LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034 B.Sc. DEGREE EXAMINATION – CHEMISTRY

AD 10

FIFTH SEMESTER – NOV 2006

CH 5501 – ANALYTICAL CHEMISTRY

(Also equivalent to CHE 509)

 

 

Date & Time : 27-10-2006/9.00-12.00   Dept. No.                                                       Max. : 100 Marks

 

 

 

Part A

Answer all the questions.                                                                                      10×2=20

1. Define chromophores with an example.
2. Calculate the number of photons emitted in one second from a 100W red lamp, assuming that the photons emitted by the lamp have an average wavelength of 694 nm (1W = 1 Js^-1)
3. What is Von Weirman ratio?
4. How many normal modes of vibrations possible for CO
5. Calculate the molarity of a solution, which contains 6.00g of NaCl in 200 ml of the solution.
6. What is meant by precision?
7. Calculate the relative average deviation of following set of values in titration experiment 9.8, 10.6, 10.8 and 10.4 ml.
8. Define the term absolute error.
9. What are the factors affecting the solubility product?
10. What are the various cleaning agents commonly used for cleaning glasswares?

 

Part B

Answer any eight questions.                                                                                  8×5=40

 

11. What are the requirements of a primary standard?
12. Explain quinonoid theory for phenolphthalein and methyl orange.
13. A compound of molecular weight 100 has a molar absorptivity of 1.00×10⁵ l mol^-1 cm^-1. How many grams of this compound should be present in exactly in 1 litre of the solution so that after a two hundred-fold solution, the resulting solution will have an absorbance of 0.5 in a 1 cm cell?
14. A sample of pure NaCl (MW=58.44) weighing 0.2286g is dissolved in water and exactly 50ml of AgNO₃ is added to precipitate AgCl. The excess Ag⁺ is backtitrated with 12.56ml of 0.0986N solution of KSCN. Calculate the normality of AgNO₃
15. What are the procedures employed to minimize the coprecipitation.

 

 

 

16. What is S/N ratio? How is it improved?
17. Explain the terms threshold vapor concentration and universal antidote.
18. In two separate determinations, the concentration of iron in a given sample was found to be a) 20.17 ppm b) 19.80 ppm. Taking the accepted value as 20.00 ppm, calculate the absolute error, relative error as percent and as parts per thousand in the two determinations.
19. What is R_f value? What are the factors affecting R_f value?
20. In the precipitation reaction when 0.0500M AgNO₃ is added to 25.00 ml of a solution that is 0.0150M NaCl, 0.0100M NaBr, calculate the concentration of silver ion.
21. Explain the development of chromatogram in TLC. Give its applications.
22. Write a note on normal error curve and explain its importance.

 

Part C

Answer any four questions.                                                                                 4x 10=40

 

 

23. How is UV-Visible spectrum recorded by double beam spectrophotometer?
24. What are the factors affecting e_max and l Explain with examples.
25. a) Derive Henderson equation for acidic buffer.
26. b) How is Volhard method used for the determination of chloride? (5+5)
27. a) Explain the principle of steam distillation.
28. b) Describe with diagram how a substance can be purified by this method. (5+5)
29. Explain the theory behind the separation of mixture by column chromatography. Mention its applications.
30. In a set of measurements the following concentrations of Fe (ppt) was reported:

20.21, 20.41, 20.31, 20.11, 19.91, 20.01 and 19.81.Calculate a) average deviation

1. b) standard deviation   c) relative standard deviation   d) coefficient of variation   e) range.

 

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