Asking for help with questions 3,4,5 2. Discuss the possible sources of error in

Question

Asking for help with questions 3,4,5

2. Discuss the possible sources of error in this experiment and how they affect the results. 3. If the reagent grade ASA used to prepare the standards was impure, would it cause the percent ASA you determined in the commercial tablet to be higher or lower? Assume the impurities were colourless and soluble. Give reasons for your answer. 4. When John Doe turned his back while preparing his unknown ASA solution, I.M. Chaos changed the wavelength setting so that the Spectronic 20 was not reading the Amax but was set on the side of the max. If John did not notice what had been done and failed to readjust the instrument, would the calculated value for the concentration of ASA in the unknown tablet be higher than, lower than, or the same as the true value? Give reasons for your answer. Remember that all of the standards were measured at max. 5) Another CHEM 1210 student, Sidney Smart, prepared all his ASA standard solutions with the level of the meniscus slightly below the mark in the volumetric flasks. Using these solutions he prepared a Beer's law plot and used it to analyze his unknown ASA sample. He obtained a result of47.9% by mass ASA in the tablet. Is the true value for the tablet higher or lower than 47.9%? Give reasons for your answer.

Explanation / Answer

3. The percent of ASA that is determined in presence of the impurities will be lower due to the interference of the impurities. Moreover as the impurities are colourless and soluble, the overall percentage determined would have contribution of both the reagent ASA and the impurities. This would be obviously less than that obtained using a pure ASA reagent.

4. This depends on which side the knob is set. The value measured will obviously be different than the true value.

5. If the candidate has prepared a solution with level lower than the mark, the concentrate of analyte would be less. So, the true value would be more than the experimental value.

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