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Unformatted text preview: Lab 7 Discussion The solvents of choice were 100% ethyl acetate and 92:8 ethyl acetate: acetic acid. These solvents were chosen among 4 solvents, the other two being 10:10:1 toluene: ethyl acetate: acetic acid and 60:40 hexane: ethyl acetate. The two solvents were chosen based upon the extent of separation. The hexane and ethyl acetate solvent did not have enough separation, as was indicated by the relatively low R f values. This meant the solvent was not acceptable because the compounds were too polar as a mobile phase. The relative differences in polarity of the compounds were too close to distinguish. The other mixture of toluene, ethyl acetate, and acetic acid did not separate the compounds as well. The caffeine exhibited very little movement. Also, the acetaminophen was split into two, which means it was perhaps reacting with the substance in a way that would make it difficult to identify. The ethyl acetate and ethyl acetate: acetic acid mixture both provided good R f values because they are the least polar of all the solvents. Since the solvent is the mobile phase, it is ideal to have a nonpolar solvent. The relative polarity of the compounds is therefore able to be determined because the order determined by molecular polarity will be constant. Aspirin was identified through chromatography in ethyl acetate and the ethyl...
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This note was uploaded on 02/21/2011 for the course CHEM 3A taught by Professor Fretchet during the Spring '08 term at University of California, Berkeley.
- Spring '08