How would the presence of an impurity in your unknown that absorbs at 545 and 44

Question

How would the presence of an impurity in your unknown that absorbs at 545 and 440 nm influence the accuracy of your concentration measurement (would your final result be higher or lower than the true value)? Would this impurity influence the precision of the measurement if it were constant in concentration? How many wavelengths would be required to measure concentrations of a six-component mixture? What does the slope of the calibration curve tell you about how well a compound absorbs at a given wavelength? Which of the values in the following equation arc wavelength dependent? A = epsilon b C Download an article from the journal Analytical Chemistry that uses UV-Vis and attach it to this report.

Explanation / Answer

Analytical chemistry

1. Presence of impurity that absorbs at the same wavelength as that of the required compound, would result in a value higher than the true value. Higher absorbance value would be obtained in all the cases.

2. To measure concentrations of a six-component mixture, we would require, six wavelengths.

3. Slope of the curve is molar absorptivity which relates to the efficiency of the compound to absorb at that particular wavelength. So higher is the value of the slope better is the sensitivity for that compound.

4. Wavelength dependent term is "e" which is molar absorptivity. (the middle term)

5. Article

African Journal of Pure and Applied Chemistry Vol. 5(1), pp. 1-8, January 2011

http://www.academicjournals.org/AJPAC

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