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National Open University Exam Past Question – MAY/JUNE 2012 EXAMINATION

NATIONAL OPEN UNIVERSITY OF NIGERIA

1416 AHMADU BELLO WAY, VICTORIA ISLAND LAGOS SCHOOL OF SCIENCE AND TECHNOLOGY

MAY/JUNE 2012 EXAMINATION

 

 

CHM 304: Colour Chemistry & Technology (2 Credit Units) Time: 2 Hours

 

INSTRUCTION: Answer any four Questions

 

1)      a)     Differentiate between organic and inorganic pigments. (10 marks)

  1. b) Using structural examples, explain the types of Betalain pigments. (5 marks)
  2. c) Enumerate  five limitations of natural  pigments. (2½ marks)

 

2)  a)  Write short notes on the followings:

  1. i) Secondary colours. (3 marks)                     ii) Tertiary colou (2½ marks)

iii) Azoic dyes   (2½ marks)                              iv) Vat dyes (2½ marks)

  1. v) Sulphur dyes (2½ marks)
  2. b) Mention seven differences between dyes and pigment  (7 marks)

 

3) a)  Explain the concept and applications of mordants for natural  dyeing.(10 marks)

  1. b) i) What is meant by the term polymerization (2½ marks)
  2. ii. Describestructurallypolymerization of monomer methyl methacrylate (5

marks)

 

4) a)   i) Define the term synthetic fibers. (3 marks)

  1. ii) Describe the various kinds of fiber (8½ marks)
  2. b) What is the role of modifiers in relation to the colour of the dye? (6 marks)

 

5) a) Describe the principle of beam dyeing machine.(7 marks)

  1. b) What are the features of beam dyeing machine? (4½ marks)
  2. c) Discuss the advantages of beam dyeing machines. (6 marks)
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6)   a) Enumerate  the advantages of overflow dyeing machines.(5 marks)

  1. b) Give three uses of the aramid (3 marks)
  2. c) What are the main chemical functional groups in both nylon and polyesters?

(3 marks)

  1. d) Mention two uses of polyurethane (2 marks)
  2. e) Structurally differentiate between the two aramids: Nomex and Kevlar (4½

marks)

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