NATIONAL OPEN UNIVERSITY OF NIGERIA
14/16 AHMADU BELLO WAY, VICTORIA ISLAND, LAGOS
SCHOOL OF SCIENCE AND TECHNOLOGY
MARCH/APRIL 2014 EXAMINATION
COURSE CODE: CHM413
COURSE TITLE: ANALYTICAL CHEMISTRY 11
TIME ALLOWED: 2HOURS
INSTRUCTION: Six questions to answer four(Each question carriers a total 17marks)
Question 1
a) Distinguish between random and systematic errors (7marks)
b) Define the following terms:
i) Random error ii) Confidence limits
iii) Accuracy iv) Precision (2mark each; total of 10marks)
Question 2
The result of the concentration of zinc metal (mg/L) in soil of a waste dump is presented as follows:
178.0 125.68 100.50147.50 111.16 95.46 143.20 98.89
Calculate:
i) Mean (3marks)
ii) Median (4 marks)
iii) Standard deviation (5 marks)
iv) The 95% confidence limits for the true mean. (5 marks)
Question 3
a) State two types of glass membrane electrode (5 marks)
b) A solution is 10-3M in Cr2O7-2 and 10-2M inCr3+. If the pH is 2.0, what is the potential of the half reaction? (8marks)
Question 4
a) Discuss the factors that affect the conductance of electrolyte solutions. (8marks)
b) Differentiate between thin layer chromatography and column chromatography. (9marks)
Question 5
Write short notes on the following:
a) Electrochemical deposition b) Particulate radiation c) Electromagnetic radiation
d) Ion exchange techniques. (4mark each; total of 17marks)
Questions 6
a)State theKohlrausch law of independent migration of ions (3marks)
b) Briefly explain the two application of Kohlrausch law of independent migration of ions (5 marks)
c) For acetic acid (HAc), Lo = 390.6 ohm-1 cm2 mol-1, while at a concentration of 0.003441 mol dm-3, L = 27.19 ohm-1 cm2 mol-1. What is the degree of disassociation, the concentration of each species, and the equilibrium constant? (9 marks)
For the 2015 – till date past questions for this course CLICK HERE
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