Titration- Analysis of Aspirin Tablets
Objective: Determine the percentage of aspirin (acetylsalicylic acid) present in two different commercial tablets by titrating the solution with a base. Also determine whether the aspirin is a strong or weak acid according to the Bronsted- Lowry and Lewis theories and deduce the formula of the acid- base reaction.
Independent Variable: The amount of base (NaOH) in moles that are needed to neutralize the solution.
Dependent Variable: Percentage of aspirin (acetylsalicylic acid) found in each tablet.
* Balance * 2 aspirin samples from different brands * 50 cm3 conical flask * 10.00cm3 of 95% alcohol * 0.100 mol dm-3 sodium hydroxide * Phenolphthalein
1. Bring samples of two different aspirin brands, note names, price, and the value of the aspirin per tablet indicated by the manufacturer. 2. Weight out accurately one tablet into a 50 cm3 conical flask and dissolve it in 10.0cm3 of 95% alcohol. 3. Titrate with 0.10 mol dm-3 sodium hydroxide solution using two drops of phenolphthalein solution as indicator in the first trial. 4. For the next trials repeat steps 1 and 2, but instead of using an indicator use an electronic pH tester to measure the pH of the solution to determine when its neutral; (PH -7) . 5. Record data, ml used in titration to neutralize every aspirin trial.
Raw Data Collection:
Aspirin A: Trial | Aspirin Tablet | Uncertainty (ml) | Burette Reading NaOH(ml) | Resulting | Uncertainty (ml) | | (Grams) | | Initial (ml) | Uncertainty(ml) | Final (ml) | Uncertainty(ml) | NaOH (ml) | | 1 | 0.598 | -+0.001gr | 13.50 | -+0.05ml | 40.60 | -+0.05ml | 27.10 | -+0.10ml | 2 | 0.603 | -+0.001gr | 11.90 | -+0.05ml | 40.80 | -+0.05ml | 28.90 | -+0.10ml | 3 | 0.599 | -+0.001gr | 9.50 | -+0.05ml | 37.40 | -+0.05ml | 27.90 | -+0.10ml | Average: | 0.600 | -+0.001gr | 11.63 | -+0.05ml | 39.60 | -+0.05ml | 27.97