Lab Report - Experiement#6

Lab Report - Experiement#6 - Questions 1 We can boil the...

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Questions 1. We can boil the solution to check if there is any boiling point elevation of water, because that occurs when there is any impurity present in the water. Or, in order to check if the sugar molecules are still in the solution is to boil the solution until all the water evaporates, and then see if there is any sugar- like substance left in the container. We may use the melting point measurement to compare the range to that of real sugar. 2. It is not a good idea to use a large excess of activated charcoal to remove colored impurities because of its large surface area. It attracts large or flat molecules with IDID and DID interactions. These attractive forces increase with molecular size so that large molecules are preferentially absorbed. Colored impurities are usually large so that they are more readily absorbed that smaller molecules. So “more is better” does not apply in this case. (source: lab manual pg.108) 3. A depressed and broad melting point can result from wet crystals, impurities, or decomposition during heating. In case of wet crystals, the crystals should be dried, reweighted, and melting point measured again for a correct yield and correct melting point. Also, impurities may exist if the resulting
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This note was uploaded on 11/23/2009 for the course CHEM 3BL taught by Professor Chunmei during the Summer '08 term at Berkeley.

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Lab Report - Experiement#6 - Questions 1 We can boil the...

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