Procedure
Raw Data
Data Processing
Titration
Cardioton Trial 1
Mass of Aspirin:0.868
Volume of NaOH:
VI=27.51 mL Vf=44.71 mL Difference: 17.2 mL
Titration Equation
0.0172L x 0.100M = 0.00172 moles of NaOH
Molar mass
C9=108.9 g
H9=9.09 g
O4=63.96 g
108.9 g + 9.09 g + 63.96 g = 181.96
181.96x
Uncertainties
Mass of aspirin: 0.868 g
Uncertainty of aspirin: ± 0.001
Volume of NaOH:
- Initial: 27.51 mL
- Final: 44.71 mL
Uncertainty of NaOH: ±0.05
Volume of Ethanol: ± 0.05
Uncertainty of aspirin:
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. Continue adding base 5.0 mL past the equivalence point
(the equivalence is approximately when the solution turned pink from the
phenolphthalein)..
9. Repeat steps 1-11 for the remaining tablets.
10. Clean lab equipment with water, and wipe the lab surface with a wet paper towel.
The pH probe should be rinsed with DI water, gently blotted dry, and put back into its
storage solution.
Place a 325 mg aspirin tablet in about 20 mL of deionized water and let stand for a few minutes. The tablet will break apart as it absorbs water and swells.
2. Add 20 mL of ethyl alcohol to dissolve the aspirin.
3. Add 3-4 drops of phenolphthalein indicator to the solution.
4. Rinse out a buret twice with deionized water, then drain 10 mL of 0.100 M NaOH.
5. Fill your buret with NaOH and record the initial volume.
6. Titrate with 0.100 M NaOH to the endpoint, the light pink color.
7. Record the final volume of the NaOH.
8. Repeat the experiment, but instead of phenolphthalein, use thymol blue as an indicator. It is not necessary to clean out your buret of NaOH before you begin the second experiment. Simply refill your buret and then begin again.
9. Clean and return all equipment used in this lab.
Trial 1 Trial 2 Trial 3
Aspirin type ______________________________________
Tablet mass before grinding ______________________________________
Tablet mass after grinding ______________________________________
Starting reading of NaOH in buret ______________________________________
Ending Reading of NaOH ______________________________________
Total Volume of Base used ______________________________________
Number moles NaOH used ______________________________________
Number of moles Acetyl salicylic
acid (C9H8O4) neturalized ______________________________________
Data Analysis: Show all work.
Cost per gram;
1. Calculate the cost per gram of each type of aspirin tested.
2. Calculate the cost per tablet of each type of aspirin tested.
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!