Aspirin Analysis Homework Problem Set

Goal:

Objectives:

• Students will determine the expected wavelengths to use for analysis in the aspirin laboratory experiment.
• Students will determine the effect of pH on the solubility of Iron-III.
• Students will be able to explain the chemical reactions used for the analysis of aspirin

Introduction:

UV/VIS absorption Questions:

1. Compare and contrast the method found in ac60055a008.pdf with the method found in jce_266.pdf. What is different about the sample preparation and what is different about the information obtained?
2. Explain the significance of the discussion in ac_1967_39_414.pdf on your experimental results for this experiment.

Iron Complex UV/VIS absorption Questions:

1. In the United States Phamracopeia Method the tablet is boiled for 5 minutes prior to adding the ferric chloride solution, why? In other methods sodium hydroxide is added, why? What is the significance of this reaction step.
2. The absorbance is measured at 365 nm in some methods and at 540 nm in others, Why? One method mentions the isobestic point, what is this?
3. The pH is adjusted in this experiment, find the solubility of iron-III at pH 1, 3, 4, and 5 explain what pH is required for the experiment.

Fluorescence Questions:

1. The fluorescence method described in ac60288a032.pdf does not use water as a solvent. Why?
2. What is the effect of acids on the fluorescence method described in ac60317a029.pdf?
3. The fluorescence method discussed in the Journal of Chemical Education includes a hydrolysis step. Why?

Scott Van Bramer
Department of Chemistry
Widener University
Chester, PA 19013

© copyright 1996, S.E. Van Bramer
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Last Updated: February 12, 2007