CM 132 — CHEMISTRY — II Question Papers

B.E./B.Tech. DEGREE EXAMINATION,
Second Semester
Mechanical Engineering
CM 132 — CHEMISTRY — II Question Papers
(Common to Mechatronics Engineering)
Time : Three hours Maximum : 100 marks
Answer ALL questions.
PART A — (10 * 2 = 20 marks)
1. State law of ‘Mass Action’. Give an example.
2. What is enthalpy of a reaction? What is the significance of its sign?
3. What are high polymers? Name any two polymers which act as a plastic and a fibre?
4. Differentiate between a simple polymer and a copolymer.
5. Differentiate between electrolytic cells and galvanic cells.
6. What are cells and batteries?
7. All ores are minerals but all minerals are not ores. — Justify.
8. What is a liquid resin?
9. What is meant by the secondary operations, coining and impregnation, as applicable to powder metallurgy?
10. List any four advantages of powder metallurgy.

PART B — (5 * 16 = 80 marks)
11. (i) How are metal powders produced by atomisation and chemical reduction process? (4)
(ii) What are the purposes of blending and mixing in powder metallurgy? What are the advantages of wet mixing and presintering? (4)
(iii) Briefly explain die–pressing and roll–pressing methods of compacting in powder metallurgy. (4)
(iv) What is meant by sintering in powder metallurgy? How is it carried out? What are the changes taking place during sintering? (4)
12. (a) (i) Write the mechanism of reaction. (6)
(ii) Classify refractories into different types and give one example for each type. (6)
(iii) Show that Gibb’s free energy is the non–mechanical work attainable from a system. (4)
Or
(b) (i) What are Ellingham diagrams? What informations can be obtained from the position and shape of Ellingham diagrams of silver, aluminium and carbon? (6)
(ii) What are the significance of the three characteristics, refractoriness, porosity and thermal conductivity, of refractories? (6)
(iii) What is condensed phase rule? What is the number of degrees of freedom at the eutectic point for a two component system? (4)
13. (a) (i) Name any four plastic moulding compounds, apart from resins, mention their functions and give one example for each. (6)
(ii) Explain the process of manufacture of glass. (6)
(iii) Name any two synthetic fibres and give their formation reactions from their monomers. (4)
Or
(b) (i) How are glazed whitewares manufactured? (6)
(ii) What are the main divisions of composite materials? Give one example for each type. Name four fillers and polymers each used in the manufacture of reinforced plastics. (6)
(iii) Differentiate between polymer blends and polymer alloys. (4)
14. (a) (i) What are the four valuable informations which can be obtained from electromotive series? (6)
(ii) What are the possible cathodic reactions at different environments, and the only anodic reaction encountered in electrochemical corrosion? (6)
(iii) How is electropolishing of stainless steel carried out? (4)
Or
(b) (i) How is aluminium extracted by, electrowinning process, from pure alumina? (6)
(ii) How is corrosion controlled by sacrificial anode and impressed current techniques? (6)
(iii) Give the general mechanism of electropolishing of metals and alloys. (4)
15. (a) (i) If ores differ from their impurities in their specific gravities and magnetic properties what concentration techniques are employed? Explain. (6)
(ii) What is meant by roasting? With a diagram of reverberatory furnace indicate the changes that occur during roasting of ZnS ore.
(6)
(iii) Discuss the sequence of steps followed in the preparation of alloys by fusion method. (4)
Or
(b) (i) Draw the phase diagram of Iron–Carbon alloy system representing that portions above solidus curve and explain the behaviour of the system pertaining to those regions only. (6)
(ii) Explain how a metal is obtained from calcined or roasted ore by smelting and further purified by electrolytic refining. (6)
(iii) What happens during carburizing and nitriding of steel? (4)