Aspirin Lab Report
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Ximena Delgado Ms. Petty Chemistry HL-Pd. 5 18/04/11 Aspirin Lab Report Introduction Aspirin is an acid. In order to make an aspirin there is a mix of salicylic acid and acetic anhydride with H2SO4.The synthesis of aspirin is an esterification, in other words it's when an acid and an alcohol mix together in order to form a product which in this case it's an aspirin. However esterification is a reversible reaction. Different strengths of aspirin are based on the amount of active ingredients that they contain. Titration is a way to determine how much acid is in a solution by adding just enough base of a known concentration to neutralize the acid. In neutralization, the number of moles of acid, H+, are combined with an equal number of moles of base, OH-. The aspirin will be titrated against a standard solution of base, 0.100 M NaOH. Base will be dispensed from a biuret into a beaker containing the dissolved (in ethanol) acid and phenolphthalein indicator, which will show a faint pink color in basic solutions. This range of colors determines the color change interval and it expresses the pH range.
Uncertainty of initial volume of NaOH: Uncertainty of final volume of NaOH: Uncertainty of ethanol: Overall uncertainty= 0.1152% + 0.1817% + 0.1118% + 0.5% =0.9087% Data presentation Conclusion Evaluation The mass of 3 tablets of aspirin was . Find the mass of a children's aspirin, regular aspirin and extra-strength aspirin tablet. Grind each tablet into a fine powder by using a mortar and pestle. 2. Tare a piece of weighing paper on the balance. Carefully transfer as much powdered sample to a piece of paper and then determine the mass. 3. Place the powdered sample in a 150mL beaker. 4. Add a 10.0 mL portion of ethyl alcohol to the beaker and stir. 5. Add 25.0mL of water to the beaker. 6. Put 3 drops of the phenolphthalein indicator in your flask. Put a magnetic stir bar in your flask and place the flask on the center of the stir plate. 7. The buret is filled with 0.100M NaOH. Make sure there are no bubbles apparent in the buret. Record the initial volume on the buret. 8. Begin titrating, Add the NaOH in 1.0mL increments, making note of when the color change occurs.
Amount of Active Ingredient in Product Tested 1. Calculate the moles of base used to neutralize the acid for each type of aspirin. 2. Acetyl salicylic acid (C9H8O4) is not a strong acid, which means that for every mole that dissolves, not an entire mole of H+ dissociates from the acid. Nevertheless, what hydrogen ions that did dissociate were completely neutralized by the hydroxide added from the base. How many moles of H+ were neutralized? 3. For simplicity's sake, we are going to assume that acetyl salicylic acid is a strong acid, and, therefore, the initial moles of H+ equals the initial moles of acid. Since we are comparing aspirin to aspirin, we will be able to obtain a relative comparison of the amount of acid in each aspirin. Calculate the mass of the acid for each aspirin based on the number of moles that reacted with base. 4. Check the label on the bottles and determine if your calculation in #3 is valid. Account for any discrepancies in your calculation. Conclusion: 1. Analyze the cost differences between Bayer, generic, and baby aspirin. 2. Which type of aspirin would you buy? explain your answer 3. Explain some sources of experimental error in our experiment. (Be specific) 4. Why are aspirin substitutes used by many people? Research needed here!
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