Aspirin 5

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The crude product (aspirin) was purified in the last lab, using recrystallization, in which we dissolved the crude product with hot ethanol. We then added 25 mL of water until the product reformed (the solution became cloudy white) and redissolved the solid with hot ethanol. The solution was allowed to cool for a week, and crystals of purified solid were formed. In order to analyze this purified product, we determined the melting point by placing a small sample of the aspirin in a capillary tube in the melting point apparatus. A range was found, and compared to the literary range which is between 135 and 135.5 degrees Celcius for a pure substance. We also performed three trials of titrations, in which we titrated the product with NaOH. The NaOH only reacts with the acid proton on the aspirin and allows us to determine the moles of acid in the sample, provided that the aspirin is not contaminated. The amount of purified aspirin that was formed after recrystallization was 2. 1635 g and the melting range for my sample of aspirin was 125.1 to 131.3 degrees Celcius (melting point).


After the product recrystallized and was drained of solution and impurities, there was 2.2635 g of aspirin. The percent recrystallized yield was 55 percent. Three titrations were performed in which .1021g, .1102 g, and .1091 g of aspirin were used and the end point volumes were 2.80 mL, 3.00 mL, and 2.90 mL, respectively. The melting point range of my sample of aspirin was 125.1 degrees Celcius to 131.3 degrees Celcius (melting point). The literature value of the melting point is 135 to 135.5 degrees Celcius. My melting point is lower than the literature value which is caused by the presence of a small amount of impurities; also my melting point range is larger than the literature range, which is due to impurities remaining in my product. This difference in melting points and ranges shows that my aspirin is not a completely pure substance, even after...
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