EXP11 - 1 Fijany Layla Fijany Chem 12A T/TH 5-10pm...

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1 Fijany Layla Fijany Chem 12A T/TH 5-10pm 10/25/2011 Experiment 11: Isolation of Caffeine Purpose : To isolate caffeine from tea using several techniques, such as: extraction, distillation, crystallization and sublimation. Introduction: The isolation of caffeine from tea leaves presents the chemist with a major problem: caffeine does not occur alone in tea leaves, but is accompanied by other natural substances from which it must be separated. Caffeine is a common substance found in coffee, tea, soft drinks, chocolate, and energizing pills or drinks. Caffeine is an alkaloid, a class of naturally occurring compounds containing nitrogen and having the properties of an organic amine base. This experiment illustrates the isolation of a naturally occurring product from plant material -caffeine from tea leaves. Hypothesis: The closer the experimental melting point of the caffeine isolated to that of the literature melting point, the purer the caffeine. If the melting point is lower, then it can be assumed that there are impurities in the substance. Set Up:
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2 List of Reagents FW (g/mol) BP (˚C) MP (˚C) Density (g/cm 3 ) Other (hazards, uses, etc) 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 Acetone (C 3 H 6 O): 58.09 56 95 0.7925 - clrless, mobile, extremely flammable lqd, may depress CNS; miscible in water; used as cleaning, nail polish remover; good solvent Caffeine (C 8 H 10 N 4 O 2 ): 194.19 178 227-228 1.23 -bitter, white crystalline, xanthine alkaloid used as a psychoactive stimulant, has been shown to increase a person’s capability for mental or physical labor Anhydrous sodium sulfate (Na 2 SO 4 ): 142 1429 884 2.66 - white crystalline solid, stable and unreacting to reducing agents at room temperature; dust can cause temporary asthma or eye irritation
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EXP11 - 1 Fijany Layla Fijany Chem 12A T/TH 5-10pm...

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