This lab has the following two concepts: synthesis of acetylsalicylic acid and analysis of acetylsalicylic acid. Synthesis is a purposeful execution of chemical reactions to obtain a product. This concept is used in the first part of the lab; when we have to produce crystals of aspirin. Analysis is the separation, identification, and quantification of the chemical components of natural and artificial materials. This concept is used throughout the lab when we are analyzing different reactions that are happing during the duration of the lab. The goal of this lab is to synthesize a sample of acetylsalicylic acid, otherwise known as aspirin. This is the most important goal of the lab. This, however, has side goals that go along with the main one. One is finding the percent yield of the synthesis. Another is measuring the melting point of the aspirin sample, which will in turn indicate the purity of the sample. The last is conducting a colorimetric analysis on the aspirin sample. The educational goals of this lab are to find the structural formulas for salicylic acid, acetic anhydride, and aspirin and to use these structural formulas to construct a reaction equation by describing the synthesis of aspirin. In addition, you have to be able to use your percent purity calculations to determine the percent yield of your synthesis of aspirin. Methods and Materials
Part I: Synthesis Aspirin
Goggles were obtained and put on before entering the lab area. 2.0 grams of salicylic acid should be measured and placed into a 125 mL Erlenmeyer flask. 5.0 mL of acetic anhydride and 5 drops of 85% phosphoric acid was added to the Erlenmeyer flask. Drops of distilled water were added to rinse down bits of solids that were on inner wall of the flask. Mixture was heated on the hot plate for fifth-teen minutes, at 75 degrees Celsius. Two mL of distilled water was added 10 minutes into heating. Buchner funnel and filter were set up for the filtration process. Reaction was completed and 20 mL of distilled water was added to the flask. Flask was cooled for 5 minutes in an ice bath. Aspirin crystals were formed after cooling of the flask. Contents were transferred into Buchner funnel assembly. The mixture was filtered with the assistance of the vacuum. When all liquid had drained out, suction was stopped. Then 5 mL of cold distilled water was added and after 15 seconds the vacuum was turned back on. This procedure was repeated two more times in the same manner. Aspirin crystals were stored in a safe place for purity test. Part II: Test the Melting Temperature of an Aspirin Sample
Temperature Probe was connected to the Lab Quest deceive and new file was opened. About 0.2 grams of aspirin was placed into the mortar. The pestle was used to pulverize the aspirin inside the mortar. A capillary tube was obtained. Aspirin was packed to the 1 cm marked inside the capillary tube. Capillary tube was fastened to the temperature probe by a rubber band. A mineral bath was heated up on the hot plate. Capillary tube-Temperature Probe was immersed inside mineral oil bath. The melting point was recorded as precise as possible. A second test was conducted with a new sample of aspirin in a new capillary tube.
Part III: Test the Colorimetric Absorbance of an Aspirin Sample Next, about 0.20 g of salicylic acid was recorded. It was then transferred to a 250mL beaker and 10mL of 95% ethanol was added and swirled until it was all dissolved. 150mL of distilled water was then added and mixed with the solution in the beaker. The contents were then placed into a 250mL volumetric flask. Distilled water was added until it hit the 250mL mark on the flask. The molar concentration was calculated and recorded. Next, four standard solutions of varying concentrations were created. 100mL of the standard solution was prepared with 10mL of the previously made solution into a volumetric flask. 0.025 M Fe(NO3)3 solution was added to make precisely...
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