first ia chemistry solution - pesitsouth.pes.edupesitsouth.pes.edu/pdf/2018/sh/sh_17che22_f,g,h,i...

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PESIT Bangalore South CampusHosur road, 1km before ElectronicCity, Bengaluru

Department of

BE II semester

CONTINUOUS Date : -26-02-2018 Subject & Code : Engineering Chemistry

Name of faculty :Dr AB, Prof PN, Dr RVM

Engineering Chemistry Solution

1 a What is electrode potential? Dthermodynamic parameters. Answer: Definition: The electrical potential developed at the interface of the metal and its solution due to

Helmholtz electrical double layer is called single electrode potential.

Derivation of Nerns’t Equation

The electrical potential developed at the interface of the metal and its solution due to Helmholtz

electrical double layer is called s

from Nerns't equation.

Nerns’t equation can be derived on the thermodynamic consideration.

Consider a general redox reaction:

Mn+ + ne- ═══ M

Oxidized form reduced form

For a reversible reaction the relationship between the free energy change (Δ G) and equilibrium

constant ‘k’ is given by Vant Hoff isotherm

ΔG = ΔGo + RT loge or -ΔG = -ΔGo - RT loge

[M] ΔG = ΔGº + RT loge [M +n

Where ΔGº = standard free energy

-ΔGº= Decrease in free energy accompanying the same process when the reactants and

Products of the reaction are in their standard states of unit activity.

K= Reaction quotient of the activities of the products and r

of the reaction.

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PESIT Bangalore South CampusHosur road, 1km before ElectronicCity, Bengaluru -100

Department of Basic Science and Humanities

CONTINUOUS INTERNAL EVALUATION

Engineering Chemistry – 17CHE22

Dr RVM and Prof. BP

Engineering Chemistry Solution PART 1

is electrode potential? Derive an expression for the potential developed at the interface

Definition: The electrical potential developed at the interface of the metal and its solution due to

ouble layer is called single electrode potential.

Derivation of Nerns’t Equation-Equation for single electrode potential:


electrical double layer is called single electrode potential. Single electrode potential can be calculated

Nerns’t equation can be derived on the thermodynamic consideration.

Consider a general redox reaction:

Oxidized form reduced form


constant ‘k’ is given by Vant Hoff isotherm

[Reduced form] [Oxidized form]

e K

[M]

+n] ree energy [ΔGº = RT loge K]

º= Decrease in free energy accompanying the same process when the reactants and

Products of the reaction are in their standard states of unit activity.

K= Reaction quotient of the activities of the products and reactants at any given stage

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PESIT Bangalore South Campus

EVALUATION TEST -1 Marks: 60

Sec : F,G,H,I and J

Marks

an expression for the potential developed at the interface using

Definition: The electrical potential developed at the interface of the metal and its solution due to


ingle electrode potential. Single electrode potential can be calculated


(1)

º= Decrease in free energy accompanying the same process when the reactants and

eactants at any given stage

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In a reversible reaction, electrical energy is produced at the expense of free energy. i.e., free

energy decreases.

If E is the electrode potential of the electrode and electrode reaction involves transfe

electrons, i.e. nF coulombs, Therefore the electrical work available from the electrode is nFE Volt

coulombs (or Joules). Hence free energy decrease of the system ΔG is given by the expression,

nFE.

nEF = -ΔG ΔG = - nEF,

nE°F = ΔGº Δ°G = -

Substituting in (1) nEºF =

- nEF = - nEº F + RT log

n = valency of metal ion E = single electrode potential

Eº = standard electrode potential F= Faraday = 96,500 coulombs -nEF = - nEº F + RT loge [M

(The concentration of metal is Unit. i.e., M= 1)

-nEF = - nEº F - RT loge [M +n]

nEF = nEº F + RT loge[M +n]

Dividing by nF

E = Eº + RT loge[M +n]

nF

E = E º + RT 2.303 log10 [M +n]

nF

Substituting R, T, F we get

E = Eº + 0.059 log 10 [M +n]

n

Where R= gas constant [8.314Jk

[M n+] = metal ion concentration

Concentration & Temperature dependency of single electrode poten

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If E is the electrode potential of the electrode and electrode reaction involves transfe


coulombs (or Joules). Hence free energy decrease of the system ΔG is given by the expression,

nEF,

n EºF

Substituting in (1) nEºF = - ΔGº

[M] nEº F + RT loge

[M+n] E = single electrode potential

Eº = standard electrode potential F= Faraday = 96,500 coulombs 1

[M +n]

(The concentration of metal is Unit. i.e., M= 1)

]

]

Where R= gas constant [8.314Jk-1 mol], T= lab temperature [298k]

] = metal ion concentration

Concentration & Temperature dependency of single electrode potential:

E



If E is the electrode potential of the electrode and electrode reaction involves transfer of ‘n’


coulombs (or Joules). Hence free energy decrease of the system ΔG is given by the expression, -ΔG =

tial: Nerns’t equation for single

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electrode potential is:

E = E º + RT 2.303 log10 [M +n

nF

From the above equation it is evident that Electrode potential increases as the Temperature &

Concentration increases.

Nerns’t equation can also be used to calculate the emf of a cell

aA + bB ═══ cC + dD

The Nerns’t equation for the emf of the cell is

E cell = E0cell - 2.303 log [C] c[D]

nF [A] a[B]

E cell = E0cell - 0.0591 log [C] c

n [A] a[B]

When n is the number of electrons transferred during the cell reaction and E

the cell.

b How do you obtain polycarbonates from itsAnswer:

Polycarbonate (PC) Polycarbonates are linear polyesters of carbonic acid with aliphatic or aromatic polyols. Polymers containing carbonate groups

Synthesis Polycarbonate can be synt

diphenyl carbonate.

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+n]


used to calculate the emf of a cell

═══ cC + dD

The Nerns’t equation for the emf of the cell is

[D] d

[B] b

c[D] d at 298K

[B] b

When n is the number of electrons transferred during the cell reaction and E

obtain polycarbonates from its monomers? Write any three properties and application.

Polycarbonates are linear polyesters of carbonic acid with aliphatic or aromatic polyols. Polymers containing carbonate groups

O

C OO

Polycarbonate can be synthesized by the condensation reaction of Bisphenol A (polyol) with

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When n is the number of electrons transferred during the cell reaction and E0cell is the standard emf of

hree properties and application.

Polycarbonates are linear polyesters of carbonic acid with aliphatic or aromatic polyols.

hesized by the condensation reaction of Bisphenol A (polyol) with

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Bisphenol- A is obtained by the reaction between phenol and acetone in presence of strong HCl. Diphenyl carbonate can be prepared by the reaction between phenol and phos

alkaline medium in presence of tertiary amine as catalyst.

Properties • It melts at 2650C and has very high impact and tensile strength • It is resistant to water and many organic compounds but alkalies will slowly hydrolyse• It is transparent plastic • It is soluble in organic solvent like methylene chloride

Application • Being a good electrical insulator and having heat resistance and flame retardant properties, it is

used in various products associated with electrical and telecommunications h• It is used in the production of compact disc and DVDs• It can be laminated to make bullet proof glass• PC is used in the manufacture of variety of lenses with much higher impact and scratch than

glass • It is used in construction industry e.g. for dom

2 a From vinyl chloride monomer synthesizes PVC and describes

Answer: Mechanism of polymerizationexample.

Free radical reaction can be divided into three steps namely• Initiation • Propagation • Termination

One of the most common and useful reaction for making polymers is free radical polymerization. It is used to make polymers from vinyl monomers, that is, from small molecu

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A is obtained by the reaction between phenol and acetone in presence of strong HCl. Diphenyl carbonate can be prepared by the reaction between phenol and phosalkaline medium in presence of tertiary amine as catalyst.

C and has very high impact and tensile strength It is resistant to water and many organic compounds but alkalies will slowly hydrolyse

It is soluble in organic solvent like methylene chloride

Being a good electrical insulator and having heat resistance and flame retardant properties, it is used in various products associated with electrical and telecommunications hIt is used in the production of compact disc and DVDs It can be laminated to make bullet proof glass PC is used in the manufacture of variety of lenses with much higher impact and scratch than

It is used in construction industry e.g. for domelights, flat or curved glazing, and sound walls

monomer synthesizes PVC and describes free radical reaction mechanism.

Mechanism of polymerization- free radical mechanism taking vinyl chloride as an

al reaction can be divided into three steps namely

One of the most common and useful reaction for making polymers is free radical polymerization. It is used to make polymers from vinyl monomers, that is, from small molecules containing carbon

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A is obtained by the reaction between phenol and acetone in presence of strong HCl. Diphenyl carbonate can be prepared by the reaction between phenol and phosogene (COCl2) in

It is resistant to water and many organic compounds but alkalies will slowly hydrolyse

Being a good electrical insulator and having heat resistance and flame retardant properties, it is used in various products associated with electrical and telecommunications hardware

PC is used in the manufacture of variety of lenses with much higher impact and scratch than

elights, flat or curved glazing, and sound walls

free radical reaction mechanism.

free radical mechanism taking vinyl chloride as an

One of the most common and useful reaction for making polymers is free radical polymerization. It is les containing carbon-carbon

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double bonds. Initiation:The first step of which involves two reactions. The first is the spontaneous decomposed of an initiator into free radicals. A variety of peroxides act as initiator such as benzoyl peroxide.

Propagation:

The radical side of the first monomer unit attacks the double bond of the second monomer unit as shown

This process involves a continuing attack on fresh monomer molecule which, in turn, keeps successively adding to the growing chain one after

Where n is the number of monomer unit added up in the chain growth

Termination: Here the two growing chains unit by coupling of the unpaired electrons.a) By combination of free radicals

b) By disproportionation of free radicals

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The first step of which involves two reactions. The first is the spontaneous decomposed of an initiator into free radicals. A variety of peroxides act as initiator such as benzoyl peroxide.


This process involves a continuing attack on fresh monomer molecule which, in turn, keeps successively adding to the growing chain one after the other.

Where n is the number of monomer unit added up in the chain growth

Here the two growing chains unit by coupling of the unpaired electrons.

By combination of free radicals

By disproportionation of free radicals

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The first step of which involves two reactions. The first is the spontaneous decomposed of an initiator into free radicals. A variety of peroxides act as initiator such as benzoyl peroxide.


This process involves a continuing attack on fresh monomer molecule which, in turn, keeps successively

Where n is the number of monomer unit added up in the chain growth.

Here the two growing chains unit by coupling of the unpaired electrons.

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b Discuss concentration cell’s construction and obtain an expression for

Answer:

Concentration cell

Same electrodes but of different electrolyte concentrations. Concentration cell formed by the

combination of same electrode dipped

The above reaction, shows that there is no net chemical reaction but involves only transfer of Zn2+ ions from solution of higher concentration c

Consider the above cell; the electrode potential is given by Nerns’t equation

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s concentration cell’s construction and obtain an expression for EMF of the


combination of same electrode dipped into same electrolyte of different concentration

The above reaction, shows that there is no net chemical reaction but involves only transfer of ions from solution of higher concentration c2 to solution of lower concentration c

ell; the electrode potential is given by Nerns’t equation

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EMF of the concentration cell.


into same electrolyte of different concentration

The above reaction, shows that there is no net chemical reaction but involves only transfer of to solution of lower concentration c1.

ell; the electrode potential is given by Nerns’t equation

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Applications From this expression, the EMF of the concentration cell can be calculated. concentration cells are used in the determination of valency of complex ions concentration cells are used

PbSO4, BaSO4 etc.,

3 a Define the following with suitable examples 1) Addition polymer 2) Condensation polymerAnswer: Addition polymers:

The addition polymers are formed bor triple bonds, e.g., the formation of polythene from ethene and polypropene from propene. However, the addition polymers formed by the polymerisation of a single monomeric species are known ahomopolymers, e.g., polythene.

nCH

Ethene

Condensation polymers the condensation polymers are formed by repeated condensation reaction between two different bi-functional or trithe elimination of small molecules such as water, alcohol, hydrogen chloride, etc. take place. The

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Zn/ZnSO4(C1) ZnSO4(C2)/Zn

Concetration cell is represented as follows

E1E2

Anode Cathode

From this expression, the EMF of the concentration cell can be calculated. concentration cells are used in the determination of valency of complex ionsconcentration cells are used in the determination of solubility of sparingly soluble salt like AgCl,

PART 2 Define the following with suitable examples 1) Addition polymer 2) Condensation polymer

are formed by the repeated addition of monomer molecules possessing double or triple bonds, e.g., the formation of polythene from ethene and polypropene from propene. However, the addition polymers formed by the polymerisation of a single monomeric species are known ahomopolymers, e.g., polythene.

nCH2 CH2nCH2=CH2

EthenePolyethene

he condensation polymers are formed by repeated condensation reaction functional or tri-functional monomeric units. In these polymerisation react

the elimination of small molecules such as water, alcohol, hydrogen chloride, etc. take place. The

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concentration cells are used in the determination of valency of complex ions in the determination of solubility of sparingly soluble salt like AgCl,

Define the following with suitable examples 1) Addition polymer 2) Condensation polymer

y the repeated addition of monomer molecules possessing double or triple bonds, e.g., the formation of polythene from ethene and polypropene from propene. However, the addition polymers formed by the polymerisation of a single monomeric species are known as

he condensation polymers are formed by repeated condensation reaction functional monomeric units. In these polymerisation reactions,

the elimination of small molecules such as water, alcohol, hydrogen chloride, etc. take place. The

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examples are terylene (dacron), nylon 6, 6, nylon 6, etc. For example, nylon 6, 6 is formed by the condensation of hexamethylene diamine with adipic ac

(CHNH

(CH2)4 CC

[

OOHHOO

Adipic acid

b What is a reference electrode? How can you construct calomel electrode? Write its electrode reaction and advantages. Answer: Reference electrodes: The single electrode potential cannot be directly measured. Hence aelectrode of known potential is used to measure the single electrode potential. The standard electrode whose potential is known is called reference electrode.

Construction

The electrode consists ofcontact with a paste of mercury,

Mercury(I) chloride (calomel),solution of potassium chlorideon via a porous frit, fibre

Vessel is completely filled with 1M KCl/0.1M KCl/ saturated solution of KCl The value of standard reduction potential of calomel depends upon the concentration of KCl.

The standard reduction potential of calomel electrodFor saturated KCl = + 0.244 v

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examples are terylene (dacron), nylon 6, 6, nylon 6, etc. For example, nylon 6, 6 is formed by the condensation of hexamethylene diamine with adipic acid.

(CH2)6 NH

(CH2)4C

O

C

O

(CH2)6N N

]

OOH + H2H2

Hexamethelene diamine

Nylon-66

n + nH

reference electrode? How can you construct calomel electrode? Write its electrode reaction and

The single electrode potential cannot be directly measured. Hence aelectrode of known potential is used to measure the single electrode potential. The standard electrode whose potential is known is called reference electrode.

of two concentric glass tubes, the inner one ofmercury,

(calomel), and potassium chloride. This is in contactchloride in the outer tube which itself makes contact

fibre or ground glass sleeve Vessel is completely filled with 1M KCl/0.1M KCl/ saturated solution of KClThe value of standard reduction potential of calomel depends upon the concentration of KCl. The standard reduction potential of calomel electrode is as follows: For saturated KCl = + 0.244 v

E


examples are terylene (dacron), nylon 6, 6, nylon 6, etc. For example, nylon 6, 6 is formed by the

nH2O

reference electrode? How can you construct calomel electrode? Write its electrode reaction and

The single electrode potential cannot be directly measured. Hence a standard electrode of known potential is used to measure the single electrode potential. The standard electrode

of which contains mercury in

contact with a contact with the sample soluti

Vessel is completely filled with 1M KCl/0.1M KCl/ saturated solution of KCl The value of standard reduction potential of calomel depends upon the concentration of KCl.

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For 1M KCl = + 0.280 vFor 0.1 M KCl = + 0.388 vThe electrode is represented as Hg (Electrode Reactions

Advantages of calomel electrode

• It is very simple to construct and easy to operate.

• The potential developed remains constant for long time.

• The electrode potential does not vary with temperature.

4 a

Define glass transition temperature. Answer: Glass Transition Temperature

Amorphous polymers do not have specific melting point. At low temperature they are hard, brittle, rigid and glassy and at high temperature rubber and leathery. The temperature at which this transiis called glass transition temperature (T

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= + 0.280 v = + 0.388 v

The electrode is represented as Hg (l), Hg2Cl2 (s) /Cl-

Advantages of calomel electrode:

It is very simple to construct and easy to operate.

The potential developed remains constant for long time.

The electrode potential does not vary with temperature.

Define glass transition temperature. Explain all the factors influencing glass transition temperature.

Glass Transition Temperature

Amorphous polymers do not have specific melting point. At low temperature they are hard, brittle, rigid and glassy and at high temperature rubber and leathery. The temperature at which this transiis called glass transition temperature (Tg).

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sition temperature.

Amorphous polymers do not have specific melting point. At low temperature they are hard, brittle, rigid and glassy and at high temperature rubber and leathery. The temperature at which this transition occurs

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Factors influencing glass transition temperatureFlexibility Higher the flexibility of the backbone chain of the polymer, lower will be its glass transition temperature. Rigid groups like aromatic orreduce the flexibility of the chain and hence increases.Glass transition temperature is inversely related to theflexibility of a polymeric chain. For example Tpolyester is 1000 C.

Inter molecular forces Presence of intermolecular forces in the polymer chain due to polar groups, dipoles etc restrict the molecular mobility and hence increase glass transition temperature-180C whereas in case of nylon 6,6 (contains polar groups) is 57

Molecular mass Glass transition temperature increases with increase in molecular mass up to 20000 and above there is no change. Branching & Cross linking A small amount of branchin

glass transition temperature. On the other hand high density of branching brings the polymer chains closer lowers the free

volume, thus reducing the chain mobility. As a result TStereo regularity Glass transition is depending upon the stereo regularity of the polymer. For example Syndiotactic

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Factors influencing glass transition temperature

Higher the flexibility of the backbone chain of the polymer, lower will be its glass transition temperature. Rigid groups like aromatic or cyclic rings or bulky side groups in the polymeric chain reduce the flexibility of the chain and hence increases.Glass transition temperature is inversely related to theflexibility of a polymeric chain. For example Tgof polyethylene is -

Presence of intermolecular forces in the polymer chain due to polar groups, dipoles etc restrict the molecular mobility and hence increase glass transition temperature. For example T

C whereas in case of nylon 6,6 (contains polar groups) is 570C.

Glass transition temperature increases with increase in molecular mass up to 20000 and above there is

A small amount of branching tends to give rise to free volume and as such will tend to lower glass transition temperature. On the other hand high density of branching brings the polymer chains closer lowers the free volume, thus reducing the chain mobility. As a result Tg increases.

Glass transition is depending upon the stereo regularity of the polymer. For example Syndiotactic

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Higher the flexibility of the backbone chain of the polymer, lower will be its glass transition cyclic rings or bulky side groups in the polymeric chain

reduce the flexibility of the chain and hence increases.Glass transition temperature is inversely related to -1100 C whereas in case of

Presence of intermolecular forces in the polymer chain due to polar groups, dipoles etc restrict the For example Tg of polypropylene is

Glass transition temperature increases with increase in molecular mass up to 20000 and above there is

g tends to give rise to free volume and as such will tend to lower

On the other hand high density of branching brings the polymer chains closer lowers the free

Glass transition is depending upon the stereo regularity of the polymer. For example Syndiotactic

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polymer>Atactic polymer>Isotactic Polymer

Significance of Tg

The value of Tg is a measure of flexibility of a polymer and predicts its stress.

Knowledge of Tg and Tm

The value of Tg gives an idea of the thermal expansion, heat capacity, refractive index, electrical and mechanical properties of the polym

b What are adhesives? Write the equation for the synthesis of epoxy applications. Answer:

Epoxy Resins Good adhesives for variety of materials They contain The epoxy group also known as oxirane, contains an O Commercially epoxy resins are known as ‘Araldite or Epon

Synthesis • Epoxy resins can be obtained by the condensation reaction between bisphenol A and

Epichlorohydrin

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polymer>Atactic polymer>Isotactic Polymer

is a measure of flexibility of a polymer and predicts its

m is useful in choosing right temperature range for fabrication.The value of Tg gives an idea of the thermal expansion, heat capacity, refractive index, electrical and mechanical properties of the polymer.

Write the equation for the synthesis of epoxy resin; give any three properties and

Good adhesives for variety of materials

The epoxy group also known as oxirane, contains an O atom bonded with carbon atomsCommercially epoxy resins are known as ‘Araldite or Epon

R CH CH

O

Epoxy resins can be obtained by the condensation reaction between bisphenol A and

E


is a measure of flexibility of a polymer and predicts its response to Mechanical

is useful in choosing right temperature range for fabrication. The value of Tg gives an idea of the thermal expansion, heat capacity, refractive index, electrical

any three properties and

atom bonded with carbon atoms

Epoxy resins can be obtained by the condensation reaction between bisphenol A and

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HO

CH

C

CH

CH2 CH

O

O

n

CH2

Properties Polar nature High resistance Low shrinking on curing During polymerization do not leads to voides as no volatile by product is produced on curing Good insulating property

Application Used as adhesives for many surfaces like glass, metals, wood e Surface coating as skid resistance Reinforced plastics, components of aircrafts and automobiles Laminating material Crease and shrinkage resistance to fabrics

5 a Discuss the construction, working princiAnswer: Glass electrode

Concept: Whenever a thin glass membrane is in contact with two solutions of different H+ ion concentration, a potential arises across the membrane (glass), the potential developed depends upon the H+ ion concentration of the test solution. The potential of glass electrode is given by Nerns’t equation.

EG = E°G + 0.059log10[H

n

Where EºG is standard electrode potential of glass electrode and it is constant for the given electrode. Its value is + 0.456 v at 25° C.

Construction: A glass electrode consists of a long glass tube with a thin walled bulb atglass containing 22% Na2O, 6% CaO& 72% SiOis used for the purpose. This glass can specialand an Ag-AgCl electrode is immersed into a solution. The platinum wire is provided for external contact.

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CH3

C OH

CH3

CH2 CH CH2Cl

O

+

CH3

C

CH3

OH

O CH2 CH OCH2

CH3

C

CH3

NaOH

-HCl

Epoxy resin

n

Low shrinking on curing During polymerization do not leads to voides as no volatile by product is produced on curingGood insulating property

Used as adhesives for many surfaces like glass, metals, wood etc Surface coating as skid resistance Reinforced plastics, components of aircrafts and automobiles

Crease and shrinkage resistance to fabrics PART 3

Discuss the construction, working principle, electrode reactions and the advantages

Whenever a thin glass membrane is in contact with two solutions of different H+ ion concentration, a potential arises across the membrane (glass), the potential developed depends upon the

tration of the test solution. The potential of glass electrode is given by Nerns’t equation.

[H+]

is standard electrode potential of glass electrode and it is constant for the given electrode.

A glass electrode consists of a long glass tube with a thin walled bulb atO, 6% CaO& 72% SiO2 of low melting point and high electrical conductance

is used for the purpose. This glass can specially sense hydrogen ions. The bulb containing 0.1M HCl AgCl electrode is immersed into a solution. The platinum wire is provided for external

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CH

O

O CH2CH2

During polymerization do not leads to voides as no volatile by product is produced on curing

ages glass electrode.

Whenever a thin glass membrane is in contact with two solutions of different H+ ion concentration, a potential arises across the membrane (glass), the potential developed depends upon the

tration of the test solution. The potential of glass electrode is given by Nerns’t equation.

is standard electrode potential of glass electrode and it is constant for the given electrode.

A glass electrode consists of a long glass tube with a thin walled bulb at one end. Special of low melting point and high electrical conductance

ly sense hydrogen ions. The bulb containing 0.1M HCl AgCl electrode is immersed into a solution. The platinum wire is provided for external

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The electrode is represented as Ag/Agcl/0.1MHCl/glass.

Electrode reactions: The electrode

H+ + Na+Gl-

Advantages of glass electrode:

a) It is very easy to construct and simple to operate.b) The potential developed remains constant for long time.c) This electrode can be used with very smald) This electrode can be used even in the presence of oxidized impurities, reducing impurities,

poison molecules etc., e) The wide pH range from 0 to 14 can be measured using glass electrode.

b Discuss as to how we can determinAnswer:

Determination of standard electrode po

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The electrode reaction is as follows:

Na+ + H+Gl-

Advantages of glass electrode:

It is very easy to construct and simple to operate. The potential developed remains constant for long time. This electrode can be used with very small amount of the test solution.This electrode can be used even in the presence of oxidized impurities, reducing impurities,

The wide pH range from 0 to 14 can be measured using glass electrode.determine unknown metal electrode potential using standard

Determination of standard electrode potential using calomel electrode

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l amount of the test solution. This electrode can be used even in the presence of oxidized impurities, reducing impurities,

The wide pH range from 0 to 14 can be measured using glass electrode. ndard calomel electrode? 6

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Copper electrode is constituted and it is coupled into calomel electrode internally by means of salt bridge and externally through potentiometer.

The EMF of the cell is determined experimentally and at the same time, the direction of flow of current. The voltmeter shows that the current flows from Cu to calomel electrode.

Therefore Cu electrode acts as catIUPAC system the cell is represented as follows:

The anode and cathode of the cell can be identified by connecting the electrodes of the cell to a voltmeter.

In any galvanic cell current flows from By observing the deflection in the voltmeter the sign can be assigned to the given electrodes in

the cell. 6 a

What is an elastomer? Discuss the synthesis properties and applications of polyurethane.Answer: Polyurethanes Polyurethanes are characterized by the presence of urethane linkages ( They are produced by reacting hydroxyl compounds with polyisocyanates It resembles polyamides (

chain makes them more fl

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Copper electrode is constituted and it is coupled into calomel electrode internally by means of ge and externally through potentiometer.

The EMF of the cell is determined experimentally and at the same time, the direction of flow of current. The voltmeter shows that the current flows from Cu to calomel electrode.Therefore Cu electrode acts as cathode and calomel electrode acts as anode. According to IUPAC system the cell is represented as follows:

The anode and cathode of the cell can be identified by connecting the electrodes of the cell to a

In any galvanic cell current flows from cathode and anode. By observing the deflection in the voltmeter the sign can be assigned to the given electrodes in

What is an elastomer? Discuss the synthesis properties and applications of polyurethane.

nes are characterized by the presence of urethane linkages (They are produced by reacting hydroxyl compounds with polyisocyanatesIt resembles polyamides (-NHCO-) in their structure in presence additional “O” atom in the chain makes them more flexible

E


Copper electrode is constituted and it is coupled into calomel electrode internally by means of

The EMF of the cell is determined experimentally and at the same time, the direction of flow of current. The voltmeter shows that the current flows from Cu to calomel electrode.

hode and calomel electrode acts as anode. According to

The anode and cathode of the cell can be identified by connecting the electrodes of the cell to a

By observing the deflection in the voltmeter the sign can be assigned to the given electrodes in

What is an elastomer? Discuss the synthesis properties and applications of polyurethane.

nes are characterized by the presence of urethane linkages (-NH-CO-O-) They are produced by reacting hydroxyl compounds with polyisocyanates

) in their structure in presence additional “O” atom in the

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C

O

[

Synthesis It is synthesised by the poly addition reaction between diisocynate and diols or triols. During addition reaction the hydrogen atoms of OH groups migrate then add to the nitrogen

atoms of diisocynate. Hence it is referred as rearrangement addition polymerization reaction

CO

O[

Alkyl Diisocyanate

Properties The melting point of PU is less than that of corresponding polyamides Higher the flexibility of PU due to the presence of additional O atom Thermally they are less stable High scratch resistance

Applications 1. PU coatings are used in gymnasium and dancing floor because of high abrasion resistance2. PU foams are used as cushions for furniture and automobiles3. PU rigid foams are used to reinforce hollow stru4. PU are used as soles for foot wares, tyre threads and industrial wheel5. PU fabrics are used as light weight garments and swim suits, because of stretching property6. PU elastomers are used as gaskets, seals because of their resistance to oil and

b Write the equation for the synthesis of: PMMA and Silicon rubber

Answer:

Synthesis properties and their applicationsPolymethyl Methacrylate (PMMA) or Plexi Glass

• It is an addition polymer• Plexi glass is obtained by radical polymerization in bulk, emulsion or suspension from the

monomer methyl methacrylate (MMA) using hydrogen peroxide as initiatormonomer is obtained from acetone.

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C CNN

HH

(R) O

O

O

O

(R) ]n

It is synthesised by the poly addition reaction between diisocynate and diols or triols. During addition reaction the hydrogen atoms of OH groups migrate then add to the nitrogen

it is referred as rearrangement addition polymerization reaction

N R N

H

ROC + HODiol

N RC N ROO C O

O OH

Alkyl Diisocyanate

The melting point of PU is less than that of corresponding polyamidesHigher the flexibility of PU due to the presence of additional O atom

they are less stable

PU coatings are used in gymnasium and dancing floor because of high abrasion resistancePU foams are used as cushions for furniture and automobiles PU rigid foams are used to reinforce hollow structural units PU are used as soles for foot wares, tyre threads and industrial wheelPU fabrics are used as light weight garments and swim suits, because of stretching propertyPU elastomers are used as gaskets, seals because of their resistance to oil and

Write the equation for the synthesis of: PMMA and Silicon rubber, their properties and

Synthesis properties and their applications Polymethyl Methacrylate (PMMA) or Plexi Glass

It is an addition polymer lass is obtained by radical polymerization in bulk, emulsion or suspension from the

monomer methyl methacrylate (MMA) using hydrogen peroxide as initiatormonomer is obtained from acetone.

E


n

It is synthesised by the poly addition reaction between diisocynate and diols or triols. During addition reaction the hydrogen atoms of OH groups migrate then add to the nitrogen

it is referred as rearrangement addition polymerization reaction.

OH

O ] n

The melting point of PU is less than that of corresponding polyamides Higher the flexibility of PU due to the presence of additional O atom

PU coatings are used in gymnasium and dancing floor because of high abrasion resistance

PU are used as soles for foot wares, tyre threads and industrial wheel PU fabrics are used as light weight garments and swim suits, because of stretching property PU elastomers are used as gaskets, seals because of their resistance to oil and corrosive wheels

, their properties and applications.

lass is obtained by radical polymerization in bulk, emulsion or suspension from the monomer methyl methacrylate (MMA) using hydrogen peroxide as initiator at 60-700. The

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BE II semester

H2C

Properties • ItsTg1050 C. Colorless, transparent hard solid at room temperature.• Amorphous due the presence of bulky groups• Resistant to many chemicals but soluble in organic solvent like acetone and chlorinated

hydrocarbons and esters • Higher the optical clarity• It has a good dimensional stability

Applications • Due to its optical clarity it is used to make aircraft windows, signal boards etc• For Making artificial teeth and contact lens• Used in paints and adhesives• Making transparent bottles and wash basins.• Good substitute for glass but has poor scratch resistance

Silicone Rubber The silicones are a group of organo Each Si is occupied by organic groups such as

Synthesis Silicone rubbers are formed by the condensation polymerizatio

prepared from hydrolysis of dimethyl dichlorosilane. Depending on the chain length and degree of cross linking the polysilicones obtained may be

oils, greases or rubbery solids.

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C

CH3

COOCH3

CH2C

CH3

COOCH

( )n

Polymethyl methacrylate (PMMA)

H2O2

60-700 CEmulsion Polymerization

C. Colorless, transparent hard solid at room temperature. Amorphous due the presence of bulky groups Resistant to many chemicals but soluble in organic solvent like acetone and chlorinated hydrocarbons and esters Higher the optical clarity

dimensional stability

Due to its optical clarity it is used to make aircraft windows, signal boards etcFor Making artificial teeth and contact lens Used in paints and adhesives Making transparent bottles and wash basins.

lass but has poor scratch resistance

The silicones are a group of organo-silicon polymers containing Si-O backboneEach Si is occupied by organic groups such as –CH3

Silicone rubbers are formed by the condensation polymerization of dimethyl silanol which is prepared from hydrolysis of dimethyl dichlorosilane. Depending on the chain length and degree of cross linking the polysilicones obtained may be oils, greases or rubbery solids.

E


COOCH3

Polymethyl methacrylate (PMMA)

Resistant to many chemicals but soluble in organic solvent like acetone and chlorinated

Due to its optical clarity it is used to make aircraft windows, signal boards etc

O backbone

n of dimethyl silanol which is

Depending on the chain length and degree of cross linking the polysilicones obtained may be

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Department of

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Properties Depending on the chain length and Stable Repellent Non toxic Resistance

Applications As a sealing material in search As Insulating material As adhesives in Electronic industry Making boots at low T Artificial heart valves, tubing's for chemical and medical use Industrial and domestic gaskets As antiflatulent agent used in antacid products

7 a Explain the conduction mechanism of polyaniline.

Conduction Mechanism of PANI Conducting form of polyaniline is obtained EB is treated with HCl (1M) then it is protonated and form ES Then two nearby imine sites are protonated to form a bipolaron The bipolaron then undergoes a further rearrangement to form two polarons in which +ve

charges are delocalized as shown The resulting ES has delocalized +ve charges in polymer backbone which are responsible for

electrical conductivity The +ve charges are compensated by anions of the acid. Thus polymer as a whole is electrically neutral but contains

polymer structure which conducts an electric current This type of protonic acid doping increases the conductivity of PANI by 9

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Depending on the chain length and degree of cross linking the polysilicones

As a sealing material in search-light and aircraft engine

As adhesives in Electronic industry

, tubing's for chemical and medical use Industrial and domestic gaskets As antiflatulent agent used in antacid products

PART 4 Explain the conduction mechanism of polyaniline.

Conduction Mechanism of PANI Conducting form of polyaniline is obtained called EB EB is treated with HCl (1M) then it is protonated and form ES Then two nearby imine sites are protonated to form a bipolaron The bipolaron then undergoes a further rearrangement to form two polarons in which +ve charges are delocalized as shown in the recation scheme The resulting ES has delocalized +ve charges in polymer backbone which are responsible for

The +ve charges are compensated by anions of the acid. Thus polymer as a whole is electrically neutral but contains delocalized +ve charges on the polymer structure which conducts an electric current This type of protonic acid doping increases the conductivity of PANI by 9

E


degree of cross linking the polysilicones

The bipolaron then undergoes a further rearrangement to form two polarons in which +ve

The resulting ES has delocalized +ve charges in polymer backbone which are responsible for

delocalized +ve charges on the

This type of protonic acid doping increases the conductivity of PANI by 9-10 times.

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BE II semester

b The EMF of the cell Cd/CdSO4(0.01

the value of x. Answer

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(0.01M)// CdSO4 (xM)/Cd is 0.0295V at 298K. Writ

E


Write electrode reaction and find 6

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BE II semester

8 a The EMF of the cell Cu/Cupricnitrate (0.01M)//Cupric nitrate (0.10M) /CuWhat is the valency of Cu ions and write the electrode reactionAnswer: 2

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The EMF of the cell Cu/Cupricnitrate (0.01M)//Cupric nitrate (0.10M) /Cu was found to be 0.0295V at 298Kand write the electrode reaction?

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was found to be 0.0295V at 298K. 6

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BE II semester

b How do you determine the pH of the solution using glass electrode?Answer: Determination of pH of the solution using glass electrode

The glass electrode consists of a glass tube having a thin walled bulb at the bottom which contains 0.1M HCl.

A platinum wire is dipped into the acid solution to give electrical contact. This bulb is dipped into the test solution whose pH is to be determined. The resulting glass electrode is combined with the calomel electrode internally through a salt

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How do you determine the pH of the solution using glass electrode?

Determination of pH of the solution using glass electrode

The glass electrode consists of a glass tube having a thin walled bulb at the bottom which

platinum wire is dipped into the acid solution to give electrical contact. This bulb is dipped into the test solution whose pH is to be determined.The resulting glass electrode is combined with the calomel electrode internally through a salt

E


The glass electrode consists of a glass tube having a thin walled bulb at the bottom which

platinum wire is dipped into the acid solution to give electrical contact. This bulb is dipped into the test solution whose pH is to be determined. The resulting glass electrode is combined with the calomel electrode internally through a salt

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BE II semester

bridge and externally through a potentiometer. The EMF of the cell is determined experimentally and at the same time the direction of flow of

current is noted.

9 a Describe its synthesis properties andAnswer:

Kevlar Fiber • Kevlar is DuPont company’s brand name• Name Aromatic polyamide, Poly• MF[–CO-C6H4-CO-NH

Synthesis • By condensation of 1,4phenylene diamine and 1,4 benzenedicarbonyl chloride.

NH2H2N

NH

NH

1,4 phenylene diamine

Kevlar Fiber

Properties Tensile strength Modulus of elasticity Strength to weight ratio Chemical resistance Low co-efficient of thermal expansion Impact resistance, Cut, Textile, Flame, Low flexibility Heat

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xternally through a potentiometer. The EMF of the cell is determined experimentally and at the same time the direction of flow of

PART 5 Describe its synthesis properties and applications of Kevlar fiber.

evlar is DuPont company’s brand name Name Aromatic polyamide, Poly-paraphenyleneterepthalamide

NH-C6H4-NH-]n

By condensation of 1,4phenylene diamine and 1,4 benzenedicarbonyl chloride.

ClCl

OO

+

NH

-HCl

C C

O

C C

O

n

1,4 benzenedicarbonyl chloride

Kevlar Fiber

efficient of thermal expansion Impact resistance, Cut, Textile, Flame, Low flexibility

E


The EMF of the cell is determined experimentally and at the same time the direction of flow of

By condensation of 1,4phenylene diamine and 1,4 benzenedicarbonyl chloride.

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Applications Well known component of personal Armor such as combat helmets, b

ballistic vest Gloves, sleeves, jackets, chaps and other articles Inner lining in bicycle tires Nike used Kevlar in shoes and shoe laces It is substitute for Teflon Light weight boat hulls, aircraft panels, race cars, bridge structur

b Write note on structure property relationship of a polymer.Answer:

Structure property relationship of polymers• Polymers are known to exhibit wide variety of properties.• Some appear • Rigid • Hard • Strong • Stable

While others appear • Soft • Flexible • Largely extensible under the influence of stress• Show readily solubility and fusibility• Resistant to heat and solvent

Tensile Strength Based on the molecular mass the following relationship.

1. Low molecular mass are soft and gummy2. High molecular mass are tough and heat resistant3. By increasing molecular mass the impact strength increases certain e

constant. 4. Melt viscosity initially shows gradual increase then increases steeply with high molecular weight

Crystallinity The properties of polymers such as hardness, permeability, heat capacity etc The degree of crystallinity of a polymer depends on its structure and its configuration. Polymers made up of linear chains without much bulky groups increases crystallinity. For

example PE is more crystalline then polystyrene Polymer chains containing polar groups increase crystallinity. For Example nylon 6,6 showing

more crystallinity Higher crystallinity leads to Sharp MP Higher density, rigidity and strength

1 P E



Well known component of personal Armor such as combat helmets, b

Gloves, sleeves, jackets, chaps and other articles Inner lining in bicycle tires Nike used Kevlar in shoes and shoe laces It is substitute for Teflon Light weight boat hulls, aircraft panels, race cars, bridge structure, bullet proof vest etc

Write note on structure property relationship of a polymer.

Structure property relationship of polymers Polymers are known to exhibit wide variety of properties.

Largely extensible under the influence of stress Show readily solubility and fusibility Resistant to heat and solvent

Based on the molecular mass the following relationship. Low molecular mass are soft and gummy

ecular mass are tough and heat resistant By increasing molecular mass the impact strength increases certain e

Melt viscosity initially shows gradual increase then increases steeply with high molecular weight

e properties of polymers such as hardness, permeability, heat capacity etcThe degree of crystallinity of a polymer depends on its structure and its configuration.Polymers made up of linear chains without much bulky groups increases crystallinity. For

mple PE is more crystalline then polystyrene Polymer chains containing polar groups increase crystallinity. For Example nylon 6,6 showing

Higher density, rigidity and strength

E


Well known component of personal Armor such as combat helmets, ballistic face mask and

e, bullet proof vest etc

By increasing molecular mass the impact strength increases certain extent and then become

Melt viscosity initially shows gradual increase then increases steeply with high molecular weight

e properties of polymers such as hardness, permeability, heat capacity etc The degree of crystallinity of a polymer depends on its structure and its configuration. Polymers made up of linear chains without much bulky groups increases crystallinity. For

Polymer chains containing polar groups increase crystallinity. For Example nylon 6,6 showing

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BE II semester

Greater brittleness and heat resistance Lesser solubility and more chemical resistance Lower the permeability to gases and liquids Greater translucent nature

Elasticity Polymer is elongated on applying force and regains original shape on release of force For a polymer to show elasticity the individual chains should not break on prolonged stretching Breaking takes place when chain slips past each other and gets separated For example repeated stretching leads to develops more crystallinity In elastic materials such as rubber property is achieved by1. Introducing cross linking at suitable molecular positions.2. Avoiding bulky side groups 3. Introducing more non polar groups4. Structure should be more amorphous so that material has lower glass transition temperature

which it is used Chemical Resistance

Chemical resistance of a polymer depends on the chemical nature of monomeric units and their molecular arrangement.

Often the chemical attack causes Softening Loss of strength of the polymer material Presence of polar/non polar /Unsaturated groups Degree of crystallinity and molecular mass Degree of cross linking

10 a Discuss the construction, electrode reactions and working principle of Ag/AgCl electrode.Answer: Silver-Silver chloride Electrode

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and heat resistance Lesser solubility and more chemical resistance Lower the permeability to gases and liquids Greater translucent nature

Polymer is elongated on applying force and regains original shape on release of forceto show elasticity the individual chains should not break on prolonged stretching

Breaking takes place when chain slips past each other and gets separated For example repeated stretching leads to develops more crystallinity

rials such as rubber property is achieved by Introducing cross linking at suitable molecular positions. Avoiding bulky side groups Introducing more non polar groups Structure should be more amorphous so that material has lower glass transition temperature

Chemical resistance of a polymer depends on the chemical nature of monomeric units and their molecular arrangement. Often the chemical attack causes

Loss of strength of the polymer material olar/non polar /Unsaturated groups

Degree of crystallinity and molecular mass Degree of cross linking

Discuss the construction, electrode reactions and working principle of Ag/AgCl electrode.

Silver chloride Electrode

E


Polymer is elongated on applying force and regains original shape on release of force to show elasticity the individual chains should not break on prolonged stretching

Breaking takes place when chain slips past each other and gets separated For example repeated stretching leads to develops more crystallinity

Structure should be more amorphous so that material has lower glass transition temperature at

Chemical resistance of a polymer depends on the chemical nature of monomeric units and

Discuss the construction, electrode reactions and working principle of Ag/AgCl electrode.

6

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Department of

BE II semester

Construction The electrode vessel is fitted with a silver wire coated with a fine deposit of AgCl which is

dipped into a solution containing 1M KCl

A crystal of KCl fixed to the Agar bulb is placed at the bottom of the electrode

The reduction potential of Ag

Electrode reactions:

• It behaves both as cathode and anode

Applications • As a secondary reference electrode.

In determining whether the potential distribution is uniform or not in ship hulls and old pipe lines protected by cathodic protection

b Calculate the Mn and Mwof the following

CH2

CH3

COOCH3

C

200 ,

CH2

CH3

COOCH3

C

300

Answer:

1 P E



The electrode vessel is fitted with a silver wire coated with a fine deposit of AgCl which is

dipped into a solution containing 1M KCl


The reduction potential of Ag- AgCl electrode is found to be + 0.222v.

It behaves both as cathode and anode.

As a secondary reference electrode. In determining whether the potential distribution is uniform or not in ship hulls and old pipe lines

d by cathodic protection of the following polymer composition

300 ,

CH2

CH3

COOCH3

C

350 given at wt of O = 16, C = 12, H = 1.

భெభାమெమାయெయ

భାమାయ

E


The electrode vessel is fitted with a silver wire coated with a fine deposit of AgCl which is


electrode is found to be + 0.222v.

In determining whether the potential distribution is uniform or not in ship hulls and old pipe lines

given at wt of O = 16, C = 12, H = 1.

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Department of

BE II semester

ௐ

1 P E



ௐଵ ଵ

ଶଵ ଶ ଶ

ଶଷ ଷ

ଶ

ଵ ଵ ଶ ଶ ଷ ଷ

ௐ

E


ଷଶ

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