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CHRIST UNIVERSITY, BANGALORE-560029End Semester Supplementary Examination March - 2014

Bachelor of Technology

Code : CH132 / CH232 Max. Marks : 100

Sub : ENGINEERING CHEMISTRY Duration : 3Hrs

General Instructions : Missing data if any may suitably be assumed.Draw neat sketches wherever necessary.

Answer ALL questions. 5 X 20 = 100

1 a Write a short note on the influence of the structure of hydrocarbons on the octane number of a fuel.   (10)

  b Explain the formation of electron - hole and recombination in a diode.   (5)

  c Define doping and explain the synthesis of elemental silicon is prepared from silica.   (5)

[OR]

2 a Describe the physical and chemical properties of silicon with relevance to solar cells.   (10)

  b How catalytic converter reduces the pollution due to vehicle exhaust?   (5)

  c Explain the principle and process involved in the fractionation of petroleum with the help of a net diagram.   (5)

3 a Mention the construction, working and cell reaction of a Daniel cell.   (10)

  b Sketch a neat diagram and explain the construction and working of Leclanche cell.   (5)

  c Write the equation to calculate the emf of a battery using Nerst equation. Calculate the emf of the Li-Al

 battery Li (s) / Li+

 (0.15M) // Al3+

(0.1M) / Al(s) at 298K , if the standard reduction potential of lithiumelectrode is -3.05 Volts and that of aluminium electrode is -1.66Volts.

  (5)

[OR]

4 a Explain in detail the operation of a battery giving suitable diagrams. Also explain giving equations thechanges occurring while charging and discharging.

  (10)

  b Calculate the e.m.f of the cell Fe| Fe 2+|| Ag +| Ag at 298 K if standard electrode potential of Fe and Agelectrodes are -0.42 and 0.68 V respectively.

  (5)

  c Explain Helmholtz double layer for the origin of electrode potential.   (5)

5 a Write a brief note on hydrogen overvoltage and factors affecting it.   (10)

  b Write a short note on decomposition potential.   (5)

  c Explain the pretreatmet process followed prior to electroplating.   (5)

[OR]6 a Write a short note on electroplating of gold.   (10)

  b Explain the role of anodic metal coatings in corrosion control.   (5)

  c Stressed specimen undergoes corrosion at a faster rate, explain.   (5)

7 a Write a short note on liquid crystals and terms ‘positional order’ and ‘orientational order’ in liquid crystals.   (10)

  b Explain the principle and working of LCDs.   (5)

  c Write a short note on vulcanisation of rubber.   (5)

[OR]

8 a Liquid crystals play an important role of in the working of LCD's. Explain.   (10)

  b Distinguish between thermotropic and lyotropic liquid crystals.   (5)

  c Distinguish between nematic discotic and discotic columnar phases in liquid crystals.   (5)

9 a Differentiate the alkalinity determined by phenolphthalein and methyl orange.   (10)  b With relevant figures explain the variation of conductivity with volume of base added in the titration of a

weak acid with a weak base,also give reasons for the shape of the graph.  (5)

  c List the sources of heavy metals pollutants of water and its ill effects.   (5)

[OR]

10 a Write a note on potentiometric titrations.   (10)

  b How do you determine the Sulphate content in a sample of water?   (5)

  c Explain SPADNS method for the determination of fluoride content in water.   (5)

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