Spectroscopy Homework Problem Set #2c
This problem set was developed by S.E. Van Bramer for Chemistry 366 at Widener University.
Questions are based on Skoog, West & Holler An Introduction to Analytical Chemistry. Some questions and data are based upon information from this textbook.
- What is the wavelength of the maxium emission for a blackbody radiator at 2800 K? At 3500 K? What type of source can operate at this temperature? If the bulb has a filliment that is 10 inches long with a radius of 0.05 mm, what is the total energy output?
- Compare and contrast the following instrument components. (This means, discuss the advantages and disadvantages of each in YOUR own words. DO NOT explain how they work.):
- Hydrogen discharge and deuterium discharge lamps
- dispersive and diode array spectrometers
- photodiode and photomultiplier
- filter and monochrometer
- Compounds A and B have the following molar absorbtivities. Graph the absorption spectrum for a solution that is :
- 6.78 x 10-4M in A with a 1.00 cm cell.
- 5.43 x 10-4M in B with a 1.00 cm cell.
- 6.78 x 10-4M in A and 5.43 x 10-4M in B and with a 1.00 cm cell.
- If a solution has an absorbance of 0.360 at 540 nm in a 1.00 cm cell, what is the concentration of B if the concentration of A is 5.00 x 10-4M?
|Wavelength (nm)||A (M-1 cm-1)||B (M-1 cm-1)|
- A pH indicator has a different molar absorbtivity at 450 nm for the two different forms. When the pH is 1, a 8.00x10-5M solution of the indicator has an absorbance of 0.758 in a 1.00 cm cell. When the pH is 13, this same solution has an absorbance of 0.076 in a 1.00 cm cell. if pKa = 4.92 for this indicator, what is the absorbance when the pH is 4.92? Clearly state any simplifying assumptions that you make.
- Phenanthrene is a highly fluorescent PAH (Polycyclic aromatic hydrocarbon) with an excitation maximum at 250 nm and an emission maximum at 370 nm. Results for a set of standards are given below.
- Construct a calibration curve for Phenanthrene
- Calculate the slope and intercept for the linear regression
- Calculate the standard deviation of the slope, the standard deviation of the intercept, and the standard deviation about the regression.
- Calculate the concentration of an unknown with a signal of 2.1562.
- Calculate the relative standard deviation for the concentration of the unknown.
- Calculate the relative standard deviation for the concentration of the unknown if it is the average of 4 measurements.
Please send comments or suggestions to firstname.lastname@example.org
Scott Van Bramer
Department of Chemistry
Chester, PA 19013
© copyright 1996, S.E. Van Bramer
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Last Updated: Friday, January 09, 1998 11:15:31