VTU Exam papers Engineering Chemistry December 2011

VTU Exam papers Engineering Chemistry

First/Second Semester B.E. Degree Examination, December 2011

 

Time: 3 hrs.

s: 100

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

2- Answer all objective type questions only on OMR sheet page 5 of the answer booklet. 3. Answer to objective type questions on sheets other than OMR will not be valued,

PART-A

1         a. Choose your answers for the following :                                                                (04 Marks)

B) Hydrogen electrode

C) Ag-Agcl electrode                                 .D) Standard hydrogen electrode

i   The reference electrode used in measurement of standard reduction potential is A) Standard calomel electrode

ii  When the concentration of chloride ions in Ag-Agcl electrode increases, the potential of the electrode

A) Increases                                                 B) Decreases

C) Does not change                                     D) None of these

iii)       Nemsts equation is based on

A)    Thermodynamic principle

B)   An equation for redox potential

C)      Increase in the free energy of the system

D)   None of the above

iv)       In a Galvanic cell oxidation takes place at

A) Electrolyte B) Cathode                         C) Anode                   D) .Salt bridge

  1. What are concentration cells? Derive an expression for the EMF of a concentration cell.

(05 Marks)

c– Define standard electrode potential. Explain the origin of electrode potential. (06 Marks) d. An electro chemical cell is formed from nickel and lead electrodes having 0.01m NiSC>4 and 0.5m PbSCU Electrolytes. The standard electrode potentials of Ni and Pb electrodes are – 0.24V and – 0.13V respectively. Write the cell scheme, cell reaction and calculate EMF of the cell at 298 K.    (OS Marks)

2          a. Choose your answers for the following :                                                                (04 Marks)

i)            Cycle life is applicable only to

A) Primary batteries                                    B) Secondary batteries

C) Reserve batteries                                    D) All the above

ii)         The electrolyte used in zn – air battery is

A) aqH2S04                                                    B) Conc.KC/

C) Aq.KOH                                                   D) Aq.Hc/

iii)       EMF of a battery depends on

A) Standard electrode potential                B) Temperature

C) Reaction quotient                                   D) All the above

iv)       The fuel cells are more superior than the batteries as

A) They are light in weight                        B) They are eco friendly

C) They produce current at low cost D) All the above

 

  1. Discuss construction and working of load-acid storage battery.                    (06 Marta)
  2. Explain construction and working of Ni-MH battery.                                       (04 Marks)
  3. What are fuel cells? Describe die construction and working of CH3OH – 02 fuel cell.

(06 Marks)

  1. Choose your answers for the following:                                                             (04 Marks)

i)            At high hydrogen over voltage, the rate of corrosion

A) Increases                                                 B) Decreases

C) Increases initially and then decreases D) Remains un changed

ii)          Metal iron is coated with zinc metal to prevent corrosion. The process is A) Anodic coating                                                          B) Cathodic coating

C) Inorganic coating                                   D) Painting

iii)       In corrosion, the gas which is produced in acidic medium is A) Hydrogen           B) Oxygen

C) Nitrogen                                                  D) Carbon dioxide

iv)        The type of corrosion occuring in wire fence is

Galvanic corrosion   B) Inter – granular corrosion

C)  Differential aeration corrosion  D) Water – line corrosion

  1. Discuss :

i)             Stress corrosion

ii)          Water line corrosion,                                                                                   (06 Marks)

  1. Explain the influence of following factors on the rate of corrosion :

i)   Nature of corrosion product ; ii) Anodic and cathodic area.                  (04 Marks)

  1. Describe the following process: i) Galvanising ; ii) Tinning.                          (06 Marks)
  2. Choose your answers for the following :                                                           (04 Marks)

i)            In electroplating, the article to be plated is subjected to pickling. This is to

A) Remove grease    B) Increase rate of plating C) Remove oxide scale D) Get a bright deposit

ii)          The decomposition potential is equal to

A) BackEMF                                                B) Cell voltage

C) Current density                                      D) None of the above

iii)       Brightners are added to plating bath in order to

A)    To get uniform deposit

B)   Make grain size of the deposit smaller than X of light

C)   To get thick deposit

D)   Remove colour

iv)        Which of the following is essential in electroless plating

A)       Oxidising agent     B) Reducing agent

C)      Anode         D) Electrical energy

  1. What is meant by metal finishing? Explain the process of electroplating of gold. (06 Marks)
  2. Discuss the influence of the following in electroplating bath solution. <2>      (04 Marks)
  3. What is electroless plating? Explain electroless plating of nickel, with relavent reactions.

Q)                                     o^X                                                                                                                                (06 Marks)

PART-B

5 a. Choose your answers for the following:                                                                   (04 Marks)

i)             The process of breaking down hydrocarbons of higher molecular weight into lighter hydrocarbons is known as

A) Refining                                                   B) Reforming

C) Isomerization                                          D) Cracking

ii)          The octane number of a fuel is a measure of

A)    Its ability to resist anti knocking

B)   Inability to offer resistance for knocking

C)   Its ability to resist knocking

D)   None of the above.

iii)        The addition of TEL to gasoline is

A)   Decreases the octane number

B)    Increases the octane number

C)   Decreases the cetane number

D)    Increases the cetane number

iv)        Photovoltaic cell consists of

A) p-n junction                                             B) n- type junction

C) p – type junction                                      D) None of the above

  1. What is reforming of petroleum? Give any four reactions involved in reforming. (06 Marks)
  2. Discuss the following: i) Power alcohol ; ii)Biodiesl.                                       (06 Marks)
  3. On burning 0.85 x 10′3 kg of a solid fuel in a bomb calorimeter, the temperature of 2.1 kg water is raised from 24°C to 27.6°C. The water equivalent of calorimeter and latent heat of steam are 1.1 kg and 2454 U/kg respectively. Specific heat of water is 4.187 kJ/kg. If the fuel contains 2% hydrogen, calculate its gross and net calorific values.                                     (04 Marks)
  4. Choose your answers for the following:                                                             (04 Marks)

i)            Flame photometer is based on

A) Atomic absorption                                B) Molecular absorption

C) Atomic emission                                    D) All the above

ii)          Condensed phase rule for a two component system is

A) P+F=C+3                                           B)P + F = C- 2

C)P + C = F + 1                                         D)P + F = C + 1

iii)       At eutectic point the composition of lead and silver h

A) Lowest melting point

B) Highest melting point

C) Lowest boiling point

D) Highest boiling point

iv)        The filter used in copper colorimetry is

A) 420 nm                                                    B) 520 nm

C) 620 nm                                                    D) 320 nm

  1. State phase rule. Give phase diagram of water system and explain application of phase rule to water system.                                                                                                           (06 Marks)
  2. Explain the application of phase-rule to lead silver system.                           (06 Marks)
  3. Give the components of the instruments required for potentiometry. Explain an application ofpotentiometry.                                                                                                     (04 Marks)

i)

Keviarisa

A) Polyurethane B) Polycarbonate C) Polystyrene D) Polyamide

ii)         Which one is a conducting polymer?

A) Aniline                 B) Pyrrole

iii)       Very high molecular weight polymers will have

A) LowTg                  B) HighTg                 C) Moderate Tg D)NoTg

iv)       The polymer widely used in making inner tubes of tyre is A) Neoprene rubber                                                           B) Butyl rubber C) Styru-butadiene rubber D) Natural rubber

  1. What are polymers? Discuss the free radical mechanism of polymerization of ethylene.

– (05 Marks)

  1. Give the synthesis and an application of i) Silicone rubber ; ii) Teflon.       (06 Marks)
  2. What are die deficiencies of natural rubber? Explain vulcanization of rubber. (05 Marks)

8                        a. Choose your answers for the following:                                                        (04 Marks)

i)            Chloride content of water sample is detennined by

A) Colorimetric method .                           B) Argentometric method

C)   SPADNS method     D) Gravimetric method

ii)         As the temperature increases, the amount of dissolved oxygen of water sample A) Increases                                                      B) Decreases

C)    Has no effect    D) None of the above

iii)       Reverse osmosis is a method of getting pure water from

A) Sewage water

B) Industrial waste water

C) Seawater

D) River water

iv)       Estimation of total hardness of water using EDTA titrant involves A) Neutralisation reaction                                                        B) Redox reaction

C)                                                                                                                                     Precipitation reaction         D) Complexometric reaction

  1. How is alkalinity of water caused? Explain the method of determination of alkalinity.

(06 Marks)

■ Describe electrodialysis method of desalination of water.                               (06 Marks)

• 25 CC of waste water was mixed with 25 CC of K2Cr207, acidified and refluxed. The unreacted K2 Cr2C>7 required 8.2 CC of 0.2N FAS. In a blank titration 25 CC of K.2Cr207 acidified required 16.4 CC of same FAS. Calculate COD of waste water.                                                (04 Marks)

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