C343S2011Quiz2v2KEY

Does this indicate that the unknown is a pure

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Unformatted text preview: y mean one compound. The best way to verify would be to elute in a more polar solvent combination to see if another spot resolved from the spot you had originally. 3. (4 points) Name two major necessities for choosing an appropriate organic solvent for extraction with water. a. The organic solvent must be immiscible with water. b. The solvent must have a different density (this correlates with "a"). c. The solvent must not react with water. C343/F2010 version 2 February 22, 2011 4. a. (3 points) Briefly explain how the rate of crystal growth can affect the purity of your sample? Starting with a saturated solution, if a solution is cooled slowly the impurities will be kept in solution and the crystals will be allowed to form in the purest form. If the temperature is dropped too quickly, the lattice structure will still form, but impurities can be trapped in the lattice leading to an impure substance (as evidenced by lower and broadened mp). b. (3 points) Describe the ideal solvent for recrystallization. The compound to be purified should be very soluble in the hot solvent but have very limited solubility in the cold solvent. c. (2 points) A pu...
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