VTU Question Papers Engineering Chemistry Dec 2010

 VTU Question Papers Engineering Chemistry

First/Second Semester B.E. Degree Examination, December 2010

 

Time: 3 hrs.                                                                                                    Max. Marks:100

Note: 1. Answer any FIVE full questions, choosing at least two front each part.

2. Answer all objective type questions only on OMR sheet page 5 of the answer booklet.

  1. Answer to objective type questions on sheets other than OMR will not be valued.

PART-A

1 a. Select the correct answer:

i)          The tendency of knocking is more in     hydrocarbons.

A) Aromatic    B) Straight chain C) Olefins   D) Cyclic

ii)        Catalyst used in fluidized-bed catalytic cracking is

A) Z1O2 + Ce(>2                   B) AI2O3 + Fe2C>3

C) Fluidized AI2O3 and Si02      D) AI2O3 + Ce02

iii)      Petrol obtained from petroleum oil is subjected to reforming because

j A) To remove impurities and water B) For structural modification C) For deg -adation of high mol. weight hydrocarbons D) To reduce weight.

iv)      ….. ji nction is used in the conversion of solar energy into electrical energy.

>      B)n-p-n            C)p-n       D) none of these. (04 Marks)

gross calorific value of a fuel. Describe how calorific value of a solid sample

(07 Marks)

 

       Calculate the gross calorific of a sample of coke from the following data:

Mass of coRe: 0.73×10′3kg Water equivalent of the calorimeter: 0.328 kg

Mass of water: 1.25 kg                          Specific heat of water: 4.187 kJ kg^K’1

Rise in temperature: 1.9 K.                                                                                                       (04 Marks)

Select the correct answer:

i)       Glass electrode can not be used in the presence of fluoride ions because A) alkaline error         B) loss its activity

C) glass membrane dissolves                                D) leads to asymmetric potential.

ii)     The value of EMF is ………………………………….  , if AG = -212.3 kJ/mol, T = 298 K and

Faraday constant = 9.65 kJ/V/mol.

C) 2.2 V                          D) 22.0 V

 

iii)      EMF of a cell mainly depends on

A)    Size of the cell

C)    Weight of the cell

B)     Quantity of the electrolyte

D)     Difference between Ecathode and Eanode.

iv) Use of secondary reference electrode is preferred over primary reference electrode becasue

A) it is light weight          B) it is compact

C)    it is reversible with electrolyte ‘ D) it gives constant and reproducible potential.

(04 Marks)

  1. tyhat are ion-selective electrodes? Explain the principle, construction and working of a gla electrode.              (W Vlark

«=»

c– Derive the Nemst equation for a single electrode. Write Nemst equation for the given cell:

Cu (s) |:GU2+ (aq) 11 Ag+ (aq) | Ag                      (05 Mark

d. Calculate E^?t/Zn, if the emf of Zn | Zn2+ (a=l) 11 Ni2+ (a=l) | Ni is 0.51 and

Ni | Ni2* (at=l) 11 SCE is 0.49 V. Given = 0.24V.         (OS Marl

  1. Select the correct answer:

i)        The electrolyte used in Li-Mn02 battery is

A) 30% H2S04 .             B) 6M KOH

C) Li-halide and organic solvents D) NH4CI + ZnCh

ii)      Hot KOH solution should be used in H2O2 fuel cell

A) to increase conductivity B) to enhance the absorption of hydrogen on ano

C) for better reduction of O2    D) to avoid dilution of KOH.

m

iii)    In some batteries, graphite is used as an additive, because

A) it reduces the total weight   B) it absorbs the moisture

C) it improves the conductivity D) to increase the surface area of the electrode.

iv)    Lithium metal is used as anjadic material in Lithiuirl batteries because

Irons B) its reduction potential is very high

D)    it readily reacts with water.       (04 Mai

😕 Explain the construction, reactions and applications

 

(06 Mai

•istics of a battery:

i)  Capacity         ii) Cycle life.    (05 Mai

d. How is a fuel cell, in which chemical energy is converted into electrical energy, it advantageous over the conventional batteries? Justify – “fuel air is only an ene conversion device and not an energy storage device”.                                                                                                                                               (05 Ma

  1. Select the correct answer:

i)        Appropriate corrosion control for a buried pipeline is

A) Painting B) Cathodic protection C) Cathodic coating D) Metallic coating

ii)      Cathodic coating is

A) coating of tin on iron                                              B) coating of zinc on iron

C) conversion of whole specimen into cathode . D) immersion into hot ZnCh soln.

iii)    A bolt and a nut made of the same metal is preferred in practice to avoid

A) stress corrosion                                                      B) differential aeration corrosion

C)

    differential metal corrosion   D) caustic embrittlement.

iv)    The reaction at an anode during corrosion is

A)                                                                     Oxidation                          B) Reduction       C) Redox D) Conversion. (04 M:

  1. Define metallic corrosion. Discuss the following factors which influence ihc rat corrosion: i) Nature of corrosion products ii) Hydrogen over-voltage                                                                  (05 M
  2. What is anodizing? Explain the anodizing of aluminium. *                                                   (06 M
  3. Write a note on phosphating.                                                                                                (05 M
    1. Select the correct answer:

 

i)        ‘Pickling’ is

A) alkali cleaning B) acid cleaning C) organic solvent cleaning D) water cleaning

ii)      As temperature increases the electro-deposition

A) decreases                 B) increases

C) no effect                 D) first decreases and then increases

iii)    The experimentally determined discharge potential of an electrode is 2.58V and its theoretical discharge potential-is 1,53V; then over-voltage is

A) 3.345 V      B)-1.05 V C) 4.11 V D) 1.05 V

iv)    As over-voltage increases, electroplating

A) decreases   B) increases C) no change D) increases and decreases.

(04 Marks)

  1. Explain the significance of the following electroplating:

i) Polarization ii) Over-voltage.                        (08 Marks)

  1. Differentiate between electroplating and electroless plating.   (04 Marks)
  2. Explain the surface propagation and electroplating of chromium on a steel material.

___                                                      (04 Marks)

  1. Select the correct answer:

i)        The molecular ordering in nematic phase is

A)   No positional order and orientational order

B)   Perfect positional and orientational order

C)   No positional but orientational order

D)  Total loss in molecular ordering.

ii)      The layered structure is found in    phase.

A) nematic    B) discotic   C) meso        D) smectic

iii)    In potentiometric acid-base titration, the indicator elcctrode is

A) calomel    B) Ag-AgCl C) Glass-electrode D) platinum

iv)    Mathematical expression of Beer-Lambert law is

A)A — ~ log T = C/          B) A = log T = C/

C) log (I0 / It) = eCl       D) log (It /10) = eCl       (04 Marks)

  1. What are the liquid crystals? Discuss the classification, with examples.                                                 (07 Marks)
  2. Explain the liquid crystalline behaviour in PAA homologous series.   (04 Marks)
  3. Explain the theory behind the conductometric titration. Draw and explain the conductometric titration curve for the following titrations:

i) A strong acid and a strong base ii) A strong acid and a weak base.                                          (05 Marks)

  1. Select the correct answer:

i)        A polymer of high,optical clarity used in preparation of lenses is

A) Teflon    B) Phenol-formaldehyde C) Neoprene D) PMMA

 

7 a. ii) The glass transition temperature (Tj) depends on

A) type of monomer used       B) type of polymerization

C)                                                                                                                                            chemical resistance D) molecular weight

iii)      Monomer used in Teflon is

A) fluorine    B) bisphenol C) tetrafluoroethylene D) epichlorohydrin

iv)      The molecular weight of addition polymer is integral multiple of the molecular weight of monomer used because

A)                                                                                                                                         it is a linear polymer   B) no solvent in added

C)                                                                                                                                        it involves a catalyst  D) no eliminatioif of byproducts (04 Marks)

 

 

 

  1. What is polymerization? Explain the solution polymerization.
  2. Justify the following :

i)        Crystalline polymers possess higher strength than amorphous polymers.

ii)       Thermal control is rather difficult in bulk polymerization.

 

 

 

  1. What are resins? Give the synthesis, properties and uses of phenol-formaldehyde. (06 Marks)

 

(ArgentSmetric), the end point is brick-red, due to

B)        AgN03           C) AgCl D) Ag2Cr04

iii)                                                                                                                                                                                                                                                                                                                              Complexing agent/for spectrophotometric analysis of nitrate is              _

A) SPADNS B) Ammonia C) Phenol sulphonic acid D) Phenol disulphonic acid

iv)      The method removing temporary hardness is A) soda process B) boiling C) distillation

 

 Define alkalinity. If ‘P’ represents the phenolphthalein alkalinity and ‘M’ represents the methyl orange alkalinity, for a given sample of water, how do you predict the types of alkalinity, when (i) P = M (ii) P = 14 M (iii) P > Zi M (iv) P < Vi M ? (05 Marks)

  1. A river courses first through a terrain rich in limestone and through a terrain rich in gypsum. Identify the type of hardness it accumulates in its path. Explain the need for maintaining a constant pH and the colour changes that occur, when the hardness of this water is being determined by titration against EDTA, using Eriochrome black-T as the indicator. (05 Marks)
  2. Give an account of the following:

i)                        COD is higher than BOD

ii)                      HgS04 and Ag2S04 are to be added during COD analysis.

iii)      Chlorine is a powerful disinfectant only at lower pH values.

 

Calculate the gross calorific of a sample of coke from the following data:

Mass of coRe: 0.73×10′3kg Water equivalent of the calorimeter: 0.328 kg

Mass of water: 1.25 kg                          Specific heat of water: 4.187 kJ kg^K’1

Rise in temperature: 1.9 K.                                                                                                       (04 Marks)

Select the correct answer:

i)       Glass electrode can not be used in the presence of fluoride ions because A) alkaline error         B) loss its activity

C) glass membrane dissolves                                D) leads to asymmetric potential.

ii)     The value of EMF is ..  , if AG = -212.3 kJ/mol, T = 298 K and

Faraday constant = 9.65 kJ/V/mol.

C) 2.2 V                          D) 22.0 V

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