Notes
Post-Lab Questions
- What color of light shows the maximum absorbance by the dye? What color of
light shows the smallest absorbance by the dye?
- Compare the absorbance spectra data in parts 1 and 2. Does the data
demonstrate Beer’s Law? Explain why or why not?
- If you accidentally left a fingerprint on the cuvette when measuring the
absorbance of the unknown diluted solution, how would that impact your
determination of the concentration of the unknown? Explain your answer.
- Why do we measure at the wavelength of maximum absorbance when
preparing the calibration curve and not the wavelength of minimum
absorbance?
- What parts of UV-Vis absorption spectroscopy did you find most difficult? We
will be using this technique again the next two weeks. What tips/tricks do you
want to make sure to remember or get additional help with for the next lab?
References
Sigman SB and Wheeler DE. “The Quantitative Determination of Food Dyes in
Powdered Drink Mixes. A High School or General Science Experiment.” Journal of
Chemical Education, 2004, 81: 1475–1478. DOI: 10.1021/ed081p1475.
Thermo Scientific “Food Dyes and Beer’s Law” Lesson Plan, 2019, FL53099,
https://assets.thermofisher.com/TFS-Assets/MSD/Scientific-Resources/FL53099-
food-dyes-beers-law-qc-lesson-plan.pdf Accessed December 13, 2022.
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