The melting point of the purified product was lower than the expected 135 degree Celsius melting point of aspirin, which revealed to us that the purified aspirin product still contained some impurities. You now have air-stable crystals of pure salicylic acid! Acetic anhydride solves this problem for the reason Matt Harbowy explains. Compare the literature melting point and infrared spectrum to the experimental and comment on the purity of your aspirin. Allow the sample to vacuum dry for 5 minutes. The phenol test was to test the purity of the aspirin product that was created during the experiment.
The mass of pure acetylsalicylic acid was determined and recorded and the percent yield of the reaction was calculated Table 2. Scratch the bottom of the Erlenmeyer flask with a glass stirring rod with strong force. Ibele April 17, 2015 Introduction: The first law of thermodynamics states that energy cannot be created nor destroyed. These plants contain a compound called salicylate, which creates these curative attributes. The purified product started to melt at 86 degrees Celsius and finished completely melting at 102 degrees Celsius.
However, I'd just like to add a little bit more to his answer. From that structure we can begin to understand why and how chemical reactions occur. Can you identify the limiting reactant in the synthesis? The contents of each tube and 50 mL distilled water were then added to a 125 mL Erlenmeyer flask. Cool the mixture slightly in an ice bath until crystallization is completed. Salicylic acid is irritating to the skin and sulphuric acid causes severe burns.
It was not digital and did had a disk shaped scale. This method of forming acetylsalicylic acid is an esterification reaction. Do not add the water until crystal formation is complete. At higher temperatures warm water , molecules have more kinetic energy and collide with each other more often to interact with water molecules, increasing the solubility of the aspirin. Finally, filter out your salicylic acid crystals, wash the crystals in the filter once more with a small amount of ice-cold water, and dry the crystals. The general mechanism for catalysation by a base, like the acetate ion or pyridine, is shown in Figure 2.
Purification is needed to eliminate any salicylic acid and acetic anhydride that did not react, as well as the acetic acid product and phosphoric acid. To purify the crude product, water was added to solution to further lower the solubility of acetylsalicylic acid and to dissolve some of the impurities from the crystal. There were many reasons to this. Transferred crystals to Buchner funnel and did vacuum filtration. Determination of purity - a melting range greater than 2 degrees C indicates an impure compound 2.
After cooling in an ice bath which further facilitates recrystallization and purification , the mixture was then suction filtered. Monitoring the rate of a reaction via temperature change is not the most accurate method of measuring reaction rate because it is so indirect. Although there were many errors it was a surprising to get a yield of around 80%. This is a substitution reaction where the alcohol group from salicylic acid reacts with ascetic anhydride to form an ester, acetylsalicylic acid which is commonly known as Aspirin. This is for the reaction to occur while preventing the aspirin from re-crystallizing prematurely? Dissolve the compound in the smallest amount of hot ethanol 2. Leave the 125 mL Erlenmeyer flask that contains the mixture in its ice bath and allow it to cool for an extra 5 minutes. The weight of the recovered sample was 2.
In the fume hood, add approximately 3. In this experiment aspirin, also known as acetylsalicylic acid, was synthesized from salicylic acid and acetic anhydride. The melting point of the Acetylsalicylic acid Aspirin was found to be 121°C according to the experiment carried out. While their extract was somewhat effective, it also caused digestive problems such as , , and even death when consumed in high doses. How did this affect the end product? As you see it starting to melt makes a note of the temperature.
Transfer 90% of salicylic acid into a 50 mL Erlenmeyer flask 3. Remove a pea-size amount of the crystals from the Büchner funnel and set aside to determine the melting point and infrared spectrum of this crude sample. Determine the melting point of your aspirin sample Your instructor will demonstrate how to use the melt-temp apparatus. Heat it for fifteen minutes with occasional stirring. The safety goggles were used to ensure, chemicals did not come in contact with the eyes or areas near to the eyes. The experiment starts by combining such chemicals such as salicylic acid and acetic anhydride.
Transfer the crystals to a beaker. Perhaps, the sample was not weighed properly or it was weighed when still wet. Hypothesis: The following hypothesis will be tested:? Generally take more care with the experiment. At high temperatures, it behaves like alcohol! In this lab, for recrystallization, the solution was allowed to cool to room temperature very slowly, but was then plunged rapidly into ice water. Due to apparent wetness of the product it is estimated that half of the mass is due to moisture. Taking this into account, the actual mass of the purified aspirin product is reduced to 0.