# National Open University Exam Past Question – CHM 306 OCTOBER/NOVEMBER 2014 EXAMINATION

NATIONAL OPEN UNIVERSITY OF NIGERIA

1416 AHMADU BELLO WAY, VICTORIA ISLAND LAGOS SCHOOL OF SCIENCE AND TECHNOLOGY OCTOBER/NOVEMBER 2014 EXAMINATION

CHM 306:                              INSTRUMENTAL METHODS OF ANALYSIS TIME:                                    2 HOURS

QUESTION ONE

1. a) Describe the electromagnetic radiation                                      ( 10 marks)
2. b) Differentiate between the following
 i) Electronic spectroscopy ii)   iii) Vibrational spectroscopy Rotational spectroscopy (71/2 marks)

QUESTION TWO

1. a) Explain how the concentration of a coloured sample can be estimated  by colorimetry

(101/2 marks)

1. b) State the uses of Infra red Spectroscopy                                                                    (3 marks)
2. c) Distinguish between light rays and X- rays                                                                 ( 4 marks)

QUESTION THREE

1. a) Explain the basic concept of X-ray diffraction ( 7 marks) bi)   State and show mathematically Beer  and Lambert’s law                                               ( 7 marks) ii)   Calculate the concentration of a sample solution whose absorbance and molar  absorptivity at

270nm is 1.92 and 19400 respectively.                                                                                  (3 ½ marks)

QUESTION FOUR

1. a) What happens when  infra red radiation of a characteristic frequency  interacts with a molecule

(6 marks)

1. b) i) Distinguish between finger print region and group frequencies (6 ½ marks) ii) Using the relationship between the energy, frequency and wavelength of the electromagnetic radiation, compare the energy and wavelength of X-rays to that of  radiowaves            ( 5 marks)

QUESTION FIVE

1. a) Explain briefly Polagraphy ( 4 ½ marks)

1. b) i) What information can be obtained from measuring the refractive index of a compound using a refractometer (6 marks)
2. ii) Describe how the refractive index of a compound can be determined using a refractometer

(7 marks)

QUESTION SIX

1. a) Explain the basic concept of conductimetry                                                                         ( 7 marks)
2. b) Draw a schematic diagram of a spectrophotometer and state the function of the parts of the spectrophotometer sketched (10 ½ marks)
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