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Properties of Aspirin Lab 38 Purpose- The objective of the lab was to determine experimentally the physical properties of aspirin and its chemical properties. Procedure- We followed the procedure in the lab book. Results Solubility Tests: Solvent Salicylic Acid Aspirin Methanol soluble slightly soluble Toluene slightly soluble insoluble Cold water insoluble slightly soluble Hot water insoluble slightly soluble Functional Groups: Test Reagent FeCl3 turned purple aspirin dissolved NaHCO3 became soluable bubbles formed Trial 1 Trial 2 Discussion In this lab we examined the properties of normal household aspirin tablets (acetylsalicylic acid) through the titration and calculation of pH levels using a pH meter. By determining the pH with the pH meter, the pKa and Ka can be calculated. After such calculations, the molecular mass of aspirin can be obtained by dividing the moles of aspirin used into the grams of aspirin used. This lab is an example of how pH and the acidity constant (Ka) can be used to not only determine molecular mass of a substance, but also the chemical structural formula of a substance (acetylsalicylic acid C9H8O4). We also performed solubility tests in order to determine the solubility of salicylic acid and aspirin methanol, toluene, cold water, and warm water. Finally we added test reagents to these solutions and recorded the effect that each had on the aspirin and salicylic acid solutions. Questions 1. The evidence that the aspirin tablets are not pure acetylsalicylic acid lies in the fact that the aspirin tablets were not soluble in water when we performed the solubility tests. 2. The affect that an 85% pure tablet would have on the molecular mass would be that the derived molecular mass from experimentation would be higher because other substances in the tablet might account for some changes in the pH in the titration. 3. Because there may be other substances in the tablet that would effect the pH of the solution being titrated, there may be an increase in the Ka value for the aspirin.
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