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Duong_Experiment2 - Richard Duong Chem 262L Joseph Sokol 25...

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Richard Duong Chem 262L Joseph Sokol 25 February 2010 Experiment II: Purification of an Unknown by Recrystallization Purpose : To perform a recrystallization of an unknown organic acid in order to obtain its pure form so that the true melting point is able to be determined. Procedure : 10 mL of ethanol was poured into a beaker and heated to boiling on a hot plate. .496 g of unknown number ‘2’ was dissolved in a 10 mL Erlenmeyer flask with the heated ethanol, just the minimum amount. Eventually, 4 mL of heated ethanol was added and the solution contained a yellowish color. A hot filtration system was implemented to remove any insoluble substances. It was done by placing a fluted piece of filter paper into a stemless funnel, which was connected to a different Erlenmeyer flask containing 2 mL of hot ethanol solution and a boiling chip. When the ethanol in flask started boiling and vapors were seen, the unknown solution was poured onto the filter paper to allow the solution to be collected in the second flask, removing any solid impurities. After the solution was filtrated, the solution in the second flask was heated again. Water was added slowly (1 mL portions) until the solution became completely cloudy; 4 mL of water was added until the solution was completely cloudy. The solution was then allowed to cool to room temperature while covered with the watchglass to prevent any impurities from getting in.
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Finally, the solution was put in an ice bath and left to sit for 5 minutes. The color of the crystals was white.
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