Crystalization and Melting Points

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Crystallization and Melting Points
Organic Chemistry 221
9/19/2012
Intro/Purpose:
The purpose of this lab was to use crystallization to separate a compound from a solvent and be able to choose the best solvent to do so. Then identify an unknown and verify purity using melting points. Solubility contributes to crystallization; because a solute has lower solubility at lower temperatures, which makes the solvent separate from the solution as a solid. This process is important to understand because it is very effective in separating compounds so we can get a closer look at the components of the solutions. Procedure:

We were required to complete parts B, C, D and E. The procedure for parts B, C and D were followed by the book. (CHMY 221/223 “A Microscale Approach to Organic Laboratory Techniques,” 5th Edition, Donald L Pavia, George S. Kriz, Gary M. Lampman, Randall G. Engel, 2013, Cegage Learning pages 26-30 and 687-693). Part D involved identifying an unknown. Part E involved using polarity and solubility theories to determine the best solvent for crystallization, which compound was too soluble and which compound was not soluble enough. The Merck Index was used to get exact solubility’s and polarities to determine which solvent would be best to crystallize the given solute. Data/Observations:

In part B the book stated that dissolving the sulfanilamide would take no longer than 15 minutes. It took us almost two hours. This could be due to the fact that we did not have the hot plate at the proper temperature to begin with, in order to dissolve the sulfanilamide. The amount of time it took to dissolve the sulfanilamide made me think that we did something wrong and our results would not be accurate. Crystallization:

Part B:StartFinish% RecoveryExpected Remaining
Sulfanilamide0.093g0.059g68.6%0.034g

Part C:StartFinish% RecoveryExpected Remaining
Fluorene0.044g0.018g48.6%0.026g

Melting Points:
CompoundLiterature Melting...
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