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Analytical Separations Question Paper

Analytical Separations

Course:Master Of Science

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 314: ANALYTICAL SEPARATIONS
DATE: Tuesday, 29th December, 2009 TIME: 2.00 p.m. – 4.00 p.m.
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INSTRUCTIONS:
Answer ALL the questions.
1. a) Explain why separation is important in analytical chemistry
(4 marks)
b) What are the ways in which extraction of metals ions using solvent
extraction can be improved? Explain two ways. (4 marks)
c) How can a solute with low solubility in an organic solvent be completely
extracted into the organic layer? (3 marks)
d) A 50mls volume of water containing 0.1 g of analyte X was extracted with
25mls of hexane. If the distribution ratio was 85, how much was extracted
using 25mls of hexane at once? How much would be extracted if 5 mls
portions were used five times to extract the analyte? (6 marks)
e) i) Why is ion exchange chromatography a better separation method
for metal ions than chemical methods? (4 marks)
ii) Briefly explain three factors that influence selectivity of ions in ion
chromatography and the conditions necessary for the selectivity to
be observed (6 marks)
Page 2 of 3
2. a) Explain three factors that influence column efficiency in column
chromatography (6 marks)
b) Compare and contrast paper chromatography and thin layer
chromatography (5 marks)
c) A chromatogram of a mixture of two compounds X and Y give the
following data:
Solute Retention time (minutes) Peak width at base (minutes)
X 5.4 0.89
Y 14.3 0.75
Mobile phase 1.3
If the column length was 25 cms, Calculate
i) Number of theoretical plates for each compound.
ii) The theoretical plate height for each peak.
iii) The resolution of the column.
iv) The selectivity factor of the column
(6 marks)
d) Briefly explain the mechanisms of dialysis as a separation technique
(5 marks)
3. a) What factors influence the mobilities of ions and thus separation in
capillary electrophoresis (5 marks)
b) Explain the basis of supercritical fluid chromatography. What are the
advantages and disadvantages of supercritical fluid chromatography over
conventional chromatography? (5 marks)
c) You are given a mixture of polar organic compounds. Briefly explain the
technique that you would choose to separate and identity the component of
the sample. Explain why you would choose the technique, the conditions
necessary for separation and how the compounds will be identified.
(5 marks)
Page 3 of 3
d) Define the following terms:
i) Elution
j) Reverse phase chromatography
k) Retention volume
(6 marks)

Analytical Separations Question Paper

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