MANIPAL UNIVERSITY

I SEMESTER B.E. END SEMESTER EXAMINATION

SUBJECT: ENGG. CHEMISTRY (CHM 101)

Time: 3Hours Date: 11-12-2009 Max .Marks :50

NOTE : Answer any FIVE full questions.

1.A Account for the following:

i)Salt bridge of KCl cannot be used for a cell made up of Ag and Pb half- cells. ii)A dry cell becomes dead after a long time, even if it has not been used.

1.B What are ion selective electrodes? Give the construction of glass electrode. Derive an expression for electrode potential of glass electrode and explain the experimental method for the determination of pH using glass electrode.

1.C i) Explain the mechanism of galvanic corrosion. How can it be controlled? ii)How is vulcanization of rubber carried out? How does it improve the property

of natural rubber. [2+ 4+4 = 10M] 2.A Write a note on LPG.

2B. i) Explain free radical addition polymerization mechanism of styrene. ii)Why can not Teflon be moulded by conventional methods iii) Thermal control is difficult in bulk polymerization.-Justify.

2C. i)The emf of an electrochemical cell consists of iron electrode dipped in 0.1M FeSO4 and silver electrode in AgNO3(x) is 1.1926V. Write the cell reaction and

calculate the strength of AgNO3. Given that the standard electrode potentials of iron and silver electrodes are –0.44V and +0.80V respectively.

ii) Discuss the following factors influencing the rate of corrosion.

a) Temperature b) Nature of the electrolyte. [2+ 4+4 = 10M]

3A. i) Why nylon 6,6 exhibits higher Tg than that of polyethylene? ii) Why a polymer membrane is used at the cathode in methanol-oxygen fuel cell.

3B. i) Discuss the effect of structure of polymer on the following properties.

a) crystallinity b) plastic deformation. ii)Explain the experimental determination of decomposition potential of an

electrolyte. 3C. i) Write two differences between the following:

a) Addition and condensation polymer.

b) E.m.f series and galvanic series. ii) Write the main reactions that occur during reforming of petroleum.

[ 2+ 4 +4 =10M]

4A. i)What is the principle of Boys’ gas calorimeter used in the determination of calorific value of a gaseous fuel.

ii) The gross calorific value of a sample of bituminuous coal is 30,000 kJkg-1.In an experiment, 0.8 g of this coal was burnt under 1.2 kg of water rose by

3.92oC.Calculate the water equivalent of the calorimeter. Specific heat of water=4.2kJkg-1/ oC.

4B i)With a neat diagram explain the manufacture of water gas. Mention any two of

its applications. ii) Explain with examples how cathodic inhibitors provide protection against

corrosion. 4C. i) What is meant by critical micelle concentration (CMC) of a surfactant? Discuss

the role of surfactants in an emulsion polymerization technique.

ii) Give reasons for the following: a) Presence of ash and volatile matter is undesirable in coal.

b) Absolute electrode potentials cannot be measured. [2+4+4 = 10M]

5A. Justify the following statements.

i) Lead acid batteries should not be overcharged. ii) Concentration polarization can be eliminated.

5B. i) Give the construction and working of Nickel- Cadmium cell during discharging process. What are its advantages? ii) Explain the construction, working and applications of a Calomel electrode.

5C. i)The emf of the cell: Cd(s)/ CdCl 2(aq) / AgCl(aq)/Ag is 0.7653V at 298K and 0.6915V at 273K. Calculate ∆G, ∆H, and ∆S for the reaction at 298K.

ii) Explain the main objectives and uses of Chromium plating. Why Chromium plating has nickel undercoat?

[2 +4+4 =10M]

6A. Describe the Pogendorff’s method of determination of e.m.f of a cell. 6B. i) The emf of the following concentration cell is 0.101V. Find the concentration

of anolyte. Ag/Ag+(x) // Ag+(0.5) / Ag. ii)Discuss the preparation and any two properties of the following polymers. a) Epoxy resin b) Silicone rubber. c ) Nylon 6,6

6C. i) Write a note on reclaimed rubber. ii)1.55 g of the coal sample in a quantitative analysis gave 0.1675 g of BaSO4.

Calulate the % of S in the coal sample. iii)0.125 g of coal on combustion gave 0.3960 g of CO2 and 0.0195 g of H2O. Calculate the % of C and H in the coal sample.

[ 2 + 4 + 4 =10M]

MANIPAL UNIVERSITY I SEMESTER B.E. END SEMESTER EXAMINATION

SUBJECT: ENGG. CHEMISTRY (CHM 101) ( Make up Examination)

Time : 3 hrs Date: 30-12-2009 Max. Marks: 50

NOTE : Answer any FIVE full question

1A i)What is unleaded petrol? What are its advantages?

ii) Solutions of high conductance are used in electroplating: Justify 1B. i) Derive Nernst equation for single electrode potential.

ii) Explain the construction and working of a glass electrode. Mention any two of its

advantages and disadvantages. 1C. With a neat diagram explain an experimental method to determine the calorific value

of a solid fuel using Bomb calorimeter. ( 2+ 4+4 =10M) 2A Give reasons for the following.

i) PVC is soft and flexible; where as Bakelite is hard and brittle. ii) Virgin rubber is useless as pure gold.

2B i)What do you understand by vulcanization of rubber? What are its advantages and disadvantages? Give the structural unit of vulcanized rubber.

ii) Give the preparation and any two applications of Epoxy resin

2C. i) A coal has the following composition by weight : C = 90%; O = 3.0%; S = 0.5%; N = 0.5% and ash = 2.5%. Net calorific value of the coal was found to be 8,490.5 kcal/kg.

Calculate the percentage of hydrogen and higher calorific value of coal. (ii) Explain pitting corrosion. ( 2+ 4+4 =10M)

3A. Give reasons for the following: i) Galvanized articles should not be used for storage of food products.

ii) Wire mesh corrodes at the joints. 3B. i) Give an account of passivity of metals.

ii) Explain cathodic protection of metals.

3C. i)Explain suspension polymerization and give any two of its advantages and disadvantages.

ii) What are the differences between natural rubber and gutta percha. ( 2+ 4+4 =10M)

4A i) Write any two differences between electroplating and electroless plating.

4B. i) Write an informative note on effect of structure on crystalllinity and chemical resistance of polymer.

ii) Give the construction of lead storage cell and write the reactions taking place during its discharge.

4C. Give an account of electroless plating of copper.

( 2+ 4+4 =10M)

5A Give reasons for the following:

i) Why is calorific value of water gas higher than that of producer gas? ii) Concentration of KOH remains invariant in Nickel Cadmium cell.

5B i) With suitable examples explain the function of cathodic inhibitors in corrosion control. ii) Explain the mechanism of free radical polymerization of ethylene. 5C i) What are concentration cells? Derive an expression for e.m.f of a concentration cell.

ii) Calculate the emf of the concentration cell at 25oC Ag(s)/AgNO3 (0.018 M) / AgNO3 (1.20 M) /Ag(s).

If water is added to the more dilute solution what happens to the emf of the cell ( 2+ 4+4 =10M)

6A Make a clear distinction between the following ( Any two points) i) Polythene and silicone rubber

ii) Galvanic cell and fuel cell. 6B i) Give a brief account of antiknocking agents ii) Distinguish between Galvanizing and Tinning

6C i) With a neat diagram explain the production of producer gas. Mention any two of its applications

ii) Explain the construction and working H2 – O2 fuel cell. Mention any two of its advantages and disadvantages of the same.

( 2+ 4+4 =10M)

MANIPAL UNIVERSITY

CHEMISTRY DEPARTMENT –M.I.T. MANIPAL.

I SEMESTER B.E. END SEMESTER EXAMINATION

SUBJECT: ENGG. CHEMISTRY (CHM 101)

Time: 3 hrs Date: 20-11- 2009 Max. Marks: 50

NOTE: Answer any FIVE full questions.

1.A. i) Explain the construction and working of methanol-oxygen fuel cell.

ii) Define metallic corrosion. Explain the electrochemical theory of corrosion taking iron as an example. 1.B. i) Discuss the method of determining the potential of a single electrode using

hydrogen electrode. ii) Write any four advantages of electroless plating over electroplating.

1.C. Give reasons: i) Teflon is an addition polymer but it behaves like thermosetting polymer. ii) Iron in contact with copper undergoes corrosion faster than the iron in contact

with tin. [4 + 4 + 2 =10M ]

2.A. i) Describe the use of inhibitors in corrosion control. ii) Discuss the mechanism of free radical addition polymerisation with an example. 2.B. i) Explain the fluidised catalytic cracking process. What are its merits?

ii) Calculate Eo Zn 2+

/ Zn , if the emf of Zn /Zn 2+ (1M) // Ni 2+ (1M) /Ni is 0.51V and Ni/Ni 2+ (1M) // SCE is 0.49 V. Given E SCE = 0.24 V.

2.C. Give reasons: i) Water formed in the hydrogen-oxygen fuel cell should be continuously removed. ii) A secondary cell can operate both as an electrochemical cell and electrolytic cell.

[4 + 4 + 2 =10M] 3.A. i) Describe the construction and working of Dry cell with reactions.

ii) Calculate the gross and net calorific value of a gaseous fuel at STP from the following data:

Volume of gas burnt = 0.0188 m3 at STP

Mass of water passing through the calorimeter = 4.5 Kg Rise in temperature = 18.5 K

Amount of water collected = 7.5 cm3 Latent heat of steam = 587kcal/kg

3.B. i)Derive an equation which relates electrode potential and concentration of electrolyte

in a half cell. ii) Give the method of synthesis and any two properties of phenol- formaldehyde resin.

3.C. How do the following factors affect the rate of corrosion? i) nature of the corrosion product (ii) relative area of anode and cathode.

[4 + 4 + 2 =10M]

4.A. i) Describe the manufacture of producer gas and mention its two important uses. ii) Explain the electroplating of decorative chromium. 4.B. Discuss the followings

i) Caustic embrittlement. (ii) Corrosion control by cathodic protection. 4. C. Give reason:

i) Salt bridge or porous plate is not required in lead acid batteries. ii) Calomel electrode should not be used above 50oC. [4 + 4 + 2=10M]

5.A. i) What are ion selective electrodes? Derive an expression for electrode potential of a glass electrode.

ii)What is a standard cell? Explain the construction and working of Weston standard cadmium cell. 5.B. i) Write an explanatory note on the compounding of rubber.

ii) Define knocking. With an example explain the importance of adding antiknocking reagent to petrol.

5.C. i) 28g of ethene was polymerised by radical polymerisation and degree of polymerisation was found to be 1000. Calculate the number of molecules of polythene produced.

ii) How much rust (Fe2O3. 3H2O) is formed when 100kg iron have completely rusted away. (At. Weight: Fe =56, O =16, H =1)

[4 + 4 + 2 =10M] 6.A. Distinguish (any two points) between each of the following pairs of terms. i) Galvanic corrosion and waterline corrosion. (ii) number average molecular weight

and weight average molecular weight (iii) Concentration polarisation and activation polarisation. (iv) Solution polymerisation and emulsion polymerisation technique.

6.B. i) EMF of the Weston cadmium cell is 1.0183 V at 293 K and 1.0181 at 298K. Calculate change in free energy, change in enthalpy and change in entropy at 298K.

ii) Explain the effect of structure of polymer on chemical resistance and tensile

strength. 6.C. Give an account of thermal reforming of petroleum.

( 4 + 4 + 2 =10M )

*********

MANIPAL UNIVERSITY

Department of Chemistry. MIT. Manipal

II SEMESTER B.E DEGREE EXAMINATION

ENGG CHEMISTRY (CHM 101)

Time : 3hr 15-05-2009 Max.Marks : 50

Note: Answer any FIVE full questions.

1.A i) Give reasons for the following:

a) The e.m.f of a galvanic cell is always positive and never greater than 2 Volts.

b) For a given reduction reaction, higher the concentration of electrolyte, lower

will be the reduction potential and vise versa.

1.B i)Represent a galvanic cell and write electrode reactions for the following

cell reaction: Zn (s) + 2AgCl ---- 2Ag + ZnCl2

ii) Write two differences between number average and weight average molecular

weight.

iii) In a sample of polystyrene, polymers of different degree of polymerization are

in the ratio of 2: 3: 4: 6. The degree of polymerization of the samples are 345,

570, 800 and 925 respectively. Calculate number average and weight average

molecular weight. (Given: atomic wt of C = 12 and H = 1)

1.C i) Compare the composition of producer gas and water gas. Which is the better

fuel and why?

ii) Explain in detail any two factors affecting the nature of electrodeposit .

[ 2 + 4 + 4 = 10M]

2.A i) Give reasons for the following:

a) Maintenance free batteries are preferred to lead storage cell.

b) A membrane must be placed adjacent to the cathode in a methanol- oxygen fuel

cell.

2.B i) For a electrochemical cell

Cd,CdCl2 5/2 H2O/AgCl(s),Ag the e.m.f at 0oC and 25

oC is 0.6915V and

0.6753V respectively. Calculate standard free energy, enthalpy and entropy

change.

ii)Explaining the passivating nature of metal & discuss anodic protection of

metals.

2.C i) With relevant structure, explain the variation in glass transition temperature in

polythene, polyvinyl chloride, polystyrene and ά methyl polystyrene.

[ 2 + 4 + 4 = 10M]

3.A i) Give reasons for the following:

a) Water fed to the boiler during steam generation must be deionized

b) Corrosion can not be controlled effectively, if inadequate amount of anodic

inhibitor is present in the corrosive environment.

3.B i) In a concentration cell, Ag electrodes are immersed in different concentrations

of AgNO3. Concentration of AgNO3 in the anodic compartment is 0.05M.

Calculate the strength of AgNO3 in the cathodic compartment.( Given: E.M.F of

the cell is 0.25V.) When would the e.m.f of this cell become zero?

ii) Differentiate between concentration and activation polarization. Discuss the

mechanism of activation polarization.

3.C i) By giving appropriate reasons, write any one application of nylon 6,6, Teflon,

SBR and epoxy resin.

ii) Write a note on compounding of rubber. [ 2 + 4 + 4 = 10M]

4.A i) Give reasons for the following :

a) TEL along with ethylene dibromide reduces the knocking tendency of gasoline

used in I.C engines.

b) Petroleum cracking and reforming increases the yield and the quality of

gasoline.

4.B i) With a suitable example, explain the differential aeration corrosion. How is it

different from galvanic corrosion?

ii) Give the principle of anode and cathode metal coating. Write two limitations of

cathode metal coating.

4.C i) Give the construction of Ni-Cad cell. Write the electrode reaction and cell

reaction of the same during discharge of the cell. Comment of the strength of

electrolyte at the end of the discharge process.

ii) A bomb calorimeter experiment using 0.8g of coal gave the gross calorific

value 3781.25 cal .g-1

, by showing an increase in temperature of 2.2oC. The

weight of water taken in the calorimeter was 1250g. Calculate the water

equivalent of the calorimeter. If the coal sample contains 5.2% of hydrogen,

Calculate the net calorific value. [ 2 + 4 + 4 = 10M]

5.A i) Give reasons for the following:

a) Electroplating of chromium is carried out using inert electrodes.

b) Silicone rubber cannot be vulcanized using sulphur.

5.B i) With relevant principle and required calculation steps explain ultimate analysis

of coal for the determination of % C & H.

ii) Compare and contrast suspension and emulsion polymerization.

5.C i) Why glass electrode is known as indicator electrode? Derive an expression for

glass electrode potential.

ii) Discuss in detail any two applications of fuel cell. [ 2 + 4 + 4 = 10 M]

6.A i) Give reasons for the following:

a) Hydrogen electrode can not be used when the electrolyte contains redox

reagents and impurities.

b) .Isotactic and syndiotactc polymers are hard but atactic polymers are soft.

6.B. i) Explain the principle of electroless plating. Why is it better than electroplating?

ii) Define a standard cell. Explain the determination of e.m. f . of a cell.

6.C i) How does electrochemical theory of corrosion explain the formation of yellow

and black rust.

ii) Write 4 differences between addition and condensation polymerization.

[ 2 + 4 + 4 = 10M]

MANIPAL UNIVERSITY

FIRST SEMESTER B.E. DEGREE EXAMINATIONS NOVEMBER 2008

SUBJECT: ENGINEERING CHEMISTRY (CHM 101)

Time:3hrs. Date:24-11-2008 Max. Marks: 50 Note: Answer any FIVE full questions. 1A. Explain the concept of free energy changes in electrochemical cells and derive expressions for free energy, enthalpy and entropy relating to the e.m.f of the cell. 1B i) Give the cell representation and electrode reactions of a Standard cell.

ii) Describe the construction and give the reactions during discharge of the Ni-Cd cell. Mention two important applications of the cell.

1C. Give reasons: i) Chromium anodes are not used in electroplating.

ii) Pin holes on tin coated iron are more prone to corrosion of iron than those on zinc coated iron

[4 + 4 + 2 =10M] 2A. Give an account of the following:

i) Differences between natural and synthetic rubber. (Any four) ii) Factors affecting the glass transition temperature of polymers.

2B. What are adhesives? Give the method of synthesis, properties and any two applications of Epoxy resin. 2C. The following data were obtained in a Boy’s gas calorimeter experiment. Volume of gas used = 0.1 m3 at STP Wt. of cooling water = 25 Kg Temp. of inlet water = 20oC Temp. of outlet water = 33oC Wt. of steam condensed = 0.025 Kg

Calculate HCV and LCV per m3 at STP. Take the heat liberated in condensing water vapour and cooling the condensate as 580 KCals / Kg

[ 4 + 4+ 2 = 10M] 3A. Describe the manufacture of water gas and mention its two important uses. 3B. Give an account of the following:

i) Effect of current density and temperature on electroplating. ii)Electroless plating of copper.

3C. A polymer of polypropylene is found to have the following composition. i) [ ] 400 20% CH CH2

CH3 ii) [ ] 500 30% CH2 CH

CH3 P.T.O

iii) [ ] 600 50% CH2 CH

CH3 Calculate the number average and weight average molecular masses of the polymer. (Atomic masses of C =12 & H =1). [ 4 + 4 + 2 = 10] 4A. Explain the following.

i) Caustic embrittlement. ii) Waterline corrosion. 4B. Discuss the following.

i) Effect of structure of polymer on crystallinity & chemical resistance. ii) Technique of emulsion polymerization.

4C. A sample of coal was analysed as follows. Exactly 2.5g was weighed into a silica crucible. After heating for 1 hr. at 110oC, the residue weighed 2.415g. The crucible next was covered with a vented lid & strongly heated for exactly seven minutes at 950 ± 20oC.The residue weighed 1.528g. The crucible was then heated without cover, until a constant weight was obtained. The last residue was found to weigh 0.245g. Calculate percentage of moisture, volatile matter, ash & fixed carbon in the sample.

[4 + 4 + 2 = 10] 5A . What are fuel cells? Explain the construction and working of H2–O2 fuel cell. Mention any two advantages of fuel cell. 5B. Give reasons for the following. I) Bakelite is hard and rigid while PVC is soft and flexible. ii) Natural rubber needs vulcanization. iii) Rusting of Iron is prevented if the article is connected by a wire to Mg. iv) Salt bridge is used in the construction of galvanic cell. 5C Calculate the e.m.f of a Cadmium-Copper cell in which Cadmium is in contact with 0.003M CdSO4 and Copper in contact with 0.03M CuSO4 solution. The standard e.m.f. of the cell is 0.86V at 298K. [ 4 + 4 + 2 = 10] 6A. Describe the various reforming reactions with one example in each case. 6B. Discuss the following. i) Prevention of corrosion by proper selection of material and designing. ii) Methods of cleaning the metal surface before electroplating. 6C. Give reasons for the following. i) Addition of amines, thiourea etc. to corrosive environment reduces corrosion of metals. ii) Tetraethyl lead mixed with ethylene dibromide is added to gasoline used in vehicles. [ 4 + 4 + 2 = 10]

MANIPAL INSTITUTE OF TECHNOLOGY MANIPAL UNIVERSITY

I SEMESTER B.E DEGREE MAKE UP EXAMINATION

JAN 2009

SUBJECT: ENGG. CHEMISTRY. (CHM 101/102) DATE: 01-01-2009

Time: 3 Hrs] [Max. Marks: 50 Note: Answer any FIVE full questions. 1. A Give reason for the following:

i) Electrode potential of calomel electrode varies inversely with the strength of KCl solution. ii) Potentiometer is preferred to voltmeter for the accurate measurement of e.m.f of the galvanic cell.

B i) Define and derive mathematical expression for Mn and Mw. ii) With an example distinguish between an elastomer and a fiber.

C i) Explain with a neat diagram fluidized catalytic cracking. What are its merits? ii) 0.945g of a solid fuel on complete combustion in excess of oxygen increased the temperature of water in a calorimeter from 13.25oC to 19.2oC. The mass of water in calorimeter was found to be 1458g. Water equivalent of calorimeter and the stirrer was 456g. Calculate the gross calorific value and net calorific value if the fuel contains 8% of hydrogen, ( Latent heat of condensation of steam is 586cal /g)

[ 2 + 4 + 4 = 10M]. 2. A Give reason for the following: i) Secondary reaction do not contribute towards e.m.f of dry / Leclanche cell. ii) Lead storage cell should neither be over charged nor kept in partially discharged condition. B i) Write an explanatory note on anodic and cathodic inhibitors which are used in

corrosion control ii) With a suitable example, explain the functions of salt bridge in a galvanic cell.

C. i) What is meant by electroless plating? Discuss the various methods applied for the activation of the surface in electroless plating. ii) Write the method of preparation and any two important uses of nylon 6,6 and SBR.

[ 2 + 4 + 4 = 10M] 3. A Give reason for the following: i) Rate of corrosion of metal is more in aerated acid solution. ii) Continuous current supply is needed for anodic protection of metals. B i) Explain the development of potential in a glass electrode and derive an

expression for glass electrode potential. ii) The potential of hydrogen gas electrode in a solution of acid of unknown strength is 0.34V at 298K as measured against SHE. Calculate the pH of the solution.

C i) Explain the mechanism of petroleum knocking. How can it be prevented?

ii) Explain suspension polymerization technique. In what aspects it is different from emulsion polymerization?

[ 2 + 4 + 4 = 10M] 4. A Give reason for the following:

i) Higher the volatile matter and ash content, lower will be the calorific value of a chemical fuel. ii) Steam and air are passed alternatively in the production of water gas.

B i) Give the schematic representation of Ni-Cad cell. Write the electrode reactions and cell reaction taking place during the discharge of the cell. ii) List any four important requirements of fuel cell. Write any two merits and two demerits of the same.

C i) With relevant equations explain caustic embrittlement. ii) Define glass transition temperature. With appropriate structure, explain the reason for observed variation in Tg values, in case of polyethylene, polyvinyl chloride and polystyrene.

[ 2 + 4 + 4 = 10M] 5.A Give reason for the following:

i) Separation of the ions from the mixture can be done with the knowledge of decomposition potential ii) Complexing agent is sometimes added to the electrolytic bath for a good elelctrodeposit.

B i) Justify: e.m.f of a galvanic cell is always positive. The e.m.f of a galvanic cell Cd/CdCl2 2.5 H2O // AgCl/Ag is 0.7653V at 25oC, and 0.6915V at 0oC. Calculate enthalpy change and entropy change for the reaction at 25oC. ii) Explain following properties of the polymer with reference to the structure: Plastic deformation and Chemical resistance

C. i) Explain ultimate analysis of coal for the determination of carbon and hydrogen. ii) 1.56g of coal was Kjeldalised and NH3 thus evolved was absorbed in 50ml 0.1 N sulphuric acid. After absorption the excess acid required 6.25ml of 0.1N NaOH for exact neutralization. 2.60g of coal on quantitative analysis gave 0.1755g of BaSO4. Calculate % Nitrogen and % sulphur in the coal sample.

[ 2 + 4 + 4 = 10M] 6.A Give reason for the following: i) E.m.f of a concentration cell decreases with time and eventually becomes zero. ii) Part of a nail inside the wood undergoes corrosion easily. B. i) Explain the effect of following factors on the rate of corrosion: Anode area to cathode area ratio and Temperature. ii) Define tacticity. Explain this with respect to the structure of polypropylene. C. i) Explain the origin of single electrode potential.

ii) Explain the galvanization process. Why should not the galvanized articles be used for storing food stuffs.

[ 2 + 4 + 4 = 10M]

MANIPAL INSTITUTE OF TECHNOLOGY

MANIPAL UNIVERSITY I SEMESTER B.E DEGREE EXAMINATION NOVEMBER 2008

SUBJECT: ENGG. CHEMISTRY.(CHM 101/102) Scheme of Valuation

Time: 3 Hrs] [Max. Marks: 50 Note: Answer any FIVE full questions 1. a) Give reason i) E = Eo – 0.0592 log [Cl-]----------½M Explanation----------- ½M

ii) Two reasons ------------------------1 M

b) i) Defination ------1M Derivation of Mn & Mw --- -2M ii) One major difference with an example---------------½M + -½M

c) i) Diagram-----½M Conditions like Temp, Pressure & Catalyst----1M Process-----1M Merits ( any two)-------------- ½M ii) Calculation of G.C.V L = ( W + w ) ( t2-t1)/x = (1458 + 456) ( 19.2-13,25)/0.945 = 12.051 k cal g-1 ½M LCV = 12051 – 8x0.09x586 = 11.629 k cal g-1 ½M 2. a) Give reason

i) The secondary reaction taking place in a dry cell is not a electrochemical reaction It is the conversion of Zn into diammine Zn (II) chloride. So it do not contribute towards the overall NH4+(aq) + OH-(aq) → NH3(g) + H2O (l)

Zn2+(aq)+2NH3(s)+ 2 Cl - →[Zn(NH3)2 Cl2] 1M

ii) Due to overcharging electrolysis of water will take place which results in the accumulation of hydrogen and oxygen leading to explosion of the cell. If kept in a partially discharged condition sulphatation will take place. 1M b) i)Explanation of function of anodic inhibitor with with an example 1M

Explanation of functions of 2 types of cathodic inhibitor with an example each 2M

ii) Example and function of a salt bridge 1 M c) i) Definition of electroless plating ½M The catalytic metals such as Ni, Co, Steel, Pd etc., do not require any surface preparation before electro less plating on them. Non catalytic metals such as Cu, brass, Ag etc., need activation. This can be done by dipping in palladium chloride solution.Non conductors like glass, plastics, etc., are first activated in a solution of SnCl2 and HCl.After rinsing its immersed in a solution of PdCl2 and HCl. This treatment yields a thin layer of Pd on the treated surface. 1½ M

Styrene butadiene rubber(SBR): It is prepared by addition polymerization of styrene( 75%) and 1,3 butadiene( 25%) ½M

(i) It is used as a plastic as well as fibre.

(ii) This is used to produce tyre cord.

(iii)It is used to make mono filaments and roaps.

(iv) Nylon 6,6 is used to manufacture articles like brushes and bristles.

Preparation of SBR

H2C CH

+ H2C CH CH CH2 n x n H2C CH CH CH2

x H2C CH

n

Uses:

Mainly used for the manufacture of motor tyres.

Other uses of this elastomer are floor tiles, shoe soles, gaskets, foot-wear components,

wire and cable insulations, carpet backing, adhesives, tank-lining, etc.,

3. a) Give reason: i) Mentioning 2 types of cathodic reactions in aerated acid soulutions ½M Equations ½M ii) Reason with proper explanation regarding passivating potential 1M

b) i) Development of electrode potential in a glass electrode: The glass is a partially hydrated aluminosilicate containing sodium or calcium ions. The hydration of a pH sensitive glass membrane involves an ion-exchange reaction between singly charged cations in the interstices of the glass lattice and protons from the solution. The ion-exchange reaction can be written as

H+ + Na+ <=====> Na+ + H+ Solution glass solution glass ½M

Explanation for development of potential ½M. Development of electrode potential of glass electrode:

The overall potential of the glass electrode has three components.

The boundary potential b, which varies with the pH of the analyte solution. It is made up of two potentials, E1 & E2 which develop at the two surface of the glass membrane i.e. the potential developed at the inner glass surface & the potential developed at the outer glass surface.

Eb = E1-E2 _______________________ (1) Where Eb is the boundary potential E1 = potential developed at the interface between the exterior of the glass and the analyte solution

E2 = Potential developed at the interface between the internal solution and the interior of the glass. The boundary potential is related to the concentration of hydrogen ion in each of the solution by the Nernst-like equation.

Eb = E1 – E2 = 0.0592 log Cl / C2 _________________ (2) Where C1 = concentration of the analyte solution C2 = concentration of the internal solution For a glass pH electrode the hydrogen ion concentration of the internal solution is held constant. So eqn. (2) simplifies to

Eb = K + 0.0592 log C1 __________________(3) 1M K – 0.0592 pH where K = - 0.0592 log C 2

The boundary potential is then a measure of the hydrogen ion concentration of the external solution. 2) The potential of the internal Ag/AgCl reference electrode. E Ag/AgCl. 3) A small unpredictable contribution called the asymmetry potential, E asym. The sources of the symmetry potential include the following. (i) Differing conditions of strain in the two glass surfaces during manufacture (ii) Mechanical abrasion on the on the outer surface during use (iii) Chemical etching of the outer surface during use. ½M

The asymmetry potential changes slowly with time. The glass electrode potential can be written in the equation form as

EG = Eb + EAg/ AgCl + E asym __________________ (4) Substitution of eqn – (3) for Eb, gives EG = K+0.0592 log C1 + EAg/AgCl + E asym = K – 0.0592 log pH + E Ag/AgCl + E asym ___(5) or EG = Eo

G – 0.0592PpH __________________(6) where Eo

G = K + EAg/AgCl + E asym.

a combination of three constant terms = constant ½M ii) pH = Ecell / 0.0592

= 0.34/0.0592 = 5.74. 1M

c) i) Mechanism of petroleum knocking 1M Prevention 1M ii) Explanation for suspension polymerization 1½M Any two differences between suspension and emulsion polymerization ½M 4. a) Reason: i) Lower in C.V due to volatile matter ½M Lower in C.V due to ash ½M ii) Reason 1M b) i) Cell Scheme:

Cd/Cd(OH)2,KOH,Ni(OH)2, Ni(OH)3/Ni ½M

Electrode reactions Anode:

Cd(OH)2(s)+2e-→ Cd(s) +2OH-(aq) ½M

Cathode: 2Ni(OH)2(s) +2OH-(aq)→2Ni(OH)3(s)+2e- ½M

Net: 2Ni(OH)2(s)+Cd(OH)2(s)→2Ni(OH)3(s)+ Cd(s) ½M

ii) Any four requirements of the fuel cell 1M Any two merits and demerits 1M c) i)Explanation of caustic embrittlement with equations 2M ii) Definition of Tg ½M Comparison of Tg values with structure 1 ½M 5. a)Give reason: i) Reason with proper explanation 1M ii) Reason with suitable explanation 1M

b) i) ∆G = -nFE However all electrochemical reactions are accompanied by

decrease in free energy of the system. Thus

, -∆G = -nFE Hence e.m.f of the cell is positive 1M ΔH = nF[T(δ E/ δT)P –E] = 2 X 96500 ( -2.952x10-3 x298 - 0.7653) = -2 x 96500x 1.6444 = -317.48 k J K-1 . ½M

ΔS = nF (δE / δT) P

= -2 x 96500x 2. 952x10-3

= -0.5695 kJ ½M

ii) Stucture Property relationship with respect ot plastic deformation and Chemical resistance 2M c) i) Detailed procedure for ultimate analysis of coal of determination of carbon and hydrogen with calculation steps. 2M

Percentage of nitrogen = Volume of acid used × Normality of acid ×1.4 Weight of coal taken

= 43.75 x 0.1x1.4/ 1.56 = 3.92% 1M Percentage of sulphur:

Wt. of BaSO4 obtained × 32 × 100 Wt. of coal taken × 233

= 0.1755 x32x100/ 2.60 x 233 = 0.9270 % 1M 6. a) Give reason i) Explanation with equation 1M ii) Explanation for differential areation corrosion 1M b) i) Explanation for the effect of two parameters on the rate of corrosion 1 mark

each 2M ii) Tacticity : Def ½M Three different stuctural configuration of polypropylene 1 ½M c) Origin of single electrode potential. 1½M Explanation of the galvanization 2M Reason ½M