The following information is to be used for the next two questions. Molar absorptivity data for the cobalt and nickel complexes with 2,3-quinoxalinedithiol are eco = 36400 and ENI = 5520 at 510 nm and eco = 1240 and e Ni = 17500 at 656 nm. A 0.322-g sample was dissolved and diluted to 150.0 mL. A 25.0-mL aliquot was treated to eliminate interferences; after addition of 2,3- quinoxalinedithiol, the volume was adjusted to 50.0 mL. This solution had an absorbance of 1.129 at 510 nm and 0.305 at 656 nm in a 1.00-cm cell. Calculate the concentration of cobalt (in ppm) in the initial solution prepared by dissolving the sample. 132 This problem is based on the additivity of absorbances. Set up an expression for the total absorbance at one wavelength due to both absorbing species; do the same for the other wavelength. You now have two simultaneous equations consisting of two unknowns. Because you are given a molar absorptivity, your concentration will be in molarity; you must convert to ppm. Because you are asked for the concentration of the initial solution, the size of your initial aliquot is not relevant, but if you dilute that initial aliquot during sample processing, a compensatory factor must be used in your computation. Submit Answer Incorrect. Tries 1/99 Previous Tries Calculate the concentration of nickel (in ppm) in the initial solution prepared by dissolving the sample. 132 Submit Answer Incorrect. Tries 1/99 Previous Tries
The following information is to be used for the next two questions. Molar absorptivity data for the cobalt and nickel complexes with 2,3-quinoxalinedithiol are eco = 36400 and ENI = 5520 at 510 nm and eco = 1240 and e Ni = 17500 at 656 nm. A 0.322-g sample was dissolved and diluted to 150.0 mL. A 25.0-mL aliquot was treated to eliminate interferences; after addition of 2,3- quinoxalinedithiol, the volume was adjusted to 50.0 mL. This solution had an absorbance of 1.129 at 510 nm and 0.305 at 656 nm in a 1.00-cm cell. Calculate the concentration of cobalt (in ppm) in the initial solution prepared by dissolving the sample. 132 This problem is based on the additivity of absorbances. Set up an expression for the total absorbance at one wavelength due to both absorbing species; do the same for the other wavelength. You now have two simultaneous equations consisting of two unknowns. Because you are given a molar absorptivity, your concentration will be in molarity; you must convert to ppm. Because you are asked for the concentration of the initial solution, the size of your initial aliquot is not relevant, but if you dilute that initial aliquot during sample processing, a compensatory factor must be used in your computation. Submit Answer Incorrect. Tries 1/99 Previous Tries Calculate the concentration of nickel (in ppm) in the initial solution prepared by dissolving the sample. 132 Submit Answer Incorrect. Tries 1/99 Previous Tries
Principles of Instrumental Analysis
7th Edition
ISBN:9781305577213
Author:Douglas A. Skoog, F. James Holler, Stanley R. Crouch
Publisher:Douglas A. Skoog, F. James Holler, Stanley R. Crouch
Chapter14: Applications Of Ultraviolet-visible Molecular Absorption Spectrometry
Section: Chapter Questions
Problem 14.19QAP
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Transcribed Image Text:The following information is to be used for the next two questions. Molar absorptivity data for the cobalt and nickel complexes with 2,3-quinoxalinedithiol are eco = 36400 and eni = 5520 at 510 nm
and eco = 1240 and e Ni = 17500 at 656 nm. A 0.322-g sample was dissolved and diluted to 150.0 mL. A 25.0-mL aliquot was treated to eliminate interferences; after addition of 2,3-
quinoxalinedithiol, the volume was adjusted to 50.0 mL. This solution had an absorbance of 1.129 at 510 nm and 0.305 at 656 nm in a 1.00-cm cell.
Calculate the concentration of cobalt (in ppm) in the initial solution prepared by dissolving the sample.
132
This problem is based on the additivity of absorbances. Set up an expression for the total absorbance at one wavelength due to both absorbing species; do the same for the other wavelength. You now
have two simultaneous equations consisting of two unknowns. Because you are given a molar absorptivity, your concentration will be in molarity; you must convert to ppm. Because you are asked for
the concentration of the initial solution, the size of your initial aliquot is not relevant, but if you dilute that initial aliquot during sample processing, a compensatory factor must be used in your
computation.
Submit Answer
Incorrect. Tries 1/99 Previous Tries
Calculate the concentration of nickel (in ppm) in the initial solution prepared by dissolving the sample.
132
Submit Answer
Incorrect. Tries 1/99 Previous Tries
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