## Past Questions: CHM309 - Organic Spectroscopy

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Jed
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### Past Questions: CHM309 - Organic Spectroscopy

OCTOBER/NOVEMBER 2014 EXAMINATION
CHM 309 – ORGANIC SPECTROSCOPY Instruction- Answer any four
questions Time- 2hours

(speed of light =3.0 x 108 ms-1, plancks constant = 6.626 x10-34 Js

1ai. What do you understand as; I. Radiation 2mks
1. Chromophore 2mks
1. b. Calculate the frequency of the number of peaks passing through a given
point per second, if the wavelength between the peaks is 4 x104m. 6.5mks
1. Write short notes on the following: i. Spectroscopy 2mks
ii .Absorbance of UV/VIS radiation 2mks iii. Bathrochromic shift 2mks

2ai. A radiation has an energy of 6.4 x 1012 .Calculate the wavelength? 10.5mks
1. b. Identify each parameter in this Beer Lambert Law equation. Log Io/It =A=
εbc 4mks

1. Briefly discuss the factors determining the absorption of radiation in the UV
/VIS
1. Explain the terms, partition co-efficient and solubility of a drug. 6.5mks

4ai.Discuss the factors determining the intensity and energy level of absorption
in IR –
spectroscopy.10mks
1. List and explain two of the major components of UV- VIS
spectrometer.7.5mks

5ai. Differentiate between a dispersive and fourier transform instruments.2mks
1. Using a calibration curve show a solution that obeys Beer lambert law and
one that does not. 4mks
1. c. Discuss the three methods of sample preparation for an IR –spectromete
11.5mks

6a. Define the term mass spectrometry. 2.5mks
1. Discuss the methods of sample ionization. 15mks

Past Questions: CHM309 - Organic Spectroscopy

Jed
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### Re: Past Questions: CHM309 - Organic Spectroscopy

SCHOOL OF SCIENCE AND TECHNOLOGY October, 2013 Examination
COURSE CODE: CHM309
COURSE TILE: ORGANIC SPECTROSCOPY
INSTRUCTION: ATTEMPT ANY FOUR QUESTIONS TIME:
2HOURS

1. 1. (a) Discuss the instrumentation in UV/Vis spectroscopy. (4½ marks) (b)
List the factors governing the absorption of radiation in the UV/Vis
region (4 marks) (c) Calculate the concentration of the solution of compound
X, in moles dm-3, if the concentration
of a solution of the compound X is 2.4 x 10-2 mg cm-3, and the molar mass of X is
120 g mol-1? (4 marks) (d) Calculate the absorbance at λmax 263 nm, if the
molar absorptivity (ε), of the molecule with
concentration 9.54 x 10-5 mol dm-3 is 13102.73 dm-3 mol-1
cm-1. (4 marks)

1. 2. (a) Two organic compounds X and Y both have absorption maxima at
NOUNPORTAL.COM.NG
255 nm and 330 nm. For a pure solution of X, ε(255) = 4.60; ε(330) = 0.46. Also for a pure solution of Y,
ε(255) = 3.88; ε(330) = 30.0.
For a mixture of X and Y in a 0.01 m cell, A(255) = 0.274 and A(330) = 0.111.
Calculate the concentrations
of X and Y in the
mixture.
(8½ marks) (b) List two applications of UV/Vis
spectroscopy. (4 marks)
(c) Discuss the factors determining the intensity and energy level of absorption in
IR Spectroscopy. (5 marks)

1. 3. (a) Describe the Infra-red Spectrum. (5½ marks) (b) List the uses of
Infra-red
Spectroscopy
marks) (c) Explain one of the uses listed in 3b above
in (6 marks)
(6

1. 4. (a) Explain the principles of Mass Spectroscopy. (6½ marks) (b) What is
a molecular
ion?
(2½ marks) (c) What is the base
peak?
(2½ marks) (d) Discuss Chemical Ionization in mass
spectroscopy. (6½ marks)

1. 5. (a) Choose any five functional groups and explain their fragmentation
pattern (10 marks) (b) What is GCMS
MS.
(3½ marks) (c) Discuss the ionization techniques used in
GC-(4 marks)

1. 6. (a) Highlight the main components of a typical NMR spectrometer (8
marks) (b) Explain the general guideline to 1H-NMR spectra
interpretation. (9½ marks

Jed
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### Re: Past Questions: CHM309 - Organic Spectroscopy

COURSE CODE: CHM 309
COURSE TITLE: ORGANIC SPECTROSCOPY
TIME ALLOWED: 2 hrs

1. (a) Discuss electronic excitation in UV-Vis radiation in terms of occurrence,
types and selection rule.
(b) State the Beer-Lambert’s law.
(c) Calculate the concentration of a solution of compound X with a
molar absorptivity of
12500 M-1 dm cm-1 and absorbance of 2.5 at λmax of 465 nm
(d) What is the concentration (in mg/mL) of the solution in 1c above, if the
molar mass of
X is 120 g/mol?

1. (a) With the aid of a diagram, highlight the types of vibrational mode as in
methylene group. (b) The intensities of absorption bands in Infrared
Spectroscopy may be expressed as transmittance (T) or absorbance (A); Give the
formula for transmittance, and show the relationship between A and T.
(c) Highlight the application of Infra-red spectroscopy.

1. (a) With the aid of a diagram, give a detailed description of a mass
spectrometer. (b) List the types of mass analyzers.
(c) Choose one of the listed analyzers and discuss in details.

1. (a) Discuss the fragmentation pattern of alkanes.
(b) Highlight the rules used in the interpretation of mass spectra.

1. (a) List the molecular formulae of compounds with relative molar mass of
44.
Identify the compound if the accurate m/z value for the molecular ion determined
by high resolution mass spectrometry is 44.0262. The compound may contain
any of the following
elements: C, H, N, O.
(b) Discuss the general approach to interpretation of 13C-NMR Spectra

1. (a) The number of orientations or number of magnetic quantum states is a
function of the physical properties of the nuclei. Discuss.
(b) Write a short note on chemical shift.