Krieger.Jackson.AspirinSynthesisCrystallizationandCharacterizationDLR.docx

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CHEM113 Sturtz Aspirin Synthesis, Recrystallization and Characterization D IGITAL L ABORATORY R EPORT PREPARED BY : J ACKSON K RIEGER D ATE : F EBRUARY 27 TH , 2024 L AB R OOM : M ILLIS 210 S ECTION : T UES /4:15 PM TA: M D S IRAJUL I SLAM Procedure - Must be in third person, past tense, passive voice, and paragraph format. A 150mL beaker (reaction beaker) was taken to the balance room and after 2.8936g of salicylic was measured on a piece of weighing paper, the salicylic acid was transferred into the reaction beaker. This mass was recorded. A 10mL graduated cylinder was used to obtain 9.55mL of acetic anhydride and a watch glass was used to cover the graduated cylinder to prevent the spread of acetic anhydride fumes. This volume was recorded. Inside the hood, the acetic acid was added to the reaction beaker along with 15 drops of 85% phosphoric acid. The magnetic stir bar was put in the reaction beaker and the reaction beaker was placed on the hot/stir plate. While the stir setting was set to around 100, the temperature displayed on the hot plate was slowly increased from 60-250 ℃ and turned off immediately when the solution started to bubble. After taking the reaction beaker off the hot plate and letting it cool for approximately 3 minutes, 45 drops of DI water were slowly added to the reaction beaker. Once the drops were added, an additional 30mL of DI water was poured into the reaction beaker. The solution was then swirled. Since the solution stayed clear it didn’t need to be reheated. While the solution was cooling, crystallization was induced by using a glass stir rod to scratch the bottom and walls inside of the reaction beaker. A 400mL beaker filled about a third of the way with ice and enough DI water to cover the ice was used as an ice bath. The reaction beaker was placed in this ice bath for a total of 15 minutes. However, every 5 minutes the reaction beaker was removed, and the glass stir rod was used to gently scratch the inside of the reaction beaker. During the waiting period, the vacuum filtration apparatus was prepared. A second ice bath identical to the first one was prepared. Then a 150mL beaker was filled with approximately 100mL of DI water and placed inside the new ice bath. With the clamp in the hood, a filtration flask was secured before being connected from its side arm to the water aspirator with a rubber tube. A Büchner funnel was then placed on the top of the flask, with a seal being created by a vacuum adapter. After, the contraption was set up, a piece of filter paper was placed in the funnel and then wet with DI water. The water aspirator was turned to full, and the suction through the funnel was tested. Once the reaction beaker had been in the ice bath for 15 minutes, the reaction mixture was slowly poured into the funnel. This caused the liquid to pass through and the solid to stay up top. The solid that was stuck in the reaction beaker was scrapped out using a spatula. When all of the reaction mixture was transferred, the aspirin crystals were washed with approximately 10mL of the chilled DI water from the second ice bath. After 5 minutes this was repeated. During this time, the crystals were periodically moved around using the spatula to ensure the liquid was removed. The crystals were then left to dry by leaving the water aspirator on for 10 minutes. When the 10 minutes were up, the water aspirator was turned off. The dried aspirin crystals were transferred to a watch glass and spread evenly. Then the watch glass was placed in the oven for 20 minutes. During this time, a six-dram vial (without the lid on) was weighed at 18.1846g and this mass was recorded. Once the aspirin was out of the oven, a piece of weigh paper was used to transfer the crystals into the vial. The weight of the vial with the aspirin was 21.9260g meaning the aspirin weighed 3.7414g. Both of these values were recorded. The theoretical yield, limiting reagent, and percent yield were calculated using the provided equations. A melting point tube was stuck in the crude aspirin to obtain about 1-2mm of the crude aspirin. After ensuring that the sample was at the bottom of the tube, it was placed in the Mel-Temp apparatus. The temperature when the first crystals just started to melt was recorded at 136 ℃ and the temperature when the last crystal disappeared was recorded at 140 ℃ . These temperatures produced the melting range of the crude aspirin produced.

CHEM113 Sturtz Data Table(s) - Must be in table form to receive full credit. Mass of salicylic acid (g) 2.8936 Volume of acetic anhydride (mL) 9.55 Mass of empty vial (g) 18.1846 Mass of vial with aspirin (g) 21.9260 Mass of dry aspirin (g) 3.7414 Sample Calculations - General equations are shown. Beneath the generic equation, you must show a sample calculation with your numbers plugged in, then write the calculated value. Theoretical Yield: ?ℎ?????𝑖??? 𝑦𝑖??? = ???? ???????? ? ( ) × 1 ??? ???????? ????? ???? ???????? (?) × ? ??? ??????? ? ??? ???????? × ????? ???? ??????? (?) 1 ??? ??????? ?ℎ?????𝑖??? 𝑦𝑖??? = 2. 8936? ???𝑖?𝑦?𝑖? ??𝑖? × 1 ??? ???𝑖?𝑦?𝑖? ??𝑖? 138.121? ???𝑖?𝑦?𝑖? ??𝑖? × 1 ??? ???𝑖?𝑖? 1 ??? ???𝑖?𝑦?𝑖? ??𝑖? × 180.158? ???𝑖?𝑖? 1 ??? ???𝑖?𝑖? = 3.7743g aspirin Percent Yield: ??????? 𝑦𝑖??? = ???? ?? ??????? ????𝑖??? (?) ???? ?? ?ℎ?????𝑖??? 𝑦𝑖??? (?) × 100 = 99.12% ??????? 𝑦𝑖??? = 3.7414? 3.7743? × 100 Results - Must be in table form to receive full credit. Theoretical yield based on salicylic acid (g) 3.7743 Theoretical yield based on acetic anhydride (g) 18.2 Limiting reagent salicylic acid Percent yield (%) 99.12% Melting Range ( ℃ ) 136-140

CHEM113 Sturtz Conclusion Questions - Must be answered in complete sentences for full credit. Using ChemDraw draw the full balanced chemical reaction for this experiment. Be sure to include all sideproducts. What was your theoretical yield and what was your percent yield? My theoretical yield using salicylic acid was 3.7743g of aspirin and my theoretical yield using acetic anhydride was 18.2g of aspirin. Therefore salicylic acid was the limiting reagent and the theoretical yield of 3.7743g was used in my percent yield calculations. The percent yield was calculated to be 99.12%. An accurate percent yield must be below 100% Why? A percent yield that is over 100% means that more product was produced than the reactants should theoretically be able to produce. This likely, means that the product contains some impurities that it shouldn’t. This could happen if the product is not pure and there were substances left in the aspirin that weren’t meant to be left. What error(s) may have caused a percent yield higher than 100%? Cooling the reaction beaker too quickly and causing crystallization to occur too quickly could result in a percent yield higher than 100%. This is because if crystallization happens too quickly, the crystal could form around substances that aren’t meant to be in the crystal causing impurities. If extra substances were trapped in the crystallization, the weight of the aspirin could be higher than what it was theoretically calculated to be. These extra impurities could also have been left in the aspirin if the sample wasn’t washed enough. Then there could have been extra weight if the aspirin wasn’t completely dry and still had water in it, increasing its mass. What did you do in the procedure to try to prevent the error(s) named above? To prevent these errors, I first let my sample cool down by itself before slowly adding drops of water. Then once the sample had been cooled down a little already, and water had been added, I placed the reaction beaker in the ice bath. Immediately placing the sample in the ice bath would’ve cooled down the sample too quickly. Then when rinsing, I used around 20mL of DI water in total to make sure no impurities were left over. Finally, the aspirin was placed in the oven for 20 minutes to make sure it was thoroughly dried. Explain how differences in solubility are used to purify aspirin in the recrystallization step ( Part II ). Aspirin is soluble at high temperatures so it is dissolved in the solute. The impurities are also dissolved at this time. However, at lower temperatures aspirin is not soluble so as the sample was cooled down during crystallization, the aspirin began to crystalize out of the solution. The soluble impurities still remain dissolved in the solute. Filtration was then used to separate aspirin from the impurities. Therefore, the differences in solubility between aspirin and the impurities allowed aspirin to fall out of the solution when cooled.

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CHEM113 Sturtz Does your melting point data support your successful synthesis of aspirin? Explain how the data you collected supports your conclusion. After looking at an SDS page, I found that the melting point/range of aspirin is 134-136 ℃ . My aspirin had a melting point range of 136-140 ℃ . This means that my aspirin is very close to pure aspirin, it just has a slightly higher melting point with a slightly higher range. This means that my aspirin is pretty close, but it is not 100% pure and does have some impurities.