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N.P.R. COLLEGE OF ENGINEERING AND

TECHNOLOGY

DEPARTMENT OF CHEMISTRY

ENOTES

Subject Name : ENGINEERING CHEMISTRY I

Subject Code : 10ACH01

Year : I Year (Common to all branches)

Semester : I


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10ACH01 ENGINEERING CHEMISTRY

UNIT I WATER TECHNOLOGY

Water Types Alkalinity types of alkalinity and determination

hardness types CaCO3 equivalents Estimation by EDTA method(problems)Boiler feed waterrequirementsDisadvantages of using

hard water in boiler Internal conditioning(Phosphate, Carbon and

Carbonate)External conditioningZeolite processDemineralization

processDesalinationReverse Osmosis (Chlorination, UV

treatment, ozonation).

UNIT II POLYMERS AND COMPOSITES

PolymersTypesPolymerizationAddition and condensation

polymerizationFree

radical polymerization mechanismPlasticsclassification-

preparation, properties and

uses of PVC, Teflon, Polyurethane, Nylon 6:6, PET, Bakelite, and

Epoxy resin

Compounding of Plastics- Compression mouldingInjection moulding

Composites

definitiontypes of Polymer matrix compositesFRP only.

UNIT III SURFACE CHEMISTRY

AdsorptionTypesAdsorption of gases on solidsAdsorption

isothermsFreundlich

and Langmuir isothermsAdsorption of solids from solutionRole of

adsorption in

catalysis - Ion exchange adsorptionPollution abatement.

UNIT IV NON CONVENTIONAL ENERGY SOURCES AND

STORAGE DEVICES


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Nuclear energyfission and fusion reactionsLight water nuclear

reactor for power

generation (Block diagram only)Breeder reactorSolar energy

conversionSolarcellsWind energyFuel cellsHydrogenOxygen fuel cell

BatteriesAlkaline

batteriesLead acid storage batteryNickelCadmium and Lithium

batteries.

UNIT V ENGINEERING MATERIALS

RefractoriesClassification-( acidic, basic and neutral)Properties

(refractoriness,

refractoriness under load, porosity, dimensional stability, thermal

spalling)manufacture

of alumina, magnesite and Zirconia bricksAbrasivesNatural

abrasives(Quartz,

corundum, emery, garnet, diamond)Artificial abrasives (silicon

carbide, boron carbide)

Lubricants- Mechanism of lubricationLiquid lubricantsProperties

(Viscosity,

viscosity index, flash and fire points, cloud and pour points, oilness ,

aniline number)

solid lubricants (graphite & molybdenum disulphide).

TEXT BOOKS:

1. Engineering Chemistry, P.C.Jain and Monica Jain, Dhanpat Rai

Pub, Co.,New Delhi (2002).

2. A text book of engineering chemistry, S.S. Dara S.Chand &

Co.Ltd.,

New Delhi (2006).


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REFERENCES:

1. Engineering chemistry, B.K.Sharma Krishna Prakasan Media (P)

Ltd.,

Meerut (2001).2. Engineering Chemistry, B. Sivasankar ,Tate McGraw-Hill

Pub.Co.Ltd,

New Delhi (2008).


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UNIT I WATER TECHNOLOGY

Water Types Alkalinity types of alkalinity and determination

hardness types CaCO3 equivalents Estimation by EDTA method

(problems)Boiler feed waterrequirementsDisadvantages of usinghard water in boiler Internal conditioning(Phosphate, Carbon and

Carbonate)External conditioningZeolite processDemineralization

processDesalinationReverse Osmosis (Chlorination, UV

treatment, ozonation).


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Unit-1 Water Technology

The process of removing all types of impurities from water of

impurities from water and making fit for domestic (or)industrial

purpose is called water technology.

Types of impurities in water:

The impurities present in water may be broadly classified into three

types

(i)Physical impurities

(a)Suspended impurities(b) Colloidal impurities

(ii) Chemical impurities

(a)Dissolved salts

(b)Dissolved gases

(iii) Bacterial impurities

Boiler feed water

The water fed into the boiler for the production of steam is called boiler

feed water.

Requirements

Boiler feed water should be free from turbidity, oil, dissolved gases,

alkali and hardness causing substances.

Hard water:

Which does not produce lather with soap soln,but produce white

ppt(scum) is called hard watetr.

2C17H35COONa +Ca++

(C17H35COO)2Ca + 2Na+

Soft water:


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Which produce lather readily with soap soln is called soft water.

Absence of Ca&Mg salts.

Types of hardness:

1.Temporary hardness

2.permanent hardness

Units of hardnss:

Parts per million(ppm)

It is defined as the no.of parts of CaCo3 eqivalent hardness per10

6parts of water.

Milligram per litre(mg/lit)

It is defined as the no.of milligrams of CaCO3 equivalent

hardness per 1 litre of water.

Clarkes degree( Cl)

It is defined as the no.of parts of CaCO3 equivalent hardness

per 105

parts of water.

French degree( Fr)

It is defined as the no.of parts of CaCO3 equivalent hardness per

105

part of water.

1ppm=1mg/lit=0.10Fr=0.070cl

Alkalinity determination:


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PRINCIPLE

Alkalinity in water is due to the presence of soluble hydroxides,

bicarbonates and carbonates. Alkalinity can be determined by

Potentiometric methods

Using pH meter

Titrimetry using different indicators

Determination of various types and amounts of alkalinity is easily

carried out by titration with standard HCl employing the indicators

phenolphthalein and methyl orange independently or in succession.

The following reactions occur when different types of alkalinity are

neutralized with acid.

OH- + H+ H2O completed at pH 8.2-9.0 ----------- (1)

CO32- + H+ HCO3- -------------- (2)

HCO3-

+ H+ (H2CO3) H2O + CO2 , completed at pH

4.2-5.5---(3)

Neutralisation (1) & (2) will be notified by phenolphthalein end-

point while all the three will be accounted by methyl orange end-

point. Bicarbonate in eqn (3) may be due to the existence of soluble

free bicarbonate salts or bicarbonates resulting from half


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neutralization of soluble carbonates (eqn. (2))Various steps to be

followed:

A known volume of water sample is titrated against std. HCl using first

phenolphthalein indicator till end-point (P) and the titration is

continued without break using methyl orange indicator till the

equivalence end-point (M).

From the magnitudes of the P & M, the nature of alkalinity can be

arrived as follows:

(i) P = M => Presence of only OH-

(ii) 2P = M => Presence of only CO32-

(iii) P =0, M#0 => Presence of only HCO3-

(iv) 2P > M => Presence of OH- & CO32-

(v) 2P < M => Presence of HCO3-& CO3

2-

(Mixture of OH- & HCO3-are not listed since they do not exist

together and are considered equivalent to CO32-

).

PROCEDURE


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TITRATION I

STANDARDISATION OF HCl

Exactly 20 ml of the given standard NaOH solution is pipetted out intoa clean conical flask and 2 drops of phenolphthalein indicator is added.

The solution is titrated against the given HCl taken in the burette. The

pink colour of the solution in the conical flask disappears at the end-

point. The titre value is noted down from the burette and the titration

is repeated to get concordant value.

TITRATION II

ESTIMATION OF ALKALINITY IN WATER SAMPLE

Exactly 20 ml of water sample is pipetted out into a clean conical

flask. Few drops of phenolphthalein indicator are added and titrated

against the standardized HCl taken in the burette. The end-point is the

disappearance of pink colour, which is noted as P. Into the same

solution few drops of methyl orange indicator is added. The solution

changes to yellow. The titration is continued further by adding same

HCl without break till the end-point is reached. The end point is the

colour change from yellow to reddish orange. The titre value is noted

as M.

The experiment is repeated to get concordant values. From the

magnitudes of P & M values, the type of alkalinity present in the

water sample is inferred and the individual amounts are calculated

and reported.


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Estimation of hardness by EDTA method:

EDTA:ethylene diammine tetra acetic acid

(CH2COOH )2N-CH2-CH2-N(CH2COOH)2

Principle:

Hadness causing ions (Ca2+,mg2+)estimatimated by titrating the

water sample against EDTA.

Indicator: eriochromeblackT

Buffer soln: (NH4Cl-NH4OH):PH:8-10


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*Ca2,Mg2+EBT*Ca,Mg EBT+ complex(wine red

coloured weak complex)

*Ca ,Mg EBT+Complex EDTA*Ca Mg EDTD+EBT(Steel

blue)

The estimation is based on the complexometric titration.

(i) Total hardness of water is estimated by titrating it

against EDTA using EBT indicator.

EBT+Mn+[EBT-M] (complex)

EBT-M (unstable complex) +EDTA [EDTA-M] (stable complex)

+EBT

(Wine red) (Steel blue)

EBT indicator forms wine red coloured complex with hardness

causing metal ions present in water. On addition of EDTA, metal ions

preferably form complexes with EDTA and steel blue EBT indicator

is set free. Therefore change of colour from wine red to steel blue

denotes the end point.

(iii) Temporary hardness is removed by boiling the water.


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Ca (HCO3)2 CaCO3CO2 +H2O

Mg (HCO3)2Mg(OH)2 2CO2

The precipitate is filtered and the remaining permanent

hardness is estimated using EDTA.

Pipette out 20ml of standard CaCl2 into a 250ml conical flask.

(Standard hard water is prepared by dissolving 1 g of calcium

carbonate in one litre of distilled water) . Add 5ml of buffer solution

and 3 drops of eriochrome black T indictor. Titrate the solution with

EDTA from the burette until the colour changes from wine red to

steel blue at the end point. Repeat the titration for concordant

values. Let the titre value be V1ml.

TITRATION II

(ii) DETERMINATION OF TOTAL HARDNESS

Pipette out 20ml of sample hard water into a clean conical flask.

Add 5ml of buffer solution and 4 -5 drop of eriochrome black T

indicator. Titrate the wine red coloured solution with EDTA from the


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burette until the colour steel blue appears at the end point. Repeat

the titration for concordant values. Let the titre value be V2ml.

TITRATION III

(iii)DETERMINATIONOF PERMANENT HARDNESS

Take 250ml of hard water sample in a 250ml beaker and boil gently

for about 20 minutes. Cool, filter it into a 250ml standard flask and

make the volume upto the mark. Take 20ml of this solution and

proceed it in the same way as in titration (I). The volume of EDTA

consumed corresponds to the permanent hardness of the water

sample. Let the titre value be V3ml. Temporary hardness is

calculated by subtracting permanent hardness from total hardness.

Step 1- Arriving at standard equation,

1ml of Std CaCl 2 = 1 mg of CaCO3 ( given)

V1 ml of EDTA = 20 ml of Std. CaCl 2

1 ml of EDTA = (20 / V1) ml of Std. CaCl 2


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Therefore, ml of EDTA = (20 / V1) mg of CaCO3 (standard

equation.)

Step 2.- Calculation of total hardness.

Volume of EDTA consumed (V2) =-------- ml

20ml of sample hard water = V2 ml of EDTA

1000 ml of sample hard water =V2X(1000/20) ml of EDTA

As per standard equation,100ml of given hard water

= V2 X (1000/20) X (20 / V1) mg of CaCO3

=1000 x (V2 / V1 ) mg of CaCO3

Therefore, total hardness = ----------ppm


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Step 3.- Calculation of permanent hardness.

Volume of EDTA consumed (V3) =-------- ml

20ml of boiled water = V3 ml of EDTA

1000 ml of boiled water =V3 X (1000/20) ml of EDTA

As per standard equation,

1000ml of given hard water= V3 X (1000/20) X (20

/V1) mg of CaCO3

= 1000 x (V3 / V1 ) mg of CaCO3

Therefore, permanent hardness = ----------ppm

Step 4 Calculation of temporary hardness


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Temporary hardness of the given sample of water = Total hardness

Permanent hardness

=ppm

Treatment of water for domestic supply :

Screening:

It is a process of removing the fioating material like

leaves,woodpieces,etc.from water.

Aeration:

The process of mixing water with air is known as aeration.

To remove gases like CO2,H2S


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Sedimentation:

It is a process of removing suspended impurities by allowingthe water to stand un disturbed for 2-6 hours in a big tank.

Coagulation:

In this method certain chemicals called coagulats,like alum,

Al2(SO4)3+6H2OAl(OH)33H2SO4

Filtration :

It is the process of removing

bacteria,colour,taste,odour.passing water through filter beds.

Sterilization(or)disinfection:

The process of destroying the harmful bacteria is known assterilization.

By boiling:


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Water boiled for 10-15minitues all the harmful bacteria are

killed and the water becomes safe for use.

By ozonation

O3O2+[O]

Ozone is a powerful disinfectant and is readily absorbed by water,

By using UV radiation

Using for sterlisizing water in swimming pool.

Cl2+H2OHClHOCl

Cl2+NH3ClNH2+HCl

ClNH2+H2OHOClNH3

CaOCl2+H2OCa(OH)2+Cl2

Cl2+H2OHClHOCl

HOClBacteriabacterias are killed

Break point chlorination:

Water contains following impurities:

1.bacterias

2.organic impurities

3.redusing substances(Fe2+,H2S etc)


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4.Free ammonia

Boiler feed water:

The water feed into the boiler fo the production of steam is calledboiler feed water

Boiler troubles: 1.scale&sludge formation

2.priming&foaming

3.caustic embrittlement

4.boiler corrosion

Sludge: if the ppt is loose and slimy it is called sludge .sludge are

formed by substances like mgcl2,mgso4,cacl2

Scale: if the ppt forms hard&adherent coating on the inner walls of

the boiler like Mg(OH)2,caso4

S.NO sludge scale

1 sludge is a loose ,slimy and non

adherent precipitate.

scale is a hard,adherent coating.

2 The main sludge forming

substance are MgCO3,CaCl2 etc.

The main scale forming substances

areca(HCO3)2,Mg(OH)2


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3 Disadvantages:sludge are poor

conductors of heat.excess of

sludge formation decreases the

efficiency of boiler.

Disadvantages: scales act as a thermal

insulators.it decreases the efficiency of

the boiler.

4 sludge formation can be

prevented by using softened

water.

Sludge can also be removed by

using blow down operation.

scale formation can be prevented by

dissolving using acids like HCl,H2SO4

scale formation can also be removed by

external,internal treatment.

Priming&foaming:

Priming is the process of production of wet steam .priming is casued by

1.high steam velocity

2.very poor boiler design .


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Foaming (the formation of stable bubbles above the surface of

water is called foaming.

Foaming is caused by presence of oil.&grease.presence of finely

divided particle.

Caustic embrittlement:

It means intercrystaline cracking .boiler water containsNa2co3

Na2co3+H2O2NaOHCO2

Fe2NaOHNa2Feo2+H2

Boiler corrosion:

Corrosion in boilers is due to the presence of

1.Dissolved o2

2.Dissolved CO2

3.Dissolved salts

4Fe+6H2O+3O24Fe(OH)3

2Na2SO3+O22Na2SO4

N2H4+O2N2+2H2O

Mechanical de-aeration method:

The high temperature &low pressure produced inside the tower

dissolved oxygen content of the water.

CO2+H2OH2CO3


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2NH4OH+CO2 (NH4)2CO3+H2O

MgCl2+2H2OMg(OH)2+2HCl

Fe2HClFeCl2+H2

Softening(or)conditioning method:

The process of removing hardness producing salts from

water is known as softening(or)conditioning of water.

This method can be done in 2 methods

1.External conditioning

2.Internal conditioning

External conditioning:

Ion exchange (or)demineralization process.

Cation exchanger:

Resins contains acidic functional groups (COOH,SO3H) cation

exchange resin is presented as RH2

ex: 1.sulphonated coals.

2.sulphonated polystyrene RSO3H

Anion exchanger

Resin contain basic functional groups (NH2,OH)Anion exchange

resin is representated as R(OH)2

RH2+CaCl2RCa2HCl


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RH2+mgso4RmgH2SO4

RHNaClRNaHCl

Regeneration:

RCa2HClRH2+CaCL2

RNaHClRHNaCl

RCl22NaOHR(OH)2+2NaCl

Carbonate conditioning: scale formation can be avoided by adding

Na2CO3 to the boiler water.

CaSO4+Na2CO3CaCO3+Na2SO4

Phosphate conditioning: scale formation can be avoided by adding

sodium phosphate.

3CaSO4+2Na3po4Ca3(po4)2

Trisodiumphospate Na3po4(Weaklyalkaline) used for too acidic water.

Disodium hydrogen phosphate-Na2HPO4(weakly alkaline) used for alka

weakly acdic water.

Sodium dihydrogen phosphate-NaH2PO4(acidic) used for alkaline

water.


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Calogen conditioning

Calogen is sodium hexa meta phosphateNa2[Na4(PO3)6]

2Caso4+Na2[Na4(po3)6+Na2[Ca2(PO3)6]+2Na2SO4

The complex Na2[Na4(po3)6] is soluble in water and ther is no problem

of sludge disposal. So calogen conditioning is better than phosphate

conditioning.

Zeolite process:

Hard water contains Ca2

+&Mg2

+ ions this ions form hard soap(in soluble)with soap which does not produce lather with soap soln.

Hard water is softened by passing it through a column packed with

sodium cation exchange resin (called sodium zeolite )


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Na2Ze+Ca2CaZe2Na

Synthetic zeolite is represented by Na2Ze. The sodium ions which are

loosely held in Na2Ze are replaced by Ca2+

and Mg2+

ions present in the

water.

Process:

Sodium ions with Ca2+

and Mg2+

ions present in the water to form Ca

and Mg ions present in the water.

Ca(HCO3)+Na2Ze CaZe2NaHCO3

Mg (HCO3)+Na2Ze MgZe2NaHCO3

CaSO4+ Na2Ze CaZeNa2SO4


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Mg SO4+ Na2Ze Mg ZeNa2SO4

CaCl2 +Na2Ze CaZe2NaCl

Mg Cl2 +Na2Ze Mg Ze+2NaCl

Regeneration:

CaZe+2Na+Cl

-Na2Ze+CaCi2

Desalination of brackish water:

The process of removing common salt from the water is

known as desalination.

1.Fresh water -1000ppm but 35000ppm of dissolved solids.

Reverse osmosis(RO)

Two solns of different concentrations are separated by a semi

permeable membarane.

Flows from a region of lower concentration to higher concentration.

This process is called osmosis .


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Solvent flows from higher concentration to lower

concentration.this is called reverse osmosis.

Advantages:

1.The life of the membarane is high ,and it can be replaced with in

few minutes.

2.It removes ionic as well as nonionic ,colloidal impurities

3.Due to low capital cost,simplicity.


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Unit-I

Part A

1. Define hardness of water.

2. What are the salts responsible for carbonate and non-carbonate hardness of

water?

3. What is meant by soft water and hard water?

4. Distinguish hard and soft water.

5. How the hardness of water is expressed?

6. Give the significance of calcium carbonate equivalent.

7. How does EBT indicator function as an indicator in EDTA titration?

8. What is meant by permanent hardness of water?

9. Define alkalinity?

10. How is alkalinity classified?

11. How is alkalinity determined?

12. Why water is softened before using in boilers?

13. What are scales and sludges?

14. What is meant by priming and foaming?

15. How the caustic embrittlement is prevented?

16. Indicate the reasons for boiler corrosions.

17. Define softening of water. How it is carried out?

18. Soft water is demineralised water (DM) where as DM water is a soft water.Justify.

19. What is sodium Zeolite?

20 (a). What is aeration of water/Mention its uses?

(b). What is calgon conditioning?


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(c). Explain the term break point chlorination.

(d). What is desalination?

(e). What is blow down operation?.

(f). How hardness of water is removed in zeolite process?

Part-B

1. Describe the principle and method involved in the determination of different

types and amount of alkalinity of water.

2. Explain the EDTA method of estimation of hardness of water.

3. What are boiler troubles? How are they caused? Suggest steps to minimize the

boiler troubles.

4. What is potable water? What are the steps taken to obtain pure drinking

water?

5. How is internal treatment of boiler water carried out?

6. What is desalination? Name the different methods of desalination. Explain the

reverse osmosis in detail.

7. Discuss the chlorination, ozonation and UV methods of disinfection.

8. Explain Zeolite process in detail.

9. Explain the process of sterilization of domestic water supply?

10.(a) 100ml of a water sample requires 20ml of EDTA solution for titration. 1ml

of EDTA solution is equivalent to 1.1mgs of CaCO3. Calculate the hardness in ppm.

(b).In an estimation of hardness of water by EDTA titration 250 ml of a sample

water require 15ml of 0.025M EDTA solution to get the end point. Calculate the

hardness of water.


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UNIT II POLYMERS AND COMPOSITES

PolymersTypesPolymerizationAddition and condensation

polymerizationFree

radical polymerization mechanismPlasticsclassification-preparation, properties and

uses of PVC, Teflon, Polyurethane, Nylon 6:6, PET, Bakelite, and

Epoxy resin

Compounding of Plastics- Compression mouldingInjection moulding

Composites

definitiontypes of Polymer matrix compositesFRP only.


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Unit-2

POLYMER

Polymer: polymers is macromolecules formed by the repeated

linking of large no.of small molecules called monomers.

Monomers:

nCH2=CH2 (-CH2-CH2-) n

Ethylene Polyethylene

Monomer:

Monomer is a micromolecule which combines with each other to

form a polymer.

EX:

CH2=CH2(Monomer) -CH2-CH2- (repeating unit)

Polymerization

Polymerization is a process in which large no.of small molecules

combine to form a big molecule with (or)with out elimination of small

molecules like water.

Degree of polymerization:

The no .of repeating unit in a polymer chain is known as degree

of polymerization.

3CH2=CH2-CH2-CH2-CH2-CH2-CH2-CH2-


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Tacticity:

The orientation of monomeric units(or)functional groups in

polymer molecule can take place in a orderly (or)disorderly manner

with respect to the main chain is known as tacticity.

Functionality:

The no.of bonding sites (or)functional groups present in a

monomer is known as its functionality.

1.bifunctional monomer

2.Trifunctional monomer

3.polyfunctional monomer

Ex:poly ethylene,poly propy lene

..-M-M-M-M-M-M-M-M-M-M-M.

Copolymer (Heteropolymer) :

A polymer containing more than one type of monomer is known

as copolymer.

Ex: nylon ,terylene.

-M1-M2-M1-M2-M1-M2-M1

Hetero chain polymer:

If the main chain of a polymer is made up of different

atoms.

Ex: nylon 6:6 . ...C-C-O-C-C-O -C-C


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Addition(or)chain growth polymerization :

It is a reaction that yields a polymer ,which is an exact multiple of

the original monomeric molecule contains one(or)more double

bond.in addition polymerization there is no elimination of any

molecule.

Ex:polyethylene is produced from ethylene

nCH2=CH2 n.CH2-CH2.-(CH 2-CH2-)n

ethylene polyethylene

Ex: pvc is produced from vinyl chloride

nCH2=CH-Cl - nCH2- CH . (-CH2-CH-Cl)n

vinyl chlori de | PVC

cl

Bifunctional monomer

EX: PAN is produced from acrylonitrile

nCH2=CH-CN . CH2-CH - .. (CH2-CH-CN-)n

|

CN

Acrylonitrile Bifunctional monomer PAN

Condensation polymerization


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It is a reaction between simple polar groups containing

monomer with the formation of polymer and elimination of small

molecule like H2O

Hexamethylene diamine react with adipic acid condense to form of

nylon6:6

nH2N(CH2)6NH2 +n HOOC(CH2)4 -COOH -[HN-

(CH2)6NHCOCH2- CO -]n(Nylon 6:6)

copolymerization:

it is the joint polymerization in which 2(or) more differentmonomers combine to give a polymer.

nCH2=CHCH =CH2 +n CH2= CH -(CH2-CH=-CH-CH2-CH2-CH-)

| |

C6H5 C6H5

Butadiene styrene polybutadiene co

styrene

Plastics

Plastics are high molecular organic material that can be moulded

into any desired shape by the application of heat and pressure in the

presence in the presence of a catalysit.

Classification of plastics:

1.Thermopiastics ex:pvc, polyethylene


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2.Thermosetting plastics ex:Bakelite, polyester

Thermoplastic resin:

Thermoplastic can be softened on heating and hardened oncooling. They are generally soluble in organic solvent.

Ex: pvc, polyethylene

Thermosetting resin

Theremosetting plastics are prepared by condensation

polymerization.this plastics get harden on heating and once harden

cannot be softened again.

Ex;Bakelite,polyester.

s.no Thermoplastic resins Thermosetting resins

1 They are formed by addition

polymerization

They are formed by

condensation polymerization.

2 The cnsist of linear long

chain polymer.

They consist of three

dimentional network structure.

3 They are weak,softand less

brittle.

They can be remoulded

They are strong,hard and more

brittle.

They can not be remoulded.

4 They soften on heating and

harden on cooling.

They do not soften on heating.


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Engineering plastics :

Engineering plastics are a group of materials obtained from high

polymer resins ,they posses high mechanical strength,toughness.

Ex:pvc,Teflon,PET,Nylon 6:6

Preparation of pvc:. Pvc obtained by heating water emulsion of vinyl

chloride in the presence of benzoyl peroxide.

nCH2 =CHCl ( -CH2-CH-) catalyst:H2O2

|

Cl

Vinylchloride polyvinylchloride

properties: PVC is chemically inert powder. Insoluble in acids and

alkalies and undergoes degradation in presence of light.

Uses:

1. It is used in the production of pipes,cable insulator,table

cover,rain coat etc.

2. It is also used for making sheets,light fittings etc.

Teflon:

Teflon obtained by polymerization of water emulsion of

tetrafluoroethylene in presence of benzoyl peroxide under pressure.Tough, high softening point (350

0C), very high chemical inertness and

thermal stability


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( C6H5CO)2O2

n CF2=CF2 ( -CF2-CF2-) n

Tetrafluroethylene Teflon

Properties:

Teflon is extremely tough,flexible materials possing high softening

point.

It possees extremely good electrical and mechanical properties

Uses:

1.it is used as a very good electrical insulating material in

motors,cables.

2.it is also used for making gaskets ,packing,pump pa rts.

3.it is used in making non sticking stop cocks for burettes.

Perlon-U:

It is obtained by the reaction of 1,4,butanediol with

1,6hexamethylene di- isocyanate

O=C=N-(CH2)-N=C=O + HO-(CH2)4-OH

1,6Hexamethylene di-isocyanate 1,4butane diol

polymerisation

n [-O=C-HN-(CH2)6-NH-COO-(CH2)4-OH ]

( perlon-U)

Properties:


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It is less stable than polyamide.

It is easily affected by moisture.

It is characterized by excellent resistance to abrasion and solvents.

Uses:

1.perlonU Is used as coatings,films foams,adhesives&elastomer.

2.They are aiso used in defence,oceanographic research.

3.The are aiso used in foundation garments &swim suits.

Nylon 6:6

Nylon 6:6 is obtained by the polymerization of adipic acid &hexa

methylenediamine

n H2N-(CH2)-NH2 + nHOOC-(CH2)4-COOH

[-HN-(CH2)6-NHCO-(CH2)4-CO-]n

Nylon6:6

Properties:

Nylons are translucent, whitest,horny andhigh melting polymers.

They are insoluble in common organic solvents and soluble in phenol

and formic acid.

Uses:

1.Nylon 6:6 are used for making filaments for ropes ,bristles for

tooth b rushes etc.


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2.Nylon 6:6 is used for fibres,which is used in making

socks,carpets.etc

PET(poly ethylene terephalate)

Preparation

It is a saturated polyester,prepared by condensation of ethylene

glycol and terephthalic acid.

Properties

It is a good fibre forming material and is converted into commercialfibres.

The fibres posses high stretch resistance ,highcrease and wrinkle

resistance.

Uses

It is mostly used for making synthetic fibres like terylene.etc.

It is used for blending with wool,to provide better crease and wrinkle

resistance.


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Bakelite

It is obtained by the condensation polymerization of phenol and

formaldehyde in the presence of acid (or)alkali catalyst.

Step 1

Methylolation

The first step is the reaction between phenol and

formaldehyde,forms mono,di and tri methylol phenols.

Stepii

Formation of A stage resin (resole)

Resole is a low molecular weight linear polymer.


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Formation of Bstage resin(novolac(or)resitol

Novolac is high molecular weight linear polymer.

Production of C stage resin(Bakelite)

Further heating of A stage resin (or)B stage resin (or) both in the

presence of a curing agent produces hard ,rigd ,crosslinked

polymer called Bakelite.

Properties

Bakelite is resistant to acids ,salts and most organic solvent,but it

is attacked by alkalis because of the presence ofOH groups.

Uses


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Bakelite is used as an adhesive in plywood lamination and in grinding

wheelsw ,etc.

It is also widely used in paints,varnishes.

Epoxide (epoxy resins

Preparation

Epoxy resins are important thermosetting synthetic resins. They are

polyethers ,prepared by the condensation of epichlorohydrin with

bisphenol-A

Properties

Epoxy resin adhesives are thermosetting resins and posses good

adhesives properties.

They have good chemical and electrical resistance.

Uses

Epoxy resins are used to bind number of substances including metals

and glasses.

Epoxy resin adhesives are sold in the market as in the name of

araldite.


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.

Compounding of plastics:

Compounding of plastics is a process by which polymer resi

ns are mixed with some additives like fillers ,plasticizers etc .


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Fabrication of plastics :

Fabrication involves conversion of polymeric materials into

desired shape.many methods are employed for the fabrication

which depants on the types of plastics.

Moulding process:

The process involes fabrication of plastics materials into desired

shape under the influence of heat and pressure in


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theclosedchamber1.compression moulding

This method applied to both thermoplastics and thermosetting

plastics.this method mould is made up of two halves .the material to

be mouleded is placed in the cavity care fully under low pressure.

Finally the moulded is heated to 100-2000

C. after curing the

moulded article is taken out by opening the mould parts.

Injection moulding:


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This method is mainly applicable to thermoplastic .the powdered

plastic material is fed into the heated cylinder through the hopper .the

plastic material melts under the influence of heat and becomes fluid.

The mould is kept cold to allow the hot plasic to cure and

becomes rigd.telephone,buckets etc. are made by this method.

COMPOSTIES AND FRP

The most primitive composite materials were straw and mud combined

to form bricks for building construction; the Biblical Book of Exodus

speaks of the Israelites being oppressed by Pharaoh, by being forced to

make bricks without straw being provided. The ancient brick-making

process can still be seen on Egyptian tomb paintings in the Metropolitan

Museum of Art. The most advanced examples perform routinely on

spacecraft in demanding environments. The most visible applications

pave our roadways in the form of either steel and aggregate reinforced

portland cement or asphalt concrete. Those composites closest to our

personal hygiene form our shower stalls and bath tubs made of

fiberglass. Solid surface, imitation granite and cultured marble sinks and

counter tops are widely used to enhance our living experiences.

Composites are made up of individual materials referred to as

constituent materials. There are two categories of constituent materials:

matrix and reinforcement. At least one portion of each type is required.

The matrix material surrounds and supports the reinforcement materials

by maintaining their relative positions. The reinforcements impart their

special mechanical and physical properties to enhance the matrix

properties. A synergism produces material properties unavailable fromthe individual constituent materials, while the wide variety of matrix and

strengthening materials allows the designer of the product or structure to

choose an optimum combination. Engineered composite materials must

be formed to shape. The matrix material can be introduced to the

reinforcement before or after the reinforcement material is placed into
http://en.wikipedia.org/wiki/Strawhttp://en.wikipedia.org/wiki/Mudhttp://en.wikipedia.org/wiki/Brickhttp://en.wikipedia.org/wiki/Biblehttp://en.wikipedia.org/wiki/Book_of_Exodushttp://en.wikipedia.org/wiki/Israeliteshttp://en.wikipedia.org/wiki/Pharaohhttp://en.wikipedia.org/wiki/Bricks_without_strawhttp://en.wikipedia.org/wiki/Art_of_Ancient_Egypt#Paintingshttp://en.wikipedia.org/wiki/Metropolitan_Museum_of_Arthttp://en.wikipedia.org/wiki/Metropolitan_Museum_of_Arthttp://en.wikipedia.org/wiki/Portland_cementhttp://en.wikipedia.org/wiki/Asphalt_concretehttp://en.wikipedia.org/wiki/Fiberglasshttp://en.wikipedia.org/wiki/Fiberglasshttp://en.wikipedia.org/wiki/Asphalt_concretehttp://en.wikipedia.org/wiki/Portland_cementhttp://en.wikipedia.org/wiki/Metropolitan_Museum_of_Arthttp://en.wikipedia.org/wiki/Metropolitan_Museum_of_Arthttp://en.wikipedia.org/wiki/Art_of_Ancient_Egypt#Paintingshttp://en.wikipedia.org/wiki/Bricks_without_strawhttp://en.wikipedia.org/wiki/Pharaohhttp://en.wikipedia.org/wiki/Israeliteshttp://en.wikipedia.org/wiki/Book_of_Exodushttp://en.wikipedia.org/wiki/Biblehttp://en.wikipedia.org/wiki/Brickhttp://en.wikipedia.org/wiki/Mudhttp://en.wikipedia.org/wiki/Straw


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the mold cavity or onto the mold surface. The matrix material

experiences a melding event, after which the part shape is essentially set.

Depending upon the nature of the matrix material, this melding event

can occur in various ways such as chemical polymerization or

solidification from the melted state.

. Most commercially produced composites use a polymer matrix

material often called a resin solution. There are many different polymers

available depending upon the starting raw ingredients. There are several

broad categories, each with numerous variations. The most common are

known as polyester, vinyl ester,epoxy,phenolic,polyimide,polyamide,

polypropylene, PEEK, and others. The reinforcement materials are often

fibers but also commonly ground minerals. The various methodsdescribed below have been developed to reduce the resin content of the

final product, or the fibre content is increased. As a rule of thumb, lay up

results in a product containing 60% resin and 40% fibre, whereas

vacuum infusion gives a final product with 40% resin and 60% fibre

content. The strength of the product is greatly dependent on this ratio.

Fibre-reinforced plastic (FRP) (also fibre-reinforced polymer) are

composite materials made of a polymer matrix reinforced with fibres.

The fibers are usually fiberglass, carbon, or aramid, while the polymer isusually an epoxy, vinylester or polyester thermosetting plastic. FRPs are

commonly used in the aerospace, automotive, marine, and construction

industries.

Examples of polymers best suited for the process

Reinforcing

Material

Most Common Matrix

MaterialsProperties Improved

Glass FibersUP, EP, PA, PC, POM,

PP, PBT, VE

Strength, Elastic, heat

resistance
http://en.wikipedia.org/wiki/Polyesterhttp://en.wikipedia.org/wiki/Vinyl_esterhttp://en.wikipedia.org/wiki/Epoxyhttp://en.wikipedia.org/wiki/Phenolichttp://en.wikipedia.org/wiki/Polyimidehttp://en.wikipedia.org/wiki/Polyamidehttp://en.wikipedia.org/wiki/Polypropylenehttp://en.wikipedia.org/wiki/PEEKhttp://en.wikipedia.org/wiki/Composite_materialhttp://en.wikipedia.org/wiki/Polymerhttp://en.wikipedia.org/wiki/Fiberglasshttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Aramidhttp://en.wikipedia.org/wiki/Epoxyhttp://en.wikipedia.org/wiki/Vinylesterhttp://en.wikipedia.org/wiki/Polyesterhttp://en.wikipedia.org/wiki/Thermosetting_plastichttp://en.wikipedia.org/wiki/Thermosetting_plastichttp://en.wikipedia.org/wiki/Polyesterhttp://en.wikipedia.org/wiki/Vinylesterhttp://en.wikipedia.org/wiki/Epoxyhttp://en.wikipedia.org/wiki/Aramidhttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Fiberglasshttp://en.wikipedia.org/wiki/Polymerhttp://en.wikipedia.org/wiki/Composite_materialhttp://en.wikipedia.org/wiki/PEEKhttp://en.wikipedia.org/wiki/Polypropylenehttp://en.wikipedia.org/wiki/Polyamidehttp://en.wikipedia.org/wiki/Polyimidehttp://en.wikipedia.org/wiki/Phenolichttp://en.wikipedia.org/wiki/Epoxyhttp://en.wikipedia.org/wiki/Vinyl_esterhttp://en.wikipedia.org/wiki/Polyester


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Carbon and

Aramid FibersEP, UP, VE, PA Elasticity, Tensile Strength

Inorganic

Particulates

Semicrystalline

Thermoplastics, UP

Isotropic shrinkage,

abrasion, compression

strength


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UNIT II

PART A

1. Define co - polymerization.

2. What are plastics?3. Difference between thermosetting and thermoplastics. (any four)

4. Write notes on Epoxides.

5. Give any two properties of PC, Polyamide.

6. What is elastomer?

7. Define SBR (or) BUNA S. and explain the preparation of the same.

8. Define polymer. Give examples.

9. Define monomer. Give examples.

10.What is dead polymer?

11.What are engineering plastics?12.What is fluon? Mention its uses.

13.What is vulcanization of rubbers?

14.Mention some important uses of SBR.

15.What is the role of fillers in plastics?

16.Draw the structure of Bakelite.

17.What is the function of plasticizers in plastics?

18.Define degree of polymerization.

19.Define oligomers and high polymers.

20.How PVC is prepared?

PART B

1. Differences between addition and condensation polymerization?

2.Discuss the mechanism of addition (free radical) polymerization.

3.Write notes on vulcanization of rubber.

4. What is compounding of plastics? Give the names of various ingredients and

their function.5.Discuss the injunction moulding process with neat sketch.

Describe the preparation properties and uses of Bakelite.

6.How do you prepare the following polymers

Teflon 2) Nylon 6, 6 3) Polystyrene 4) Polyurethane


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7.Differentiate between thermoplastic and thermosetting resins.

8.Preparation, properties and uses of the following synthetic rubbers.

a) Buna S b) Butyl rubber

9.Explain compression moulding of plastics with a neat diagram.


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UNIT III SURFACE CHEMISTRY

AdsorptionTypesAdsorption of gases on solidsAdsorption

isothermsFreundlich

and Langmuir isothermsAdsorption of solids from solutionRole ofadsorption in

catalysis - Ion exchange adsorptionPollution abatement.


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Unit:3

Surface chemistry

Adsorption is the phenomenon of concentration of molecules of agas or liquid at a solid surface.

The adsorption of gas on a solid is sometimes called occlusion.

The substance which is held on the surface of the solid is called the

adsorbate.

The solid that takes up a gas or a solute from the solution is called

the adsorbent.

Absorption implies that a substance is uniformly distributed

throughout the body of the solid or liquid.

Adsorption is the surface phenomenon, but absorption is bulk

phenomenon.

Sorption is the process in which both adsorption and absorption

takes place simultaneously.

Adsorption:

The phenomenon of concentration of molecule of a

gas(or)liquid at a solid surface is called


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adsorpation .

Types of adsorption:

1.physical adsorption

2.chemical adsorption

DIFFERENCES BETWEEN PHYSISORPTION AND CHEMISORPTION

Physisorption chemisorption

It is caused by intermolecularvanderwaals forces(weak) It is caused by chemical bondformation

Heat of adsorption is low(0-

40k.cal/mole.

Heat of adsorption is high(40-

400k.cal/mole.

Adsorption is completely reversible Adsorption is irreversible

Adsorption decreases with increase

in temperature.

Adsorption increases with

temperature.

Multilayer adsorption occurs. Only monolayer adsorption occurs.

Equilibrium is established rapidly. But it requires time.

It is not specific in nature. But it highly specific in nature.


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CHARACTERISTICS OF ADSORPTION

1. spontaneous.

2. Always accompanied by evolution of heat.

3. Accompanied both by decrease in enthalpy and entropy of the

system.

4. Selective process.

5 .The rate of adsorption depends on temperature.

6 .Adsorption is a physical phenomenon, but accompanied by a

chemical change.

7 .It is specific, it depends on the nature of adsorbent and adsorbate.

Physical adsorption:

Physical adsorption is the one,in which the adsorbed molecules

are held on the surface of the adsorbent by the weak physical (or)

vanderwaals force of attraction.

Ex: Adsorption of H2(or)O2 on charcoal.

Chemical adsorption : (or) chemisorptions

Chemical adsorption is the one,in which adsorbed molecules are

held on the surface of adsorbent by chemical bonds(covalent bond

(or)ionic bond)


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Ex: Adsorption of H2 on NI

H2 molecule is first adsorbed by vanderwaals force and then

undergoes dissociation to hydrogen atom .H-atom chemisorbed on NI

Adsorption of gases on solid :

All solids adsorb gases to some measurable extent . The

magnitude of adsorption of gases by solids depand on the

following factors.

1.Naure of gases.

2.Nature and surface area of adsorbents.

3.pressure of gas

4.Temparature of gas

5.Activation of absorbentFactors influencing adsorption of gases on

solids

Nature of gases

Easily liquefiable gases like HCL,NH3 adsorbed more easily than

the permanent gases like H2,O2, etc.,

This is due to (i) Critical temperature (ii) Vander waals foreces.

Nature and surface area of adsorbent

The greater the surface area, larger pores on the adsorbent

larger is the adsorption.eg.Charcoal and Silica gel.


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Heats (or) Enthalpy of adsorption

The energy liberated when 1 gm mole of a gas is adsorbed on

the solid surface. In physical adsorption it is small due to weak vander

waa,s forces, in chemical adsorption it is large due to the formation ofchemical bonds.

Reversible character

It is a reversible process. The gas adsorbed on a solid can be

removes under reverse conditions of temperature and pressure.

Chemical adsorption is not a reversible process, because a

surface compound is formed.

Effect of pressure

Since dynamic equilibrium exists between the adsorbed gas and

the gas in contact with the solid, increases of pressure increases

adsorption and decrease of pressure causes desorption.

Effect of temperature

Physical adsorption:It occurs rapidly at lower temperature and

decreases with increase in temperature.

Chemical adsorption: It increases with increase in temperature

and then decreases.

Vander waals forces:


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Easily liquefiable gases posses greater vander waals forces

than permanent gases

Thickness of adsorbed layer of gas

In physisorption multimolecular thick layer is formed, in

chemisorption one molecule thick layer is formed.

Effect of activation of adsorbent

Activation leads to increase in the surface.

(1)Creation of rough surface

(a) by mechanical rubbing,

(b) by subjecting to some chemical reactions on the solid

adsorbent.

(2)Increasing effective area of the surface

(a) by sub dividing the solid adsorbent into fine particles.(b) by heating of solid adsorbent in superheated steam now

its pores are opened and

adsorption increases.

ADSOPTION OF SOLUTES FROM SOLUTIONS

An adsorbent adsorbs substances(solutes) from the solution in two

ways.


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1.Solid substances adsorb dissolves substances from solutions.

Eg. Activated charcoal adsorbs coloring matter present in sugar

solution.

2.An adsorbent also adsorbs certain substance from the solution in

preference to other substances.

Eg. Charcoal adsorbs non-electrolytes more readily than electrolytes

from a solution.

FACTORS INFLUENCING ADSORPTION OF SOLUTES FROM

SOLUTIONS

1.Effect of temperature and concentration

(a)Negative adsorption

2.Effect of surface areaSurface area of the adsorbent increases, adsorption increases.

3.The nature of the solute adsorbed

The extent of adsorption is usually greater, when the

molecular weight of the solute is high.


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ADSORPTION ISOTHERMS

Definition: Adsorption isotherm is a relationship (or a graph) between

magnitude of adsorption with pressure at constant temperature

FREUNDLICHS ADSORPTION ISOTHERM

The relationship between the magnitude of adsorption (x/m) and

pressure (P) can be expressed mathematically by an empirical equation

known as Freundlich adsorption isotherm.

I.e., x/m = KP1/n


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DERIVATION OF FREUNDLICHS ADSORPTION ISOTHERM

This equation may be derived from the result observed from the above

graph. Thus,

(i) At low pressure: Adsorption increases with pressure

x/m P (or) x/m=KP

(ii)At high pressure: Adsorption is almost constant

x/m = constant (or) x/m = K

(iii)At intermediate (normal) pressure: Adsorption depends on 0 to 1

power of pressure (ie., fraction a power of pressure)

x/m P1/n

(or) x/m = KP1/n .(1)

where, n= whole number.


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(1) This eqn(1)is called Freundlichs adsorption isotherm.

Taking logarithm on both sides, the above equation becomes

log x/m=log K + 1/nlog P

On plotting logx/m Vs logP, a straight line is obtained with a slope of

1/n and intercept log K.

DISADVANTAGES / LIMITATIONS OF FREUNDLICHS

ADSORPTION ISOTHERM

1.Freundlich equation is purely empirical and has no theoretical basis.

2.The equation is valid only upto a certain pressure and invalid at

higher pressure.

3.The constants K and n are not temperature independents, they vary

with temperature.

4.Freundlichs adsorption isotherm fails, when the concentration of

adsorbate is very high.

LANGMUIRS ADSORPTION ISOTHERM

Langmuir derived an equation based on some theoretical

considerations.

The postulates (or) assumptions of langmuir,s theory are


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1.Valencies at the surface of adsorbent are not fully satisfied.

2.The adsorbed gas layer on the solid surface is only one moleculethick.

3.The surface of the solid is homogeneous, so the adsorbed layer is

uniform all over the adsorbent.

4.There is no interaction between the adjacent adsorbed molecules.

5.The adsorbed gas molecules do not move around on the surface.

DERIVATION OF LANGMUIR ISOTHERM

According to Langmuir,s assumptions, when the gas molecules strike

a sold surface, some of the molecules are adsorbed and some of these

are desorbed. Thereby dynamic equilibrium is established betweenadsorption and desorption. If A is gas molecule and M is surface then,

ka

A(g) + M(surface) AM

kd


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Let,

Fraction of the total surface covered by the adsorbed

molecule =

Fraction of uncovered are (vacant area) = (1- )

The rate of desorption is proportional to number of adsorbed

molecules = Rd=kd

where, kd= Rate constant for desorption.

Thus, the rate of adsorption is proportional to available

uncovered area=Ra=ka(1- )P

Where, ka= Rate constant for adsorption.

At euilibrium

Rate of desorption Rate of adsorption


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kd =ka(1- )P

=kaP-ka P

kd +ka P=kaP

(kd+kaP)=kaP

= kaP ------------------------(1)

(kd=kaP)

Dividing the equation (1) by kd, it becomes

= (ka/kd)P

1+ (ka/kd)P

= KP .(2)

1+KP

where, ka/kd=K= equilibrium constant, called adsorption coefficient.

But, the amount of gas adsorbed per gram of the adsorbent, x, is

proportional to


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x (3)

on comparing equation (2) and (3), it becomes

x KP

1+KP

x = K KP (4)

1+KP

where, K = New constant.

The equation (4) gives the relation between the amount of gas

adsorbed to the pressure of the gas at constant temperature is known

as Langmuir Adsorption isotherm.

The above equation (4) may be re-written as

1+KP = KKP

x


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1 + KP = P

KK KK x

1 + K P = P

KK KK x

The equation (5) is similar to an equation for a straight line (ie.,

y=c+mx). If the graph is plotted between p/x Vs P, we should get a

straight line with slope K and the intercept1/kk

This equation is found valid in all cases.

Case (I): At low pressure : If the pressure (P) is very low K P term

is negligible, kk

i.e., 1 K P

KK KK

Hence equation (5) becomes


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1 = P

KK x (or) x = PKK (6)

ie., amount of adsorption per unit weight of adsorbent is directly

proportional to the P at high 1 term is negligible,

KK

K P 1

KK KK

Hence equation (5) becomes

K P = P

KK x (or) x = K (constant)

(or) x = K P0 ..(7)

ie., extent of adsorption is independent of pressure of the gas, because

the surface becomes completely covered at high pressure.


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Case (iii) At normal pressure: At normal (intermediate) pressure the

equation (7) becomes

X=KPn (8)

Where, n lies between 0 and 1.

Equation (8) is Freundlichs adsorption isotherm.


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MERIT AND DEMERIT

Langmuir adsorption isotherm holds good at lower pressure but fails at

high pressure.

APPLICATIONS OF ADSORPTION

1.Activated Charcoal

(a)Gas-Masks - absorb toxic gases.

(b) Remove coloring matter from the sugar solution and the

decoloration in vinegar

2.Silica and alumina gels

These are used as adsorbent for removing moisture and for

controlling humidities of room.

3. Ion exchange resins

Softening of hard water can be done based on the principle of

competing adsorption using ion-

exchange resins.

4. Chromatographic analysis

Selective adsorption by alumina, magnesia, etc., can be used

for separating different pigments and

also mixtures of small quantities of organic substances with the

help of adsorption chromatography.


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4.Measurement of surface area

5.Surface area of powders and rough surfaces can be measured using

adsorption measurements.

ROLE OF ADSORBENT IN CATALYTIC REACTIONS (OR) ADSORPTION

(OR) CONTACTTHEORY

1.Action of heterogeneous catalyst:

Hydrogenation of ethylene using Ni catalyst.

Step :1

Adsorption of reactant molecule

Step:2


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Step:iii Decomposition of activated complex

Step iv: Desorption of product:

Finely divided state of catalyst is more efficient.

.

Free valencies=12

Desorption of products


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The products are desorbed (or) released from the surface. They are

stable.

2.Finely divided state of catalyst is more efficient

Fineness of the catalyst increase, the free surface area gets

increases, thereby free valencies increases.

3.Enhanced activity of a rough surfaced catalyst

It possess Cracks, Peaks, Corners etc., and consequently

have larger number of active centers. These active centers increase the

rate of reaction.

4.Action of promoters

Promoters are defined as the substances, which increase the activity of

a catalyst.


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(i) Promoters change the lattice spacing

(ii) Promoters increase the peaks and cracks

5.Action of catalytic poisons

Catalytic poison is defined as a substance which destroys the activity of

the catalyst to accelerate a reaction.This process is called catalytic

poisoning.

Number of free valencies (or) active centres of catalysts are

reduced by the preferential adsorption of the poison. So rate of

reaction decreases.

6.Specific action of the catalyst


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The adsorption depends on the nature of both the adsorbent

(catalyst) and the adsorbate (reactants). So, different catalysts cannot

possess the same affinity for the same reactants. Thus, the action of

the catalyst is specific.

ACTIVATED CARBON IN POLLUTION ABATEMENT OF AIR AND WASTE

WATER

Activated carbon is the most commonly used adsorbent because it has

a large surface area per unit weight (or) unit volume of solid.

Scope of the study

1.Preparation and properties of activated carbon.

2.Use of granular and powdered activated carbon.

3.Regeneration of activated carbon.

Production of Activated Carbons

Step I: Production of Char

The char is produced by heating the materials like coconut, wood,

coal, petroleum residues to a red heat in a retort to remove the

hydrocarbons but with an insufficient supply of air to sustaincombustion.


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Step II: Activationof Char Particles

The char particles are then activated by exposure to an oxidizing gas

at a high temperature. The gas

Creates a porous structure and large internal surface area in the char

due to the removal of adsorbed hydrocarbons and some of the carbon.

Classification of Activated Carbon

Based on size and different adsorption capacities-two main classes.

1.Granular Activated Carbons(GAC)

These carbons have a diameter of greater than 0.1 mm and are

generally used for the adsorption of gases and vapours.

2.Powdered Activated Carbons(PAC)

These carbons have a diameter of less than 200mesh and are generally

used in purification of liquids.


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Properties of Activated Carbon

The properties of Ac are governed not only by the nature of raw

materials but also by the method of activation used. Property of AC ishighly helpful in specifying the carbon for a specific applications.

Eg.1.Decolorizing activated carbon:

It is usually employed as powders.Generally raw material for this

type have a weak structure.

Eg. Saw dust and lignite yield carbon of this kind.

2.Vapour adsorbent carbon: It is used in the form of hard

granules.

Eg. Coconut shells, fruit pits, briquette coal yield carbon of this kind.

Adsorptive Capacity: It is used to find out the effectiveness of the

carbon in removing desired constituents such as COD, colour,

phenol,etc., from the waste water.

Phenol number: It is used the find out the ability of AC to remove

taste and odour compounds.

Iodine number: It is used to find out the ability of AC to adsorb low-

molecular weight substances.


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TREATMENT OF POLLUTED WATER AND AIR

1.Using Granular Activated Carbon (GAC)

A fixed bed column is often used for contacting polluted water or air

with GAC.It can be operated singly, in series or in parallel.Among the

various type two are important.

1.Down flow carbon contactors.

2.Upflow carbon contactors.

(A) Down flow Carbon Contactors

It usually consist of two (or) three columns operated in series (or) in

parallel.

The water or air is applied to the top of the column and withdrawn

at the bottom. The AC is held in place with an under drain system at the

bottom of the column. Provision for back washing and surface washing


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is usually necessary to limit the headless build up due to the removal of

particle material with the carbon column.

Advantage

Adsorption of organic materials and filtration of suspended solids are

accompanied in a single step.

Disadvantages

Down flow filters may require more frequent back washing because

of the accumulation of suspended materials on the surface of the

contactor.

Plugging of carbon pores may require premature removal of the

carbon for regeneration, thereby decreasing the useful life of the

carbon.

(b)Upflow Carbon Contactors

In the upflow columns, the polluted water or air moves upward from

the base of the column .


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Advantage:

As the carbon adsorbs organic materials, the apparent density of

the carbon particles increases and encourages migration of the heavier

or spent carbon downward.

Disadvantage

upflow columns may have more carbon fines in the effluent than

downflow columns, because upflow tends to expand, not compress, the

carbon.

Bed expansion allows the fines to escape through passage ways

created by the expanded bed.


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2.Using Powdered Activated Carbon (PAC)

In this method PAC is added directly to the effluent coming out from

the various biological treatment processes. In the case of biological-treatment plant effluent, PAC is added to the effluent in a contacting

basin. After some time, the carbon is allowed to settle at the bottom of

the tank, and the treated water is then removed from the tank.

Since carbon is very fine, a coagulant such as polyelectrolyte may be

added to aid the removal of the carbon particles or filtration throughgranular medium filters may be required.


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Regeneration of Activated Carbon

Thermal methods are widely and effectively used.

(i)Granular carbon It can be regenerated easily in a furnace by heatingin the presence of limited amount of water vapour, flue gas and

oxygen. Some of the carbon (5 to 10%) is destroyed in the regeneration

process and must be replaced with new carbon.

(ii) Powdered carbon

This methodology is not well-defined. The use of powdered AC,

produced from recycled solid wastes, makes no need of regeneratingthe spent carbon.

Applications of Activated Carbon

There is no particular AC that is effective for all purposes.

*In odour controi

As a decolourantIn solution purification

In gas masks-to adsorb poisoning gases.

In Air Conditioning-to control odour.

In industrial recovery

Activated carbon adsorbs practically any organic solvent at

about 35 oC and releases it when heated to 120oC or higher for solvent

recovery.

*In cigarette filters-Specially impregnated are used.

In the removal of organic and inorganic compounds

It is generally used for the removal of the refractory organic

compounds as well as residual


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amounts of inorganic compounds such as nitrogen, `sulfides and

heavy metals.

In odour control :

Activated carbon adsorbets are commonly used for odour

control . activated carbon has different rate of adsorption for

different substances.

In soln purification

Activated carbon is also used in cleaning sugar soln.

In gas masks

The vapour adsorbent type of activated carbon is used in gas

masks.

Activated carbon is also effective in adsorbing organic molecules

even from humid gas and stream.

Role of adsorbents in ion exchange adsorption :

Ion exchange adsorption is defined as the process of

releasing the ion and adsorbing another like ion.

Classification of ionexchangers:

1.cation exchanger

2.Anion exchanger

Softening(or)conditioning method:


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The process of removing hardness producing salts from

water is known as softening(or)conditioning of water.

This method can be done in 2 methods

1.External conditioning

2.Internal conditioning

External conditioning:

Ion exchange (or)demineralization process.

Cation exchanger:

Resins containing acdic functional groups (COOH, SO3H ) are

capable of exchanging their H+ Ions with other cations .cation

exchange resins is represented as

1.sulphonated coals.

2.sulphonated polystyrene RSO3H

Anion exchanger:

Resins contains basi functional groups (NH2,OH) are capable of

exchange their anions with other anions .anion exchange resin

represented as R(OH)2

EX:1.cross linked quaternary ammonium salts.

RH2+CaCl2RCa2HCl

RH2+mgso4RmgH2SO4

RHNaClRNaHCl


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Regeneration:

RCa2HClRH2+CaCL2

RNaHClRHNaCl

RCl22NaOHR(OH)2+2NaCl

Carbonate conditioning: scale formation can be avoided by adding

Na2CO3 to the boiler water.

CaSO4+Na2CO3CaCO3+Na2SO4

Phosphate conditioning: scale formation can be avoided by addingsodium phosphate.

3CaSO4+2Na3po4Ca3(po4)2

Trisodiumphospate Na3po4(Weaklyalkaline) used for too acidic water.

Disodium hydrogen phosphate-Na2HPO4(weakly alkaline) used for alka

weakly acdic water.

Sodium dihydrogen phosphate-NaH2PO4(acidic) used for alkaline

water.


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Calogen conditioning

Calogen is sodium hexa meta phosphateNa2[Na4(PO3)6]

2Caso4+Na2[Na4(po3)6+Na2[Ca2(PO3)6]+2Na2SO4

The complex Na2[Na4(po3)6] is soluble in water and ther is no problem

of sludge disposal. So calogen conditioning is better than phosphate

conditioning.

Zeolite process:

Hard water contains Ca2

+&Mg2

+ ions this ions form hard soap(in soluble)with soap which does not produce lather with soap soln.

Hard water is softened by passing it through a column packed with

sodium cation exchange resin (called sodium zeolite )


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Na2Ze+Ca2CaZe2Na

Synthetic zeolite is represented by Na2Ze. The sodium ions which are

loosely held in Na2Ze are replaced by Ca2+

and Mg2+

ions present in the

water.

Process:

Sodium ions with Ca2+

and Mg2+

ions present in the water to form Ca

and Mg ions present in the water.

Ca(HCO3)+Na2Ze CaZe+2NaHCO3

Mg (HCO3)+Na2Ze MgZe2NaHCO3

CaSO4+ Na2Ze CaZeNa2SO4


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Mg SO4+ Na2Ze Mg ZeNa2SO4

CaCl2 +Na2Ze CaZe2NaCl

Mg Cl2 +Na2Ze Mg Ze+2NaCl

Regeneration:

CaZe+2Na+Cl

-Na2Ze

1.water softening (demineralization process)

The hard water first passed through a cation exchange

column .which adsorbs all the cations like Ca

2+

,Mg

2+

RH2+CaCl2RCa2HCl

RH2 +Mgso4RMg H2SO4

Regeneration:

RCa 2HClRH2+ CaCl2

RNa +HCl RH NaCl

CaZe+ 2Na+

Cl- Na2Ze +CaCl2

Electrical demineralization of water

Ion exchange resins supported on paper or fibre can be used

as membranes called ion selective membranes.


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Process: the cation selective membrane permits only cations

but not anions .anion selective membrane permits only anion

but not cation.

Medical uses:

Excess sodium salts from the body fluids can be removed by

giving a patient a suitable ion exchanger to eat.

Weakly basic anion exchanger are used to remove excess

acid (or)acidity in the stomach.


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Unit-III

PART A

1. Define adsorption and adsorbate.

2. What is a chemisorption. Give example?

3. What is physisorption? Give example.

4. Mention some important characteristics of adsorption.

5. How will you increase the activity of an adsorbent?

6. Explain the effect of temperature on adsorption.

7. What is Freundlich adsorption isotherm?

8. Explain the limitation of Freundlich adsorption isotherm.

9. Write the mathematical expression of Langmuir isotherm.

10. What is the demerit of Langmuir adsorption isotherm?

11. What are promoters?

12. What is catalytic poisoning?

13. What is the effect of temperature and pressure on the adsorption of hydrogengas on charcoal?

14. How is arsenic poisoning removed from the body?

15. Define ion exchange adsorption.

16. How is evaporation of water in lake is minismised?

17. What is the role of adsorbent in catalysis?

18. Define adsorption isotherm.

19. Mention any three factors of affecting adsorption of gases on solids.

20. (a)Give any two applications of adsorption.

(b)What is critical temperature?


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(c)Define Enthalpy of adsorption.

(d)What is effect of temperature of gas in adsorption?

(e)Define Freundlich Adsorption isotherm.

(f) Mention any four postulates of Langmuirs adsorption isotherm

PART B

Explain the role of adsorbents in catalytic adsorption.

1. Derive the Langmuir adsorption isotherm and interpret the results.

2Distinguish between physisorption and chemisorption.

3. Write a note on adsorption of solute from solution.

4. Write a note on application of adsorption.

5. What are the factors affecting gases on solids in adsorption.

6. State and derive the expression for Freundlich adsorption isotherm.

7. Explain treatment of polluted water by using powdered activated carbon.

8. Describes Zeolite process of Adsorption.

9. What are the characteristics of adsorption?


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UNIT IV NON CONVENTIONAL ENERGY SOURCES AND

STORAGE DEVICES

Nuclear energyfission and fusion reactionsLight water nuclear

reactor for powergeneration (Block diagram only)Breeder reactorSolar energy

conversionSolar

cellsWind energyFuel cellsHydrogenOxygen fuel cell

BatteriesAlkaline

batteriesLead acid storage batteryNickelCadmium and Lithium

batteries.


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UNIT -4

NON CONVENTIONAL ENERGY SOURCES AND STORAGE

DEVICES

Nuclear fission: It is the nuclear reaction in which heavy

isotopes are split into lighter nuclei on bombardment by

neutrons. Fission reaction of U235

is given below

92U

235

+0n1 36Kr

92

+ 56Ba

141

+ 3 0n

1

+ energy

(Structure of fission reaction)


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Nuclear fusion: Process of combination of lighter nuclei

into heavier nucles with simultaneous liberation of large

amount of energy. (e.g) solar system

1H2

+ 1H2 2 He

4+ Energy

Nuclear fusion reaction occurs in sun.

Differences between fission and fusion reaction

S.No Nuclear fission Nuclear fusion

1 It is a process of breaking a

heavier nucleous.

It is a process of

combination of lighter

nuclei.

2 It emits radioactive rays It does not emit any kind

of radioactive rays3 The mass number and

atomic number of new

elements are lower than

The mass number and

atomic number of

product is higher than

that of starting elements

4 It occurs at ordinary

temperature

It occurs at high

temperature

5 It gives rise to chainreaction

It does not give rise tochain reaction

6 It emits neutrons It emits positrons

7 It can be controlled It canot be controlled


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Nuclear Energy

The enormous amount of energy released during the

nuclear fission is due to the loss in some mass.

During nuclear fission, the sum of the masses of the

products formed is slightly less than the sum of masses

of target species and bombarding neutron.

The loss in mass gets converted into energy according to

Einsteins equation

E = mc2

Where,

C = velocity

m= mass lose

E= energy

Light water nuclear power plant

Definition

Light water nuclear power plant is one in which

U235 feel rods are submerged in water. Here thewater acts as coolant and moderator.


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The fission reaction is controlled by inserting or

removing the control rods of B10

automatically

from the spaces I between the fuel rods

The heat emitted by U235

in the fuel core isabsorbed by the coolant

Heat is transferred to sea water and then

converted into steam.

The steam then drives the turbines, generating

electricity.

(Str of light water nuclear power plant)

BREEDER REACTOR:

A breeder reactor is a nuclear reactor that generates

new fissile or fissionable material at a greater rate than it

consumes such material. These reactors were initially (1940s

and 1960s) considered appealing due to their superior fuel

economy; a normal reactor is able to consume less than 1% of
http://en.wikipedia.org/wiki/Nuclear_reactorhttp://en.wikipedia.org/wiki/Fissilehttp://en.wikipedia.org/wiki/Nuclear_fuelhttp://en.wikipedia.org/wiki/Nuclear_fuelhttp://en.wikipedia.org/wiki/Fissilehttp://en.wikipedia.org/wiki/Nuclear_reactor


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the natural uranium that begins the fuel cycle, whereas a breeder

can utilize a much greater percentage of the initial fissionable

material, and with re-processing, can use almost all of the initial

fissionable material. Breeders can be designed to utilize thorium,which is more abundant than uranium. Currently, there is

renewed interest in breeders because they would consume less

natural uranium (less than 3% compared to conventional light-

water reactors), and generate less waste, for equal amounts of

energy, by converting non-fissile isotopes of uranium into

nuclear fuel.

Production of fissile material in a reactor occurs byneutron irradiation of fertile material, particularly uranium-238

and thorium-232. In a breeder reactor, these materials are

deliberately provided, either in the fuel or in a breeder blanket

surrounding the core, or most commonly in both. Production of

fissile material takes place to some extent in the fuel of all

current commercial nuclear power reactors. Towards the end of

its life, a uranium (not MOX, just uranium) PWR fuel element is

producing more power from the fissioning of plutonium than

from the remaining uranium-235. Historically, in order to be

called a breeder, a reactor must be specifically designed to

create more fissile material than it consumes.

Photo galvanic cell or Solar cell

Definition

Photogalvanic cell is the one , which converts the solar

energy ( Energy received from the sun) into electrical

energy.
http://en.wikipedia.org/wiki/Uraniumhttp://en.wikipedia.org/wiki/Thoriumhttp://en.wikipedia.org/wiki/Radioactive_wastehttp://en.wikipedia.org/wiki/Neutron_radiationhttp://en.wikipedia.org/wiki/Fertile_materialhttp://en.wikipedia.org/wiki/Uranium-238http://en.wikipedia.org/wiki/Thorium-232http://en.wikipedia.org/wiki/Nuclear_power_reactorhttp://en.wikipedia.org/wiki/MOX_fuelhttp://en.wikipedia.org/wiki/Pressurized_water_reactorhttp://en.wikipedia.org/wiki/Plutoniumhttp://en.wikipedia.org/wiki/Uranium-235http://en.wikipedia.org/wiki/Uranium-235http://en.wikipedia.org/wiki/Plutoniumhttp://en.wikipedia.org/wiki/Pressurized_water_reactorhttp://en.wikipedia.org/wiki/MOX_fuelhttp://en.wikipedia.org/wiki/Nuclear_power_reactorhttp://en.wikipedia.org/wiki/Thorium-232http://en.wikipedia.org/wiki/Uranium-238http://en.wikipedia.org/wiki/Fertile_materialhttp://en.wikipedia.org/wiki/Neutron_radiationhttp://en.wikipedia.org/wiki/Radioactive_wastehttp://en.wikipedia.org/wiki/Thoriumhttp://en.wikipedia.org/wiki/Uranium


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Principle

Solar cells consists of a p-type semiconductor(si with B)and n-type semiconductor(si with P)

When solar rays fall on the top layer of p-type

semiconductor, the electrons from the valence band get

promoted to the conduction band and cross the p-n

junction into n-type semiconductor.

Thereby potential difference between two layers is

created, which causes flow of electrons

(Solar cell)


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Uses:

Used in calculators, electronic watches, street lights, water

pumps to run radios and TVs.

Solar Battery

Working

When large number of solar cells are connected in series it

form a solar battery.

Solar battry produce more electricity which is enough to

run water pump, street light etc.,Uses:

They are used in remote areas where conventional

electricity supply is a problem.

Solar light


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WIND ENERGY

Moving air is called wind. Energy recovered from the forces of

wind is called wind energy.

Wind power is the conversion of wind energy into a

useful form, such as electricity, using wind turbines. At the end

of 2008, worldwide nameplate capacity of wind-powered
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generators was 121.2 gigawatts (GW). Wind power produces

about 1.5% of worldwide electricity use, and is growing rapidly,

having doubled in the three years between 2005 and 2008.

Large-scale wind farms are typically connected to the local

electric power transmission network; smaller turbines are used

to provide electricity to isolated locations. Utility companies

increasingly buy back surplus electricity produced by small

domestic turbines. Wind energy as a power source is attractive

as an alternative to fossil fuels, because it is plentiful,

renewable, widely distributed, clean, and produces no

greenhouse gas emissions; however, the construction of wind

farms (as with other forms of power generation) is not

universally welcomed due to their visual impact and other

effects on the environment.

Wind power is non-dispatchable, meaning that foreconomic operation all of the available output must be taken

when it is available, and other resources, such as hydropower,

and standard load management techniques must be used to

match supply with demand. The intermittency of wind seldom

creates problems when using wind power to supply a low

proportion of total demand. Where wind is to be used for a

moderate fraction of demand, additional costs for compensation

of intermittency are considered to be modest. Studies of a paneuropean power grid, show that wind can be used to meet eg

70% of load, over a wide area of interconnected grids, and then

the costs of electricity delivered into the consuming country are

comparable to present day power cost.
http://en.wikipedia.org/wiki/Gigawatthttp://en.wikipedia.org/wiki/Wind_farmshttp://en.wikipedia.org/wiki/Electric_power_transmissionhttp://en.wikipedia.org/wiki/Net_meteringhttp://en.wikipedia.org/wiki/Fossil_fuelhttp://en.wikipedia.org/wiki/Renewable_energyhttp://en.wikipedia.org/wiki/Greenhouse_gas_emissionshttp://en.wikipedia.org/wiki/Environmental_effects_of_wind_powerhttp://en.wikipedia.org/wiki/Hydropowerhttp://en.wikipedia.org/wiki/Load_managementhttp://en.wikipedia.org/wiki/Intermittent_power_sourceshttp://en.wikipedia.org/wiki/Intermittent_power_sourceshttp://en.wikipedia.org/wiki/Load_managementhttp://en.wikipedia.org/wiki/Hydropowerhttp://en.wikipedia.org/wiki/Environmental_effects_of_wind_powerhttp://en.wikipedia.org/wiki/Greenhouse_gas_emissionshttp://en.wikipedia.org/wiki/Renewable_energyhttp://en.wikipedia.org/wiki/Fossil_fuelhttp://en.wikipedia.org/wiki/Net_meteringhttp://en.wikipedia.org/wiki/Electric_power_transmissionhttp://en.wikipedia.org/wiki/Wind_farmshttp://en.wikipedia.org/wiki/Gigawatt


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FUEL CELLS:

A fuel cell is an electrochemical conversion

device. It produces electricity from fuel (on the anode side) and

an oxidant (on the cathode side), which react in the presence of

an electrolyte. The reactants flow into the cell, and the reaction

products flow out of it, while the electrolyte remains within it.Fuel cells can operate virtually continuously as long as the

necessary flows are maintained.
http://en.wikipedia.org/wiki/Electrochemistryhttp://en.wikipedia.org/wiki/Fuelhttp://en.wikipedia.org/wiki/Anodehttp://en.wikipedia.org/wiki/Oxidizing_agenthttp://en.wikipedia.org/wiki/Cathodehttp://en.wikipedia.org/wiki/Electrolytehttp://en.wikipedia.org/wiki/Electrolytehttp://en.wikipedia.org/wiki/Cathodehttp://en.wikipedia.org/wiki/Oxidizing_agenthttp://en.wikipedia.org/wiki/Anodehttp://en.wikipedia.org/wiki/Fuelhttp://en.wikipedia.org/wiki/Electrochemistry


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Fuel cells are different from electrochemical cell

batteries in that they consume reactant from an external source,

which must be replenisheda thermodynamically open system.

By contrast, batteries store electrical energy chemically andhence represent a thermodynamically closed system.

Many combinations of fuels and oxidants are

possible. A hydrogen fuel cell uses hydrogen as its fuel and

oxygen (usually from air) as its oxidant. Other fuels include

hydrocarbons and alcohols. Other oxidants include chlorine and

chlorine dioxide.
http://en.wikipedia.org/wiki/Battery_(electricity)http://en.wikipedia.org/wiki/Thermodynamic_systemhttp://en.wikipedia.org/wiki/Hydrogenhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Hydrocarbonhttp://en.wikipedia.org/wiki/Alcoholhttp://en.wikipedia.org/wiki/Chlorinehttp://en.wikipedia.org/wiki/Chlorine_dioxidehttp://en.wikipedia.org/wiki/Chlorine_dioxidehttp://en.wikipedia.org/wiki/Chlorinehttp://en.wikipedia.org/wiki/Alcoholhttp://en.wikipedia.org/wiki/Hydrocarbonhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Hydrogenhttp://en.wikipedia.org/wiki/Thermodynamic_systemhttp://en.wikipedia.org/wiki/Battery_(electricity)


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(HydrogenOxygen fuel cell)

ENERGY STORAGE DEVICES

Battery:

It is an arrangement of several electrochemical cells

connected in series that can be used as a source of direct

electric current.


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Secondary battery or secondary cells

In these cells, the electrode reactions can be reversed by

passing an external energy.

They can be recharged by passing electric current.

They are called storage cells or accumulators.

Ex: Lead acid storage cell, Nickel- cadmium cell.

Alkaline Battery

Here the powdered zinc is mixed with KOH and MnO2 to

get a gel

A Carbon rod acts as cathode. IT is immersed in KOHThe outside cylindrical body is made up of zinc


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Cell reactions

At anode : Zn (s) + 2OH- Zn(OH)2 + 2e-

At cathode: 2MnO2 + H2O(l) + 2e- 2OH- +Mn2O3

Overall reaction:

Zn (s) + 2MnO2 + H2O(l) Zn(OH)2 + Mn2O3

Uses: It is used in calculators, watches etc.,


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Lead storage cell

Description:

It consists of number of voltaic cells connected in seriesPb is anode and PbO2 is cathode

Number of Pb plates and PbO2 plates are connected in

parallel.

Plates are separated from adjacent ones by insulators

like rubber or glass fiber.

This arrangement is immersed in dil. H2SO4

(Lead acid Battery)


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Cell reactions

At anode : Pb (s) + SO42- PbSO4 (s) + 2e-

At cathode: PbO2(s) + SO42-

+ 4H+

+ 2e- PbSO4

+2H2O

Overall reaction:

Pb (s) + PbO2(s) + 2H2SO4 PbSO4 + H2O +

energy

Uses:

It is used to supply current mainly in automobiles

such as cars. Buses, trucks, etc.,

It is also used in gas engine ignition, telephone

exchanges, hospitals, power stations.

Nickel Cadmium Battery

Description

It consists of a cadmium anode.

a metal grid containing a paste of NiO2 acting as a cathode.

KOH is electrolyte


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Ni-Cd battery

Cell reactions

At anode: Cd(s) + 2OH- Cd(OH)2(s) + 2e-

At cathode: NiO2 + 2H2O(l) + 2e- 2OH- +Ni(OH)2 (s) +

energy

Overall reaction:

Cd(s) + NiO2 + 2H2O(l) Cd(OH)2(s) + Ni(OH)2 (s) + energy


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Uses:

It is used in calculators. Electronic flash units, transistors

and cordless appliances.

Lithium Battery

Description

It consists of a lithium anode and a TiS2 cathode.

A solid electrolyte generally a polymer is packed in

between the electrodes.

The electrolyte permits the passage of ions but not

electrons.

Cell reactions

At anode: Li(s) Li+

+ e-

At cathode: TiS2 + e- TiS2-


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Lithium Sulphur Battery

Description

It consists of a lithium anode and a graphite cathode.

A solid electrolyte generally -Alumina is packed in

between the electrodes.

Here sulphur is electron acceptor

Cell reactions

At anode: Li(s) Li+

+ e-


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At cathode: S + 2e- S2-

Overall reaction:

2Li(s) + S 2Li+ + S2-

The sulphide ions, formed, react with elemental sulphur to

form the polysulphide ion.

Uses

It is used in electric cars

Li-S battery has light weight unlike the lead acid battery.It possesses a high energy density.


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Unit 4

Part-A

1. Define nuclear fission with example.

2. Mention a few important characteristics of nuclear fission.

3. What is nuclear fusion reaction? G

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