Echem Lab One - Alyson Waring 03/09/08 Synthesis of Aspirin...

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Alyson Waring 03/09/08 Synthesis of Aspirin and Determination of Purity by Colorimetric Analyses Introduction In this experiment, combining an acid and an alcohol and then heating the mixture synthesized aspirin. The resulting product was tested for its purity by determining its melting point and through colorimetric analyses. Colormetirc analyses works by measuring how much light a solution absorbs. Knowing the absorption values, one may calculate the concentration of solute within the solution. Comparing the absorption value of an experimentally produced product against a standard curve of a pure product allows the determination of the concentration of the experimental. This curve can be used to determine the concentration of the experimental. The melting point analyses aids in determining purity because the recorded experimental value can be compared to the known melting point of the 100% pure product. If a lower melting point is observed, it may indicate impunities within the substance. Experimental Part One: Aspirin Synthesis Aspirin was synthesized by the combination of salicylic acid and acetic anhydride. salicylic acid + acetic anhydride aspirin + acetic acid C 7 H 6 O 3 + C 4 H 6 O 3 C 9 H 3 O 4 + C 2 H 4 O 2 2.99 grams of salicylic acid was weighed and placed into a 125mL Erlenmeyer flask. 6mL of acetic acid and five drops of sulfuric acid (H 2 SO 4 ) were added and mixed by swirling of the flask. A hot water bath (80-90 ° C) was prepared and the flask was heated
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for 20 minutes. After being allowed to cool to room temperature, 40mL of distilled H 2 O was added and the flask was placed in an ice bath to promote crystallization. To aid crystal formation, a glass rod was used to scrape the sides and bottom of the flask. Once completely crystallized, the solids were isolated through vacuum filtration. When all crystals were separated from the mixture, the newly synthesized aspirin was rinsed with ice cold distilled H 2 O and patted dry with filter paper. Table 1 Reagent Amount Used Molecular Weight Moles Used Salicylic Acid 2.99g 138.12 g/mol .0216 mol Acetic Anhydride 6mL 108.09 g/mol .635 mol Part Two: Aspirin Purification To purify the aspirin, the crystals were dissolved in 9mL warm (70 ° C) ethanol. The mixture was warmed in a hot water bath (70
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This note was uploaded on 04/09/2008 for the course BIOL 122 taught by Professor Kanda during the Spring '08 term at Ithaca College.

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Echem Lab One - Alyson Waring 03/09/08 Synthesis of Aspirin...

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