LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

   B.Sc. DEGREE EXAMINATION – CHEMISTRY

FIFTH SEMESTER – NOVEMBER 2010

CH 5508 – FUNDAMENTALS OF SPECTRASCOPY

 

 

 

Date : 09-11-10                     Dept. No.                                                    Max. : 100 Marks

Time : 9:00 – 12:00

 

PART – A

 

Answer ALL the Questions                                                                                          (10 x 2 = 20 marks)

 

1. Which electromagnetic radiation has wave length 1 m? Give the frequency of that

electromagnetic radiation.

2. Explain signal-noise ratio.
3. State Beer-Lambert’s Law.
4. What are chromophores and auxochromes?
5. Why water cannot be used as a solvent in IR spectral analysis?
6. How will you distinguish intramolecular hydrogen bonding from intermolecular hydrogen

bonding by IR spectroscopy?

7. Define coupling constant.
8. Why is KMnO₄(ag) coloured?
9. What is the difference between base peak and molecular ion peak?
10. If the m/e value of the molecular ion [M] is 173 and there is an [M+2] peak with equal

relative abundance, what are your inferences?

 

PART – B

 

Answer any EIGHT Questions                                                                                 (8 x 5 = 40 marks)

 

11. Distinguish between the following:
12. Absorption spectra-emission spectra.
13. Electronic energy levels-rotational energy levels.
14. Write the principle of ASS and explain its instrumentation.
15. Write the Boltzmann distribution formula and explain.
16. ‘Isotopic peaks have a rich source of information’ – Justify.
17. Enlist the factors that affect chemical shift values.
18. Explain the different types of electronic transitions.
19. Describe the various IR bands for ethyl benzoate.
20. Using NMR spectroscopy, how will you differentiate between

• 1-propanol and 2-propanol.
• Acetone and acetaldehyde.

19. Discuss mutual exclusion principle.
20. Write a note on sample handling in IR spectroscopy.
21. Can you distinguish CH₃ CH₂ OCH₃ from (CH₃)₂ CHOH by PMR Spectroscopy?
22. Explain the fragmentation pattern of n-butanol.

PART – C

 

Answer any FOUR Questions                                                                                (4 x 10 = 40 marks)

 

23. Draw the block diagram of double beam IR spectrometer and explain its components.
24. List out the difference between (i) IR and Raman spectroscopy (ii) Stoke’s and antistoke’s

lines.

25. a) What are the merits of TMS?
26. b) Discuss the basic instrumentation in NMR.
27. a) How will you determine the structure of a compound whose m/e value are 86 (molecular

ion), 57 (base peak), 29?

1. b) What are the factors that affect absorption maximum and intensity in UV-visible

spectroscopy?

27. Discuss the principle and applications of flame photometry.
28. Explain a) MCLafferty rearrangement b) high resolution NMR Spectrum of ethanol.

 

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LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

B.Sc. DEGREE EXAMINATION – CHEMISTRY

FIFTH SEMESTER – NOVEMBER 2012

CH 5508 – FUNDAMENTALS OF SPECTRASCOPY

 

 

 

Date : 08/11/2012             Dept. No.                                        Max. : 100 Marks

Time : 9:00 – 12:00

 

PART – A

 

Answer ALL questions:                                                                                           (10 x 2 = 20 marks)

 

1. Define the term resolution.
2. The wavelength of a radiation is 2.5 x 10^-6m. Calculate its frequency.
3. State Beer Lamberts’ law.
4. What are auxochromes? Give an example.
5. What are monochromators?
6. What is Rayleigh scattering?
7. Define coupling constant.
8. Define Larmour precessional frequency.
9. What is an isotopic peak?
10. What is FAB?

PART – B

Answer any EIGHT questions:                                                                               (8 x 5 = 40 marks)

 

11. Explain the terms line width and intensity of spectral lines.
12. Discuss the types of transitions in molecules.
13. Discuss the instrumentation of photocolorimeter.
14. Explain the applications of Flame photometry.
15. Discuss the differences between IR and Raman Spectroscopy.
16. Explain the source and the sampling technique in IR spectroscopy.
17. Explain the following terms:

(i) Fundamental vibration           (ii) Over tones

18. Explain the basic instrumentation of NMR spectroscopy.
19. Explain the pmr spectrum of CH₃CHO and pure CH₃CH₂OH.
20. A compound having the molecular formula C₁₀H₁₄ gave the following pmr data:

(a) A singlet 9H (d = 0.88)

(b) A singlet 5H (d = 7.28) Give the structure of the compound.

21. Describe the importance of metastable peak in mass spectral analysis.
22. Explain the mass spectrum of Benzyl alcohol.

 

PART – C

 

Answer ANY FOUR questions:                                                                              (4 x 10 = 40 marks)

 

23. a) Explain Frank-Condon principle. (6)
24. b) Benzene is colourless but its isomer, fulvene is yellow. Explain.                                            (4)

 

24. Explain the principle, instrumentation and applications of atomic absorption spectroscopy.                                            (2+4+4)

 

25. a) Discuss the theory of Raman Spectroscopy. (5)
26. b) Explain how IR spectroscopy can be used to differentiate inter and intra molecular hydrogen

bonding.                                                                                                                                        (5)

 

26. a) Explain the types of stretching and bending vibrations of CO₂.      (6)

 

1. b) Discuss Fermi-resonance.                                                                                                             (4)

 

27. a) Explain the term chemical shift. What are factors influencing it?                                              (6)
28. b) Explain deuterium labelling in NMR.                                                                                          (4)

 

28. a) Illustrate Mclafferty rearrangement with a suitable example.                             (5)
29. b) Explain the instrumentation of mass spectrometer.                                                                    (5)

 

 

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