EXP5 - Fijany 47 Layla Fijany Chem 12A T/TH 5-10pm...

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Fijany Layla Fijany Chem 12A T/TH 5-10pm 10/25/2011 Experiment 5: Chromatography Purpose : To give practice in separating components of a mixture using chromatography. To determine which solvent would be best for separating a pair of related compounds that differ slightly in polarity. Introduction: Chromatography works on much the same principle as solvent extraction. In extraction, the components of a mixture are distributed between two solvents according to their relative solubilities in the two solvents. The separation process in chromatography depends on differences in how strongly the components of the mixture are absorbed to the stationary phase and how soluble they are in the moving phase. This technique uses the distribution of the different compounds or ions in the mixture between two phases, one of which is stationary and the other moving. These differences depend primarily on the relative polarities of the components in the mixture Hypothesis: The stronger one component is absorbed to the stationary and the greater the solubility of the second component in the moving phase, the greater the distance on the chromatography paper. Set Up: 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, 47
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Fijany 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 Methyl Alcohol (CH 4 O) : 32.05 64.7 -98 0.7918 - reacts violently with acids, reducing agents, highly flammable; colorless, volatile, poisonous Fluorenone (C 13 H 8 O): 180.2 342 83.5 1.13 - used to make antimalaria drugs; yellow flakes, chips or crystalline powder Fluorenol (C 13 H 10 O): 182.22 -- 152 - off-white crystalline powder, practically insoluble, alcohol derivative of fluorene Sodium Borohydride (NaBH 4 ) 37.83 500 400 1.07 - white crystals, soluble in water used as bleaching agent for wood pulp used in oxymercuration reactions; basic borate salts that can be corrosive, may be flammable. Pre-Lab Questions Pg 800: 1-5 1. The components are most likely not soluble in dichloromethane and hence never entered the mobile phase, i.e., the solvent. The polarity of the solvent system should be changed by trying various combinations of polar:nonpolar solvents and to determine which one gives the best separation. 2. Naphthalene is very nonpolar so a very nonpolar solvent like hexane should be used. 3. Biphenyl is an unsaturated hydrocarbon, and therefore is the least polar and will have the largest R
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This note was uploaded on 02/26/2012 for the course OCHEM 12A taught by Professor Alston during the Fall '11 term at Saddleback.

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EXP5 - Fijany 47 Layla Fijany Chem 12A T/TH 5-10pm...

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