Lab 8 Aspirin Synthesis Sample Report PDF

Preview

Summary

Need to do to pass the course ...

Description

Lab 8 Aspirin Synthesis Sample Report/Data Sheet Part I. Synthesis of Aspirin 1. Mass of Salicylic acid (g) 2. Odor after addition of water 3. Mass of dried product (g)

___2.92 g__________________ ___sharp, like vinegar________ ___3.46 g_________________

4. Calculate the maximum amount of aspirin(C9H8O4) in grams that can be made from the amount of salicylic acid (C7H6O3) that you used. This is known as the theoretical yield of the reaction. The chemical equation shown in the introduction tells us that there is a 1:1 ratio between the moles of salicylic acid we start with and the amount of aspirin produced. This means that for every one mole of salicylic acid (C7H6O3) we start with, we should produce one mole of aspirin (C9H8O4). In order to calculate the theoretical yield, first convert the grams of salicylic acid (C7H6O3) to moles (Remember gram to mole conversions from Chapter 3!). This amount of moles is equal to the amount of moles of aspirin that should be produced (since it is a 1:1 ratio). Then convert the moles of aspirin(C9H8O4) to grams of aspirin and this is your theoretical yield. 2.92 g salicylic acid 180.157 g aspirin 1 mol aspirin 1 mol salicylic acid = 3.81 g aspirin × × × 1 mol aspirin 138.121 g salicylic acid 1 mol salicylic acid 1

Theoretical Yield of aspirin _____3.81 g ______________(g) 5. Calculate the percent yield for your reaction by dividing the mass of the dried product by the theoretical yield that you calculated above and multiplying by 100. Show your work below. Percent Yield_____90.8%________________________ 3.46g × 100% = 90.8% 3.81g Part II. Iron (III) Chloride Test for salicylic acid Substance

Color

Presence of Salicylic Acid (+/-)

Salicylic Acid

Purple

+

Store brand aspirin

Yellow

–

Synthesized aspirin

yellow

–

Post-lab Sample Answers

1

1. Draw the structure of aspirin below. Circle and name the functional groups present in aspirin.

2. Thinking about the three reagents (Look at procedure Step 3) you used to synthesize aspirin, which one was present in order to catalyze the reaction? Both the salicylic acid and the acetic anhydride were reactants. The phosphoric acid (H3PO4) was used to catalyze the reaction. 3. Taking more than 150mg/kg of aspirin can be fatal. For an adult who weighs 150 lbs, how many tablets (1 tablet = 325 mg of aspirin) is this? (Hint: 1 kg = 2.205 lbs) 150 lb 1 kg 150 mg aspirin 1 aspirin tablet = 31.4 tablets, 31 with 2 SF × ×( )× 325 mg aspirin 1 2.206 lb 1 kg body wt

4. What was the percent yield of aspirin in your experiment? Describe an experimental error that could explain why your yield was too high or too low.

The 91% yield is pretty good. There are many places where we may have lost some of our product: 1) when we transferred the crystals from the flask into the filter funnel, 2) some of the crystals stuck to the paper filter itself, and 3) some of the aspirin may have been dissolved in the cold water that was removed during the filtration. We noticed that the liquid that came through the funnel was cloudy after a while.

2...