Advanced Analytical Chemistry (Chem 7595)
Homework problems for Lecture 3, Optical Electronic Spectroscopy 1 (Due 6-Feb-2008)
Problem 8-9: For Na atoms and Mg+ ions (see Figure 8-1), compare the ratios of the number of ions in the 3p excited state to the number in the ground 3s state in
(a) a natural gas-air flame (1800 K)
(b) a hydrogen-oxygen flame (2950 K)
(c) an inductively-coupled plasma source (7250 K)
(Please note - the 6th edition of the textbook contains a typographical error in problem 8-9. It refers to sodium ions, but should actually refer to sodium atoms to correctly link up with Figure 8-1. Please use sodium atoms in you calculations).
Problem 10-2: Why are atomic emission methods with an ICP source better suited for multielement analysis than are flame atomic absorption methods?
Homework problems for Lecture 4, Optical Electronic Spectroscopy 2 (Due 11-Feb-2008)
Problem 13-6: A solution containing 5.24 mg/100 mL of A (molecular weight 335 g/mol) has a transmittance of 55.2% in a 1.50 cm cell at 425 nm. Calculate the molar absorptivity at this wavelength.
Problem 13-13: Describe the differences between the following items and list any particular advantage possessed by one over the other:
(a) hydrogen and deuterium discharge lamps as sources for UV radiation
(b) filters and monochromators and wavelength selectors
(c) photovoltaic cells and phototubes and detectors for electromagnetic radiation
(d) photodiodes and photomultiplier tubes
(e) double-beam-in-space and double-beam-in-time spectrophotometers
(f) spectrophotometers and spectrometers
(g) single-beam and double-beam instruments for absorbance measurements
(h) conventional and multichannel spectrophotometers
Homework problems for Lecture 5, Rotational and Vibrational Spectroscopy (Due 18-Feb-2008)
Problem 16-7: Indicate whether the following vibrations are active or inactive in the IR spectrum (and please see the lecture notes to check your answers!)
Problem 18-2: Why does the ratio of anti-Stokes to Stokes line intensities increase with sample temperature?
Homework problems for Lecture 6, X-ray Spectroscopy (Due 25-Feb-2008)
Problem 12-2: What minimum x-ray tube voltage would be needed to excite the K-beta and L-beta series of lines for the elements (a) U, (b) K, (c) Rb, (d) W?
(Hint: see the discussion on pg. 304-305, the Duane-Hunt equation 12-1, and table 12-1).
Problem 12-9: Calculate the goniometer setting in terms of 2-theta required to observe the K-alpha-1 lines of Fe (1.76 angstroms), Se (0.992 angstroms), and Ag (0.497 angstroms), when the diffracting crystal is (a) topaz, (b) LiF and (c) NaCl.
(Hint: use equation 12-6, and table 12-3. Presenting your results as a table might help.)
Homework problems for Lecture 7, Nuclear Magnetic Resonance (Due 10-Mar-2008)
Problem 19-10: Why is carbon-13 to carbon-13 spin-spin splitting (J-coupling) not readily observed in the 1D 13C spectra of ordinary organic compounds?
Problem 19-15: How will DE for an isolated carbon-13 nucleus compare with that for an isolated proton (hydrogen-1) nucleus?
Homework problems for Lecture 10, Mass Spectrometry and Related Techniques (Due 19-Mar-2008)
If you read March’s paper on ion traps:
What is resonant excitation? Summarize how resonant excitation is used in typical ion trap MS experiments.
If you read the Russell and Edmondson paper on MALDI-TOF and accurate mass:
Summarize the advantages and disadvantages of MALDI-TOF (with DE and reflection) versus FTICR (including ESI-FTICR), especially in biochemical applications.
If you read the Aeberold and Goodlett proteomics paper:
Why is MS used so heavily in the study of post-translational modifications? Briefly describe an application to phosphopeptide sequence determinations.
If you read the Sleno and Volmer ion activation methods paper:
Pick any two of the ion activation processes described in the paper (e.g. in Table 1), describe how it works and the approximate energies involved, and list one advantage.
Answers to Homework Problems:
Homework for Lecture 3 and 4, Optical Electronic Spectroscopy
Homework for Lecture 5, Rotational and Vibrational Spectroscopy
Homework for Lecture 6, X-ray Spectrometry
Homework for Lecture 7, Nuclear Magnetic Resonance
Homework for Lecture 13, Classical and Thermal Methods