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Unformatted text preview: Problem Set Chemistry 221 1. Define absorption, absorbance, percent transmission, and transmittance. 2. Define absorptivity and molar absorptivity. 3. Describe radiation sources and detectors for the ultraviolet, visible, and infrared regions of the spectrum. 4. Describe the principles of fluorescence. Why is fluorenscence generally more sensitive than absorption mea- surements? 5. Express the wavelength 2500 Ain micrometers and nanometers. 6. The most widely used wavelength region for infrared analysis is about 2 to 15 m. Express this range in angstroms and in wavenumbers. 7. Several spectrophotometers have scales that are read either in absorbance or in percent transmittance. What would be the absorbance reading at 20% T? At 80% T? What would the transmittance reading be at 0.25 absorbance? At 1.00 absorbance. 8. A 20 ppm solution of a DNA molecule (unknown molecular weight) isolated from Escherichia coli was found to give an absorbance of 0.80 in a 2 cm cell. Calculate the absorptivity of the molecule.to give an absorbance of 0....
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- Spring '08