CORK INSTITUTE OF TECHNOLOGY
INSTITIÚID TEICNEOLAÍOCHTA CHORCAÍ
Autumn Examinations 2011
Module Title: SPECTROSCOPY & CHROMATOGRAPHY
Module Code:
CHEA7004
School:
Science and Informatics
Programme Title:
Bachelor of Science in Analytical & Pharmaceutical Chemistry – Year 3
Programme Code:
SCHEM_7_Y3
External Examiner(s):
Internal Examiner(s):
Dr G. Keaveney
Dr L. Goold
Instructions:
Attempt any 4 questions
Duration:
2 hours
Sitting:
Autumn 2011
Requirements for this examination:
Note to Candidates: Please check the Programme Title and the Module Title to ensure that you have received the
correct examination paper.
If in doubt please contact an Invigilator.
Q1. (a) What mass of potassium nitrate, KNO3, is contained in 400 cm3 of an aqueous solution of
KNO3 that has a concentration of 50.0 ppm K+. ( Assume the only source of K+ in the
solution is KNO3).
Relative Atomic Mass Data:- K- 39.1.0, N- 14.0, O-16.0
(4 marks)
(b)
Describe the process of soxhlet extraction of a soluble component from a solid and briefly
explain why it is such an efficient method of extraction.
(8 marks)
(c)
Describe the practical procedure involved in carrying out a recovery experiment and
explain the usefulness of such an experiment in the assessment of an analytical method
(8 marks)
Q2.
Write a detailed account on the topic of sampling. Your account should include reference to
the following:- (i) why sampling is necessary (ii)general sampling considerations (iii)
sampling of the solid, liquid and gaseous states (iv) examples of devices that are used for
sampling.
(20 marks)
Q3.
1.500 g of a solid sample, containing Fe, were dissolved in a suitable mixture of acids and,
after complete dissolution, the resulting solution was diluted to 100.0 cm3. (solution A). A
further solution, solution B, was prepared from solution A by diluting 4.0 cm3 of solution A
to 50.0 cm3. All of Solution B was then divided into five equal volume aliquots, with each
aliquot being transferred to a separate 25.0 cm3 volumetric flask. Various volumes (0.0, 2.0,
3.0, 5.0 and 7.0 cm3) of a standard solution of Fe (50.0 ppm) were added to the flasks
before each flask was diluted to the mark with water. Analysis of the resulting solutions,
using flame atomic absorption measurements, yielded the following absorbance values:0.21 (0.0 cm3 added), 0.33 (2.0 cm3 added), 0.38 (3.0 cm3 added), 0.48 (5.0 cm3 added),
0.59 (7.0 cm3 added).
PTO
Q3.(cont.)…
(a) Illustrate, by means of a block diagram, the main components of the instrument
used for obtaining the measurements and explain the manner in which the
absorbance of any one of the solutions is obtained.
(8 marks)
(b) Estimate, using an appropriate plot, the % Fe in the original solid sample.
(12 marks)
Q4.
(a) Explain the manner in which a flame ionisation gas chromatographic detector operates.
(6 marks)
(b) Describe the process of head space analysis in gas chromatographic analysis.
(6 marks)
(c) Differentiate between isothermal and temperature programmed gas chromatography.
(4 marks)
(d) Show how (i) theoretical plate value (N) and (ii) resolution (R) can be determined from
a chromatogram.
(4 marks)
Q5. Write notes on two of the following topics:(a) Usefulness of infra-red spectroscopy in qualitative analysis
(10 marks)
(b) Comparison of sensitivity and selectivity of uv-visible spectroscopy and fluorescence
spectroscopy.
(10 marks)
(c) Comparison of pre- and post- column derivatisation in HPLC analysis
(10 marks)