VTU Question Papers Engineering Chemistry May June 2010

VTU Question Papers Engineering Chemistry

2nd Sem B.E. Degree Examination, May/June 2010

 

Any FIVE full questions, choosing at least two from each part.

ML.,er all objective type questions only on OMR sheet page 5 of the Answer Booklet. ^Mwer to objective type questions on sheets other than OMR will not be valued.

PART-A

In Fischer-Trdpsch process, petrol is synthesized using A) Producer gas B) Water gas C) Coal gas D) Natural gas Lead tetra ethyl is added to gasoline to

A) Increase the octane number                                            B) Minimize knocking

C) Increase the efficiency of IC engine D) All of these.

A reference mixture used to find the octane number of gasoline is A) n-heptane and n-octane       _ B) n-heptane and isooctane

C) n-heptane and isobutene                                                   D) n-heptane and n-cetane

J Gasohol is a blend of gasoline with

A) Methanol                                B) Ethanol                           C) Propanol D) Butanol (04 Marks)

ne gross calorific value and net calorific value. Calculate GCV and NCV from the Owing data:

| of the fuel sample used for combustion = 0.85 x 10’3 kg

i                                                                                                                                                                        of water in the copper calorimeter = 2.35 kg |r .equivalent of calorimeter = 0.45 kg ific heat of water = 4.187 kJ/kg/K §a#e in temperature of water = 3.2°C           —

fat heat of condensation of steam = 2457 kJ/kg

ntage of hydrogen in the fuel sample = 2.5.                                                                                                          (06 Marks)

t is reformation? How reformation enhances octane rating? Illustrate with examples.

(05 Marks)

at is photo-voltaic cell? Explain the construction and working of PV cell. (05 Marks)

as,”

The reference electrode used in the measurement of standard reduction potential is A) Saturated.calomel electrode                                                                                                       B) Ag/AgCl electrode

C) Glass electrode                                                                  D) Standard hydrogen electrode

The electrode with -ve sign for its SRP acts as

A) Anode wiih respect io SHE                                              B) Cathode with respect to SHE

C) Acts as both                                                                         D) None of these

Potentiometer used for measurement of emf is calibrated using A) Ni-Cd ccll    _              B) Li-MnCh cell

C) Daniell cell                                                                           D) Weston standard Cd-cell

The emf of a concentration cell with 0.05 M and 0.025 M AgNOj solutions is A) 0.178 V       *B) 0.0295 V        C) 0.0178 V D) 0.125 V (04 Marks)

in the origin of single electrode potential and derive Nemst equation.                                                       (07 Marks)

  1. A galvanic cell is constructed by coupling Ag and Cd electrodes dipped in 0.5 M Ag’N
  2. and 0.25 M CdS04 respectively at 25°C. Write the cell scheme, cel! reaction, and caicul;
  3. emf of the cell. Given that SRPs of Ag and Cd are +0.80 V and -0.40 V respectively.

(04 Marl

  1. Give the principle involved in the determination of pH using glass electrode and explain method of determining pM using glass electrode.                                                                                                                                                                             (05 Marl

i)                 Which of the following is not a rechargeable battery?

A) Ni – Cd                                        B) Zn – MnC>2                            C) Li – MnC>2 D) Zn – air

ii)               Li – MnO? has higher emf than Zn – MnOi battery becauseA) Li is more electro +ve then Zn                                              B) SRP of Li is less then Zn

C) Li undergoes oxidation readily                                            D) All of these.

iii)             In H2 – O2 fuel cell the electrolyte KOH is kept in warm condition to ■

A)     Increase the efficiency    B) Increase the conductivity

C)        Maintain the electrolyte concentration D) Increase the emf

iv)             The fuel cell involving solid electrolyte is

A)         Molten carbonate B) Solid oxide

C)         Polymer electrolyte                                                                D) None               (04 Marl

Explain the following battery characteristics:

i)                                                                                                                                                                                                                                                                                                       Energy efficiency – ii) Cyele life—                                                                                                                                                                            (04 Marks]

Why secondary batteries are considered as storage batteries? Explain the construction working of Nickel-metal hydride battery. Give the reactions involved during discharge recharge modes.                                                                                     (06 Marl

How does a fuel cell differ from a battery? Explain the construction and working oj methanol-oxygen fuel cell with H2SO4 as electrolyte. Indicate the advantage of H2SO4

electrolyte over alkali electrolyte.

i)                 Pitting corrosion can be explained on the basis of A) Differential aeration                                                           B) Size of anode and cathode C) Localized corrosion D) All

ii)               In anodized aluminum, the corrosion protection is due to A) Passive oxide coating B) Phosphate coating C) Chromate coating                                                           D) None

iii)            Polarisation of anode results in

A)      Increase in the rate of corrosion

B)      Decrease in the rate of corrosion

C)      Increase in the rate of cathodic reaction                                           »

D)      Increase in the rate of anodic reaction.

iv)            Anodic protection can be applied to

A)      All the metals

B)      Metals which undergo active-passive transition

C)      More electro +ve metals

D)       Less electro+ve metals.                                                                                        (04 Marks]] Explain rusting of iron based on elcctro chemical phenomenon. (05 Marks] What is cathodic protection? Explain sacrificial anode and impressed current techniques.

,                                     . .                       (05 Marks)]

What ar<2 corrosion inhibitors? Explain corrosion inhibition % cathodic inhibitors. Give tb< reactions involved.                                                                                                                    (06 Marks)i

PART -B

In the process ol’electroplating there is

A) Electrolysis                                                B) Discharge of metal ions at cathode

C) Redox reaction                                          D) All

The practical decomposition is greater than the theoretical decomposition potential becausc of

A) Ionisation                                                      B) Dissociation

C) Polarisation of electrodes D) None

When an electrolytic mixture containing Zn”^, Cd*~\ Cu+t and Ag+ is electrolysed, the ion which is going to be discharged first is A)Zn^      B)Cu++ Q-Cd~ D) Ag+

The function of the complex ing agent in the electrolytic bath is to

A)         Increase the conductivity

B)        Maintain metal ion concentration at an optimum level

C)        Increase in the metal ion concentration

D)                             None.                                                                                                                                                                (04 Marks) xplain the effect of the following on the nature of electro deposit:

• Current density ii) pH                                        iii) Throwing power. «.                                                             (06 Marks)

plain The process of electroplating of chromium for engineering applications. Indicate the jasons for not employing chromium as anode.                                                                                                                                                             (05 Marks)

at is electroless plating? Explain electroless plating of nickel.                                                                             (05 Marks)

Para Azoxy Anisole is an example for A) Cholestric               B) Smectic

C) Chiral nematic                                         D) Nematic

In potentiometer calomel electrode is used in combination with A) Glass electrode                 B) Ag/AgCl electrode                                                                              «_

C) Pt-electrode                                                D) Quinhydrone electrode

Liquid crystals arc

A) Isotropic                                                       B) Optically anisotropic

C) Optically isotropic                                    D) Aii

In flame photometry the emitted radiation lies in A) IR range              B) UV range

C) Visible range                                               D) All the three,

t are thermotropic and lyotropic liquid crystals? Give examples, efine specific conductance. Explain conductometric estimation of HC1 using standard JutionofNaOH.                                                                                                      (05 Marks)

tate and explain Lambert’s law and Beer’s law. Explain in brief the estimation of copper by Slorimetric method.           (07 Marks)

 

 

Natural rubber is the polymerized form of A) Chloroprene B) Isoprene Condensation polymerization is

A)      Homo polymerisation

C)          Copolymerisation with elimination Glass transition temperature of polymer is

A)     First order transition

C)      Inner transition

C)   Propene

B)   Chain polymerisation

D)    Copolymerisation without elimination

B)      Second order transition

D)    Poly order transition.


  1. iv) In suspension polymerization the monomer droplets are stabilized by using

A) Emulsifying agent                                               B) Coagulants

C)   Anticoagulants                                      D) Deemulsifying agent

  1. Explain free radical mechanism of addition polymerization talcing ethane as monomer.

(04 Mi

  1. Give the polymerization reaction involved in the synthesis of the following polymers:
  2. i)            Plexiglass ii) Polyurethane                                    iii) Epoxy resin iv) Butyl rubber (08 Mai
  3. d- What are conducting polymers? Explain conduction mechanism in doped poli acetylene!

. . ‘                                                                 (04 Mai

8 a. i) Permanent hardness of water is due to                                                                                                   ;

A) Ca(HC03)2 B) CaC03                                           C) CaS04 D) MgC03 ?

ii)               Indicator used in the determination of chloride using AgN03 is

A) K3[Fe(CN)6] B) K4[Fe(CN)6] C) K2Cr04 D) K2Cr207

iii)            Excessive fluoride in water leads to A) Dental carries B) Silicosis                                                                                     C) Fluorosis D)A11

iv)            The method adopted to convert saline water into potable water is A) Demineralisation                           „ B) Ion exchange process

C)              Pemiutit process D) Electrodialysis                                                                                       (04 Nil

  1. Explain Winkler’s method of determining dissolved oxygen. Give the reactions involve]

(05 Mi

c– What is desalination? Explain desalination of water by reverse osmosis.                                       (06

d- While analyzing a water sample to determine alkalinity, 100 ml of sample water coi

12.4 ml of ^H2S04 till phenolphthalein end-point. On further titration of the r<

mixture using methyl orange indicator, the total consumption of — H2SC>4 was 1 Determine the type and extent of alkalinity.                                                                                                                                                                 (05


 

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