INSTRUMENTAL ANALYSIS
MIDTERM-II  ( 10.05.2007 )

1. Why can we determine all of atoms, that absorb light by fluorescence measurement, but can not determine all molecules by fluorescence?
2. Why the atomic emission spectroscopy (AES) are used in metal and mining industry more than other spectroscopic methods like molecular absorption and AAS or AFS (atomic absorption or atomic fluorescence spectroscopies) ? Explain main advantages of AES for qualitative and quantitative analysis.
3. What are the advantages and disadvantages of Raman technique compared to IR technique?
4. What kind of sources and detectors are used in IR technique?
5.a) What is chemical shift? Which factors influence chemical shift?
b) Plot the NMR spectra of following molecules;
(i) CH₃CH=CHCH₂OH (ii) CH₃OCH₂CH₃
6. Gaseous HCl exhibits an infrared peak at 2890 cm⁻¹ due to the hydrogen/chlorine stretching vibration.
a) Calculate the force constant for the bond.
b) Calculate the wavenumber of the absorption peak for DCl assuming the force constant is the same as that calculated in part (a).
( H = 1, Cl = 35.5, D = 2 )
7. What are the advantages and disadvantages of ICP torches to others excitation sources that are used in AES?