118K Extraction Recrystalization

118K Extraction Recrystalization - solution must not vary...

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Michael Tam(mht347) 2/27/2011 Extraction/Recrystalization Conclusion Utilizing Extraction, we separated a mixture of two chemicals by capitalizing on the solubility of the solvent relative to the solute. We then purified the remaining solid using Recrystalization. Extraction exploits the difference in solubility between solvents. NaOH was used to extract the acidic component in the unknown, HCl was used to extract the basic component in the unknown, and Sodium sulfate was added to the unknown component of the unknown, acting as a drying agent. After adding each extracting solvent to the separatory funnel, the funnel is thoroughly shaken to maximize the surface area between the two phases. Once the mixture is separated, we purified the solid part using Recrystalization. Recrystalization depends on a few main things. The compound of interest must be insoluble in cold, soluble in hot, easily separated from the solution, and the impurities also dissolved in the
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Unformatted text preview: solution must not vary in solubility depending on the temperature. The data we obtained seemed somewhat congruent with the theory. Our % yield seemed a little higher than normal after extraction, perhaps due to moisture. This was supported by letting the samples dry for a week and reweighing them. Moisture could have potentially add a lot of weight, especially when dealing with such tiny samples (less than a third of a gram). Both after extraction and Recrystalization the melting points were almost identical, pointing to the fact that very little impurities were in the glassware during the experiment. Potential sources of error include: weighing moisture, spillage, not being able to weigh all of the solid when it sticks to the glass, and cooling after Recrystalization too quickly. All in all, the data was consistent and pointed to the fact that the acid/base/neutral unknown was indeed 1:1:1 ratio, and was separated properly....
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This note was uploaded on 09/25/2011 for the course CH 118K taught by Professor Fjetland during the Spring '08 term at University of Texas at Austin.

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