March 19, 2012
•Introduction/Objective: Prepare and analyze aspirin from salicylic acid and acetic anhydride, and calculate the percent yield of the synthesized aspirin. •Materials and Methods: This experiment called for the synthesis of acetylsalicylic acid, or aspirin, by using salicylic acid, acetic anhydride, sulfuric acid, and vacuum filtration. The salicylic acid and the acetic anhydride were mixed in a flask. Sulfuric acid was used as a catalyst to speed up the decomposition rate of salicylic acid. Vacuum filtration as then used to remove all water from the aspirin sample. Afterward, the aspirin was analyzed by using chromatography which confirmed the purity of the aspirin. •Results: The results of this experiment showed that the aspirin synthesized was not completely pure since there were miniscule traces of salicylic acid present in the aspirin sample. This was evident after analyzing the chromatographic paper under UV light. The calculated yield of the dried aspirin sample was 74.09 percent totaling a mass of 2.03 grams of aspirin with a theoretical yield of 2.74 grams. •Discussion: There may have been some room for error in this experiment. After adding the acetic acid anhydride and the sulfuric acid into the flask, the flask could have been swirled for a longer period of time to increase the chance of all the salicylic acid being dissolved. Also, the sample could have been kept on the aspirator for a longer period of time to ensure that all water was removed from the aspirin sample before weighing it. Introduction:
•Purpose/Objective: Experiments like these are important since the right amount of salicylic acid and acetic anhydride must be mixed in order to synthesize pure aspirin. Aspirin is an important supplement to take to relieve pain, fevers, and reduce the risk of possible heart attacks. •Theory: In order to make the results of this experiment meaningful, there is some background knowledge that needs to be known such as using laboratory equipment properly. Also, it must be known that sulfuric acid acts as a catalyst in the experiment. There needs to be very precise measurements of salicylic acid, acetic anhydride, and sulfuric acid in order to create the purest aspirin sample possible. And lastly, there needs to be careful calculations of mass and moles in order to obtain accurate yields. •Equations: There are several equations used in this lab. Equation 1 was used to calculate the number of moles of salicylic acid: (mass of salicylic acid, g)(1mol salicylic acid/138.12 g salicylic acid). Equation 2 was used to calculate the mass of acetic anhydride: (Volume of acetic anhydride, m)(Density of acetic anhydride, g/mL). Equation 1 was also used to calculate the number of moles of acetic anhydride: (grams of acetic anhydride)(1mol acetic anhydride/102.09 g acetic anhydride). Equation 3 was used to calculate the theoretical yield: (Number of moles of limiting reactant)(1mol aspirin/1mol limiting reactant)(180.15 g aspirin/1 mol aspirin). Equation 4 was used to calculate the percent yield: (actual yield, g)/(Theoretical yield, g)(100%). Notice that equation 1 was used to calculate the number of moles of both salicylic acid and acetic anhydride. •Method: The key components in the experiment are salicylic acid, acetic anhydride, sulfuric acid, and chilled distilled water. The Büchner funnel was used to vacuum filtrate the water from the synthesized aspirin through a filter paper. In analyzing the sample, the technique used was chromatography. This process was used to determine the purity of the aspirin sample that was synthesized. Materials and Methods:
•Ice and Water
•50-mL Erlenmeyer Flask
•10-mL Graduated Cylinder
•100-mL Graduated Cylinder
•Weighing Paper and Watch Glass...