Analytical Chemistry Test with Multiple Choice Questions
CHEM 4183 Exam #2 Name:________________________
March 11, 2013
I. Multiple Choice (3 pts each)
Choose the best answer and write it to the left of the problem number in the space provided.
1. What is a particular advantage of graphite furnace atomic absorption over flame atomic absorption?
(a) higher temperature (b) lower S/N
(c) less interference (d) small sample amounts
2. In atomic emission spectroscopy, it is desirable to have a high concentration of the element in the form of:
(a) atoms in the ground state (b) atoms in the excited state (c) ions (d) atoms as compounds
3. Which of the following atomic methods generally provide the best limit of detection?
(a) Graphite furnace AAS (b) ICP-AE (c) FAAS (d) ICP-MS
4. What is the desired bandwidth at fwhm from a source for UV/VIS absorption?
(a) 1/6 (b) 1/10 (c) 1/8 (d) 1/3
5. What is the fluorescence quantum yield (Fl) of a molecule excited into the first excited singlet state S1 followed by fluorescence from S1S0? The deactivation constants for the observed processes are: kFl = 2.0 X 108 s-1, kisc = 2.0 X 108 s-1, kec = 5.0 X 107 s-1. ki, kpd, and kd are negligible.
(a) 1 (b) 0.80 (c) 0.64 (d) 0.44
6. Which of the following generally provides the best detection limits?
(a) phosphorescence (b) fluorescence (c) absorbance (d) scattering
7. Which absorption transition is the most common used in the UV/Vis region?
(a) -* (b) -* (c) n-* (d) -*
II. Clearly and concisely answer the following. Use diagrams when applicable. (13 pts each)
1. (a) Discuss the relative advantages and disadvantages of flame atomic absorption spectrophotometry (FAAS) versus inductively-coupled plasma atomic emission (ICP-AE). (b) Which of these techniques would be best for monitoring the trace level (ppb) accumulation of toxic metals in fish, and why?
2. Describe and illustrate
March 11, 2013
I. Multiple Choice (3 pts each)
Choose the best answer and write it to the left of the problem number in the space provided.
1. What is a particular advantage of graphite furnace atomic absorption over flame atomic absorption?
(a) higher temperature (b) lower S/N
(c) less interference (d) small sample amounts
2. In atomic emission spectroscopy, it is desirable to have a high concentration of the element in the form of:
(a) atoms in the ground state (b) atoms in the excited state (c) ions (d) atoms as compounds
3. Which of the following atomic methods generally provide the best limit of detection?
(a) Graphite furnace AAS (b) ICP-AE (c) FAAS (d) ICP-MS
4. What is the desired bandwidth at fwhm from a source for UV/VIS absorption?
(a) 1/6 (b) 1/10 (c) 1/8 (d) 1/3
5. What is the fluorescence quantum yield (Fl) of a molecule excited into the first excited singlet state S1 followed by fluorescence from S1S0? The deactivation constants for the observed processes are: kFl = 2.0 X 108 s-1, kisc = 2.0 X 108 s-1, kec = 5.0 X 107 s-1. ki, kpd, and kd are negligible.
(a) 1 (b) 0.80 (c) 0.64 (d) 0.44
6. Which of the following generally provides the best detection limits?
(a) phosphorescence (b) fluorescence (c) absorbance (d) scattering
7. Which absorption transition is the most common used in the UV/Vis region?
(a) -* (b) -* (c) n-* (d) -*
II. Clearly and concisely answer the following. Use diagrams when applicable. (13 pts each)
1. (a) Discuss the relative advantages and disadvantages of flame atomic absorption spectrophotometry (FAAS) versus inductively-coupled plasma atomic emission (ICP-AE). (b) Which of these techniques would be best for monitoring the trace level (ppb) accumulation of toxic metals in fish, and why?
2. Describe and illustrate