LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034
B.Sc. DEGREE EXAMINATION – CHEMISTRY
FIFTH SEMESTER – APRIL 2012
CH 5508 – FUNDAMENTALS OF SPECTROSCOPY
Date : 03-05-2012 Dept. No. Max. : 100 Marks
Time : 9:00 – 12:00
PART – A
Answer ALL questions: (10 x 2 = 20 Marks)
- Arrange the following spectral regions in the increasing order their frequencies (a) UV (b) IR
(c) X – ray (d) Microwave (e) cosmic rays.
- Distinguish between absorption and emission spectrum.
- Write the mathematical expression for Beer – Lamberts law.
- What is the wavelength of UV, IR regions in the electromagnetic spectrum?
- What is finger print region?
- How are CH₃CH₂COCH₃ and CH₃CH₂CH₂OH distinguished using IR spectroscopy?
- What is coupling constant?
- Why TMS is used as a reference in NMR spectroscopy?
- Define base peak.
- Name the parts of a mass spectrometer.
PART – B
Answer any EIGHT questions: (8 x 5=40Marks)
- Describe the factors that determine the intensity of spectral lines.
- Discuss various types of electronic transition with a suitable diagram.
- State and explain Frank – Condon principle.
- Discuss the instrumentation of photocolorimeter.
- Explain Rayleigh and Raman effects.
- State Mutual exclusion principle and discuss the geometry of CO₂ and N₂O.
- Write any 5 differences between IR and Raman spectrum.
- Discuss the instrumentation of NMR spectroscopy.
- Explain spin – spin coupling.
- How many signals appear in the NMR spectrum of a) toluene b) propyl alcohol c) acetone
- d) ethyl alcohol e) acetaldehyde?
- Explain nitrogen rule in mass spectrometry.
- Write notes on metastable peak.
PART – C
Answer any FOUR questions: (4×10=40 Marks)
- Explain the following terms with suitable examples.
- a) chromophore b) Bathochromic shift c) auxochrome. (10)
- Discuss the principle, instrumentation and application of flame Photometry. (10)
- a) Discuss stretching and bending vibrations. (5+5)
- b) Discuss the selection rules of Raman spectrum.
- a) Explain the sampling techniques in IR spectroscopy. (5+5)
- b) Distinguish the following using IR spectra:
- i) CH₃CH₂CHO and CH₃COCH₃
- ii) CH₃CONH₂ and CH₃NH₂
iii) C₂H₅OH and C₂H₅Cl.
- a) Explain McLafferty rearrangement. (5+5)
- b) Write notes on shielding and deshielding effects.
- a) Discuss the basic principles of mass spectrum. (5+5)
- b) Determine the structure of the compound whose m/e values in the mass spectrum
are 100, 85, 71, 57, 43(base) 41, 29 and 27.