - colorless, volatile, extremely flammable lqd, odor; RI( n D Methylene chloride (CH 2 Cl 2 ): 84.93 39.6 -96.7 1.33 - clrless lqd, high volatility, inhalation hazard, metabolized by body to CO (poisoning), carcinogenic; used as paint stripper, degreaser, aerosol spray propellant and to decaffeinate coffee/tea Benzoic acid (C 7 H 6 O 2 ): 122.13 250 122.38 1.27 - clrless crystal solid; used as Sodium Hydroxide
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EXP3 - 1 Layla Fijany Chem 12A T/TH 5-10pm 9/15/2011...

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