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Spectroscopic Techniques Question Paper

Spectroscopic Techniques

Course:Bachelor Of Education

Institution: Kenyatta University question papers

Exam Year:2009

KENYATTA UNIVERSITY
UNIVERSITY EXAMINATIONS 2009/2010
FIRST SEMESTER EXAMINATION FOR THE DEGREE OF BACHELOR OF
SCIENCE AND BACHELOR OF EDUCATION
SCH 417:
SPECTROSCOPIC TECHNIQUES

DATE: Wednesday, 30th December, 2009
TIME: 11.00 a.m. – 1.00 p.m.
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INSTRUCTIONS:
Answer ALL questions.
Q.1
a)
i)
Explain what spectroscopy is as applied to chemical measurements
ii)
Instrumentation in spectroscopy contains four major optical parts arranged in single or double beam design. Using a diagram, explain the difference between a single beam and a double beam design.
iii)
Explain, by use of a diagram how a photomultiplier tube detector works. (10 marks)
b)
i)
Explain what causes a molecule to absorb radiation at the mid- infrared (IR) region of the electromagnetic spectrum.
ii)
Discuss the process of identifying an organic compound using infrared spectrum.
iii)
Explain how the constituents in a benzene ring affect its fluorescence properties. (12 marks)
c)
Explain what causes shielding and de-shielding effects in NMR. (4 marks)
Q.2
a)
A water quality chemist determined the levels of sodium in well water using flame photometry.
i)
Explain the principle of analysis used in the technique.
ii)
Explain, giving essential experimental details only, a procedure for the analysis of sodium the chemist used.
iii)
Discuss the chemical interferences experienced in this procedure and how they can be minimized. (10 marks)
b)
Write short notes on the following:-
i)
Auger electron spectroscopy
ii)
Chemical ionization in MS
iii)
Hyperfine interactions in electron spin resonance
iv)
Hollow cathode lamp
(12 marks)
Q.3
a)
Describe two ways of introducing a sample into an ICP torch. Explain why ionization interferences are less severe in ICP than in flame emission spectroscopy. (8 marks)
b)
i)
State the law of photometry and explain under what conditions it is applicable.
ii)
At 580 nm FeSCN+2 complex has a molar absorptivity of 7.00 x 103 L/mol/cm. A 50.0 ml aliquot of well water is treated with excess of KSCN and diluted to 100 ml. Calculate, the iron
(III)
ions concentration in the sample if the diluted solution has as absorbance of 0.56 nm when measured in a 1.5 cm cell. (6 marks)
c)
Using diagrams, describe how electron spectroscopy for chemical analysis (ESCA) and Auger electron spectroscopy (AES) are used in surface analysis. (8 marks)

Spectroscopic Techniques Question Paper

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