Subject Name : ENGINEERING CHEMISTRY I Subject Code ...
Transcript of Subject Name : ENGINEERING CHEMISTRY I Subject Code ...
Subject Name : ENGINEERING CHEMISTRY I
Subject Code : 10ACH01
Year : I Year (Common to all branches)
Semester : I
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 water –requirements – Disadvantages of using
hard water in boiler – Internal conditioning(Phosphate, Carbon and
Carbonate) – External conditioning – Zeolite process –Demineralization
process – Desalination – Reverse Osmosis (Chlorination, UV
treatment, ozonation).
UNIT II POLYMERS AND COMPOSITES
Polymers – Types – Polymerization – Addition and condensation
polymerization – Free
radical polymerization mechanism – Plastics – classification-
preparation, properties and
uses of PVC, Teflon, Polyurethane, Nylon 6:6, PET, Bakelite, and
Epoxy resin –
Compounding of Plastics- Compression moulding – Injection moulding
– Composites –
definition – types of Polymer matrix composites – FRP only.
UNIT III SURFACE CHEMISTRY
Adsorption – Types – Adsorption of gases on solids – Adsorption
isotherms – Freundlich
and Langmuir isotherms – Adsorption of solids from solution – Role of
adsorption in
catalysis - Ion exchange adsorption – Pollution abatement.
UNIT IV NON CONVENTIONAL ENERGY SOURCES AND
STORAGE DEVICES
Nuclear energy – fission and fusion reactions – Light water nuclear
reactor for power
generation (Block diagram only) – Breeder reactor – Solar energy
conversion – Solar
cells – Wind energy – Fuel cells – Hydrogen – Oxygen fuel cell –
Batteries – Alkaline
batteries – Lead acid storage battery – Nickel – Cadmium and Lithium
batteries.
UNIT V ENGINEERING MATERIALS
Refractories – Classification-( acidic, basic and neutral) – Properties
(refractoriness,
refractoriness under load, porosity, dimensional stability, thermal
spalling) – manufacture
of alumina, magnesite and Zirconia bricks – Abrasives – Natural
abrasives – (Quartz,
corundum, emery, garnet, diamond) – Artificial abrasives (silicon
carbide, boron carbide)
– Lubricants- Mechanism of lubrication – Liquid lubricants – Properties
(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).
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).
UNIT I WATER TECHNOLOGY
Water – Types – Alkalinity – types of alkalinity and determination –
hardness – types –CaCO3 equivalents – Estimation by EDTA method
(problems) – Boiler feed water –requirements – Disadvantages of using
hard water in boiler – Internal conditioning(Phosphate, Carbon and
Carbonate) – External conditioning – Zeolite process –Demineralization
process – Desalination – Reverse Osmosis (Chlorination, UV
treatment, ozonation).
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:
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 per
10 6 parts of water.
Milligram per litre(mg/lit)
It is defined as the no.of milligrams of CaCO3 equivalent
hardness per 1 litre of water.
Clarke’s degree( Cl)
It is defined as the no.of parts of CaCO3 equivalent hardness
per 10 5 parts of water.
French degree( Fr)
It is defined as the no.of parts of CaCO3 equivalent hardness per
10 5 part of water.
1ppm=1mg/lit=0.10Fr=0.070cl
Alkalinity determination:
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
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
TITRATION – I
STANDARDISATION OF HCl
Exactly 20 ml of the given standard NaOH solution is pipetted out into
a 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.
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: eriochrome –black –T
Buffer soln: (NH4Cl-NH4OH):PH:8-10
*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.
Ca (HCO3)2 CaCO3 ↓+CO2 +H2O
Mg (HCO3)2 Mg(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
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
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
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
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
Sedimentation:
It is a process of removing suspended impurities by allowing
the 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+6H2O→Al(OH)3↓+3H2SO4
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 as
sterilization.
By boiling:
Water boiled for 10-15minitues all the harmful bacteria are
killed and the water becomes safe for use.
By ozonation
O3→O2+[O]
Ozone is a powerful disinfectant and is readily absorbed by water,
By using UV radiation
Using for sterlisizing water in swimming pool.
Cl2+H2O→HCl+HOCl
Cl2+NH3→ClNH2+HCl
ClNH2+H2O→HOCl+NH3
CaOCl2+H2O→Ca(OH)2+Cl2
Cl2+H2O→HCl+HOCl
HOCl+Bacteria→bacterias are killed
Break point chlorination:
Water contains following impurities:
1.bacterias
2.organic impurities
3.redusing substances(Fe2+,H2S etc)
4.Free ammonia
Boiler feed water:
The water feed into the boiler fo the production of steam is called
boiler 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
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 .
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+H2O→2NaOH+CO2
Fe+2NaOH→Na2Feo2+H2↑
Boiler corrosion:
Corrosion in boilers is due to the presence of →→
1.Dissolved o2
2.Dissolved CO2
3.Dissolved salts
4Fe+6H2O+3O2→4Fe(OH)3
2Na2SO3+O2→2Na2SO4
N2H4+O2→N2+2H2O
Mechanical de-aeration method:
The high temperature &low pressure produced inside the tower
dissolved oxygen content of the water.
CO2+H2O→H2CO3
2NH4OH+CO2→ (NH4)2CO3+H2O
MgCl2+2H2O→Mg(OH)2+2HCl
Fe+2HCl→FeCl2+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+CaCl2→RCa+2HCl
RH2+mgso4→Rmg+H2SO4
RH+NaCl→RNa+HCl
Regeneration:
RCa+2HCl→RH2+CaCL2
RNa+HCl→RH+NaCl
R’Cl2+2NaOH→R’(OH)2+2NaCl
Carbonate conditioning: scale formation can be avoided by adding
Na2CO3 to the boiler water.
CaSO4+Na2CO3→CaCO3+Na2SO4
Phosphate conditioning: scale formation can be avoided by adding
sodium phosphate.
3CaSO4+2Na3po4→Ca3(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.
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 )
Na2Ze+Ca2+→CaZe+2Na+
Synthetic zeolite is represented by Na2Ze. The sodium ions which are
loosely held in Na2Ze are replaced by Ca2+ and Mg 2+ ions present in the
water.
Process:
Sodium ions with Ca2+ and Mg 2+ ions present in the water to form Ca
and Mg ions present in the water.
Ca(HCO3)+Na2Ze→ CaZe+2NaHCO3
Mg (HCO3)+Na2Ze→ MgZe+2NaHCO3
CaSO4+ Na2Ze→ CaZe+Na2SO4
Mg SO4+ Na2Ze→ Mg Ze+Na2SO4
CaCl2 +Na2Ze→ CaZe+2NaCl
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 of dissolved solids
2.Brackish water-contains >1000ppm but <35000ppm of dissolved
solids .
3.sea water –contains>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 .
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 non –ionic ,colloidal impurities
3.Due to low capital cost,simplicity.
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 it’s uses?
(b). What is calgon conditioning?
(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.
UNIT II POLYMERS AND COMPOSITES
Polymers – Types – Polymerization – Addition and condensation
polymerization – Free
radical polymerization mechanism – Plastics – classification-
preparation, properties and
uses of PVC, Teflon, Polyurethane, Nylon 6:6, PET, Bakelite, and
Epoxy resin –
Compounding of Plastics- Compression moulding – Injection moulding
– Composites –
definition – types of Polymer matrix composites – FRP only.
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-
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 ……
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 → - n…CH2- 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
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)6 –NH2 +n HOOC –(CH2)4 -COOH→ -[HN-
(CH2)6 –NH–CO –CH2- CO -]n(Nylon 6:6)
copolymerization:
it is the joint polymerization in which 2(or) more different
monomers combine to give a polymer.
nCH2=CH –CH =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
2.Thermosetting plastics ex:Bakelite, polyester
Thermoplastic resin:
Thermoplastic can be softened on heating and hardened on
cooling. 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.
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 (3500 C), very high chemical inertness and
thermal stability
( 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:
It is less stable than polyamide.
It is easily affected by moisture.
It is characterized by excellent resistance to abrasion and solvents.
Uses:
1.perlon –U 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.
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 commercial
fibres.
The fibres posses high stretch resistance ,high –crease 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.
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.
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 ,cross –linked
polymer called Bakelite.
Properties
Bakelite is resistant to acids ,salts and most organic solvent,but it
is attacked by alkalis because of the presence of –OH groups.
Uses
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.
.
Compounding of plastics:
Compounding of plastics is a process by which polymer resi
ns are mixed with some additives like fillers ,plasticizers etc .
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
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:
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 from
the 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
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 methods
described 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 is
usually 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
Materials Properties Improved
Glass Fibers UP, EP, PA, PC, POM,
PP, PBT, VE
Strength, Elastic, heat
resistance
Carbon and
Aramid Fibers EP, UP, VE, PA Elasticity, Tensile Strength
Inorganic
Particulates
Semicrystalline
Thermoplastics, UP
Isotropic shrinkage,
abrasion, compression
strength
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
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.
UNIT III SURFACE CHEMISTRY
Adsorption – Types – Adsorption of gases on solids – Adsorption
isotherms – Freundlich
and Langmuir isotherms – Adsorption of solids from solution – Role of
adsorption in
catalysis - Ion exchange adsorption – Pollution abatement.
Unit:3
Surface chemistry
Adsorption is the phenomenon of concentration of molecules of a gas 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
adsorpation .
Types of adsorption:
1.physical adsorption
2.chemical adsorption
DIFFERENCES BETWEEN PHYSISORPTION AND CHEMISORPTION
Physisorption chemisorption
It is caused by intermolecular vanderwaals forces(weak)
It is caused by chemical bond formation
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.
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)
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 waal’s 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.
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 of
chemical 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:
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.
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 area Surface 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.
ADSORPTION ISOTHERMS
Definition: Adsorption isotherm is a relationship (or a graph) between
magnitude of adsorption with pressure at constant temperature
FREUNDLICH’S 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 = KP 1/n
DERIVATION OF FREUNDLICH’S 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 P 1/n
(or) x/m = KP1/n …………………….(1)
where, n= whole number.
(1) This eqn(1)is called Freundlich’s 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 FREUNDLICH’S
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.Freundlich’s adsorption isotherm fails, when the concentration of
adsorbate is very high.
LANGMUIR’S ADSORPTION ISOTHERM
Langmuir derived an equation based on some theoretical
considerations.
The postulates (or) assumptions of langmuir,s theory are
1.Valencies at the surface of adsorbent are not fully satisfied.
2.The adsorbed gas layer on the solid surface is only one molecule
thick.
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 between
adsorption and desorption. If A is gas molecule and M is surface then,
ka
A(g) + M(surface) AM
kd
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
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
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 = K’KP
x
1 + KP = P
K’K K’K x
1 + K P = P
K’K K’K 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/k’k
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, k’k
i.e., 1 K P
K’K K’K
Hence equation (5) becomes
1 = P
K’K x (or) x = PK’K ……………(6)
ie., amount of adsorption per unit weight of adsorbent is directly
proportional to the ‘P’ at high 1 term is negligible,
K’K
K P 1
K’K K’K
Hence equation (5) becomes
K P = P
K’K 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.
Case (iii) At normal pressure: At normal (intermediate) pressure the
equation (7) becomes
X=K’Pn ………………(8)
Where, n lies between 0 and 1.
Equation (8) is Freundlich’s adsorption isotherm.
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.
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) CONTACT THEORY
1.Action of heterogeneous catalyst:
Hydrogenation of ethylene using Ni catalyst.
Step :1
Adsorption of reactant molecule
Step:2
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
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.
(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
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 sustain
combustion.
Step II: Activation of 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.
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 is highly 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.
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
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 .
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.
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 through
granular medium filters may be required.
Regeneration of Activated Carbon
Thermal methods are widely and effectively used.
(i)Granular carbon It can be regenerated easily in a furnace by heating
in 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 regenerating
the spent carbon.
Applications of Activated Carbon
There is no particular AC that is effective for all purposes.
*In odour controi
As a decolourant
In 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 120 oC 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
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 ion –exchangers:
1.cation exchanger
2.Anion exchanger
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 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+CaCl2→RCa+2HCl
RH2+mgso4→Rmg+H2SO4
RH+NaCl→RNa+HCl
Regeneration:
RCa+2HCl→RH2+CaCL2
RNa+HCl→RH+NaCl
R’Cl2+2NaOH→R’(OH)2+2NaCl
Carbonate conditioning: scale formation can be avoided by adding
Na2CO3 to the boiler water.
CaSO4+Na2CO3→CaCO3+Na2SO4
Phosphate conditioning: scale formation can be avoided by adding
sodium phosphate.
3CaSO4+2Na3po4→Ca3(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.
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 )
Na2Ze+Ca2+→CaZe+2Na+
Synthetic zeolite is represented by Na2Ze. The sodium ions which are
loosely held in Na2Ze are replaced by Ca2+ and Mg 2+ ions present in the
water.
Process:
Sodium ions with Ca2+ and Mg 2+ ions present in the water to form Ca
and Mg ions present in the water.
Ca(HCO3)+Na2Ze→ CaZe+2NaHCO3
Mg (HCO3)+Na2Ze→ MgZe+2NaHCO3
CaSO4+ Na2Ze→ CaZe+Na2SO4
Mg SO4+ Na2Ze→ Mg Ze+Na2SO4
CaCl2 +Na2Ze→ CaZe+2NaCl
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+CaCl2→RCa+2HCl
RH2 +Mgso4→RMg +H2SO4
Regeneration:
RCa +2HCl→RH2+ 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.
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.
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 hydrogen gas 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?
(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 Langmuir’s 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?
UNIT IV NON CONVENTIONAL ENERGY SOURCES AND
STORAGE DEVICES
Nuclear energy – fission and fusion reactions – Light water nuclear
reactor for power
generation (Block diagram only) – Breeder reactor – Solar energy
conversion – Solar
cells – Wind energy – Fuel cells – Hydrogen – Oxygen fuel cell –
Batteries – Alkaline
batteries – Lead acid storage battery – Nickel – Cadmium and Lithium
batteries.
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
92U235 +0n1 → 36Kr92 + 56Ba141 + 3 0n1 + energy
(Structure of fission reaction)
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 He4 + 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 rays
3 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 chain reaction
It does not give rise to chain reaction
6 It emits neutrons It emits positrons 7 It can be controlled It canot be controlled
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 the water acts as coolant and moderator.
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 U 235 in the fuel core is absorbed 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
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 by
neutron 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.
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)
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
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
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 for
economic 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 pan
european 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.
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.
Fuel cells are different from electrochemical cell
batteries in that they consume reactant from an external source,
which must be replenished – a thermodynamically open system.
By contrast, batteries store electrical energy chemically and
hence 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.
(Hydrogen – Oxygen 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.
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 KOH
The outside cylindrical body is made up of zinc
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.,
Lead storage cell
Description:
It consists of number of voltaic cells connected in series
Pb 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)
Cell reactions
At anode : Pb (s) + SO42- → PbSO4 (s) + 2e-
At cathode: PbO2(s) + SO42- + 4H+ + 2e- → PbSO4
+ 2 H2O
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
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
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-
Overall reaction:
Li(s) + TiS2 → Li+ + TiS2-
Other types of secondary lithium batteries
(i) Li/ MnO2 (ii) Li/V2O5 (iii) Li/MoO2 (iv) Li/Cr3O8
Advantages of Li battery
It is the cell future. Why?
Its cell voltage is high, 3.0V
Since Li is a light weight metal, only 7kg material required to produce 1mole of electrons.
Since all the constituents of the battery are solids, there is no risk of leakage from the battery.
This battery can be made in a variety of shapes and sizes.
Disadvantages of Li battery
Li battery is more expensive than other batteries
Uses
Button sized batteries are used in calculators, watches,
cameras, mobile phones, laptop computers.
Lithium Sulphur Battery
Description
It consists of a lithium anode and a graphite cathode.
A solid electrolyte generally β-Alumina is packed in between the electrodes.
Here sulphur is electron acceptor
Cell reactions
At anode: Li(s) → Li+ + e-
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.
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? Give an example.
4. What is nuclear chain reaction?
5. Give any two differences between nuclear fission and nuclear fusion reaction.
6. What is critical mass?
7. What are super and sub critical mass?
8. What are the types of nuclear fission reactions?
9. What is a nuclear reactor?
10. What is light water nuclear power plant?
11. What are moderators? Give example.
12. What are fissile and fertile nucleides?
13. What is breeder reactor?
14. What is photo galvanic cell?
15. What are fuel cells?
16. Give the advantages of wind energy.
17. What is a battery? How does it differ from a cell?
18. What is a primary battery? Give example.
19. What are secondary cells?
20.(a)Write the charging and discharging reaction of lead accumulator?
(b)Write the cell representation of Ni-Cd Battery.
(c ) List any two advantages of Li battery.
(d)Li Battery is the cell of future. Comment on it.
(e)What are the advantages of alkaline battery over dry battery?
(f)What is wind energy?
PART B
1. Write note on Ni-Cd battery.
2. Explain the construction and working of Lead acid battery.
3. Write short note on wind energy.
4. Describe the construction and working of H2-O2 fuel cell.
5. State the principle and applications of photo galvanic cell.
6. What is nuclear reactor? Explain the various components of light water nuclear power plant with a suitable block diagram.
7. What is breeder reactor? Explain with an example.
8 . Explain the construction and working of alkaline battery.
9. Write notes on Li Battery.
10. Explain the following with example.
(i)Nuclear fission (ii) nuclear fusion (iii) Nuclear energy
UNIT V ENGINEERING MATERIALS
Refractories – Classification-( acidic, basic and neutral) – Properties
(refractoriness,
refractoriness under load, porosity, dimensional stability, thermal
spalling) – manufacture
of alumina, magnesite and Zirconia bricks – Abrasives – Natural
abrasives – (Quartz,
corundum, emery, garnet, diamond) – Artificial abrasives (silicon
carbide, boron carbide)
– Lubricants- Mechanism of lubrication – Liquid lubricants – Properties
(Viscosity,
viscosity index, flash and fire points, cloud and pour points, oilness ,
aniline number) –
solid lubricants (graphite & molybdenum disulphide).
UNIT 5
ENGINEERING MATERIALS
REFRACTORIES
Materials that can withstand high temp without softening and
deformation in their shap.
Used for the construction of furnaces, converters, kilns,
crucibles, ladles etc.
CHARACTERISTICS
Infusible at operating temp.
Chemically inert towards corrosive gases, liquids etc.
Should not suffer change in size at operating temp.
Should have high refractoriness
Should have high load bearing capacity at operating temp.
CLASSIFICATION
Based on chemical nature
Acidic refractories – Eg. Silica and Alumina
Basic refractories – Eg. Magnesite and Dolomite
Neutral refractories – Eg. Graphite and Carborundum
Based on refractoriness
Low heat duty refractories
Intermediate heat duty refractories
High heat duty refractories
Super heat duty refractories
PROPERTIES
Refractoriness - It is the ability to withstand very high temp.
without softening or deformation under particular service
condition.
Since most of the refractories are mixtures of several metallic
oxides, they do not have a sharp melting point. So the
refractoriness of a refractory is generally measured as the
softening temperature and is expressed in terms of pyrometric
cone equivalent.(PCE).
Pyrometric cone equivalent is the number which
represents the softening temperature of a refractory specimen
of standard dimension (38mm height and 19mm triangular
base) and composition.
Objectives of PCE test
To determine the softening temperature of a test refractory material.
To classify the refractories
To determine the purity of the refractoreies
To check whether the refractory can be used at particular servicing temperature.
Refractoriness is determined by comparing the softening
temperature of a test cone with that of a series of segar cones.
Segar cones are pyramid shaped standard refractory of definite
composition and dimensions and hence it has a definite
softening temperature.
A test cone is prepared from a refractory for which the
softening temperature to be determined, as the same
dimensions of segar cones.
Then the test cone os placed in electric furnace. The furnace is
heated at a standard rate of 100C per minute, during which
softening of segar cones occur along with test cone. The
temperature at which the apex of the cone touches the base is
taken as its softening temperature.
RUL – Refractoriness Under Load
The temp. at which a std dimensioned specimen of a refractory
undergoes 10% deformation with a constant load of 3.5 or 1.75
Kg/cm2
The load bearing capacity of a refractory can be measured by
RUL test.
A good refractory should have high RUL value
Porosity – ratio of pore volume to the bulk volume
P = (W- D/W- A) X 100
W – weight of saturated specimen in air
D – weight of dry specimen
A – weight of saturated specimen in water
Porosity reduces strength, corrosion resistance thermal
conductivity, thermal spalling and abrasion resistance
Thermal spalling – property of breaking, cracking or peeling of
refractory material under high temp.
Thermal spalling may be due to rapid change in temp. or slag
penetration
A good refractory should show good resistance to thermal
spalling
Dimensional stability
Resistance of refractory to any volume change when exposed
to high temp. over a prolonged time
Refractories may undergo reversible or irreversible dimensional
changes
A good refractory should show minimum level of reversible
dimensional changes with temp.
ALUMINA BRICKS
Contain 50% of aluminium oxide
Manufacture
Calcined bauxite, silica and grog (calcined fire clay) are ground
well and mixed with water
The pasty mass is converted into bricks by mechanical pressing
or slip casting
The bricks are dried and fired at about 1200 to 14000 C for 6-8
days
MAGNESITE BRICKS
Contain maximum Magnesium oxide
Manufacture
Calcined magnesite, magnesia or iron oxide are ground well and
mixed with water
The pasty mass is converted into bricks by mechanical pressing
or slip casting
The bricks are dried and fired at about 15000 C for 8 hours then
cooled slowly
ZIRCONIA BRICKS
Contain zirconite
Manufacture
Zirconite mineral, colloidal zirconia or alumina are ground well
and mixed with water and made into bricks. Small amount of
MgO or CaO is added as stabilizer. The bricks are dried and
fired at about 17000 C
ABRASIVES
Abrasives are very hard substances used for grinding, shaping and polishing other materials
PROPERTIES Have very high melting point Chemically inert High abrasive power (ability to scratch away pr sharp other
materials) Sometimes hard and brittle or soft and flexible
ABRASIVES - TYPES natural abrasives – Eg. Diamond, corundum synthetic abrasives – Eg. carborundum, norbide
Hardness is measured in terms of moh’s scale. -diamond is taken as the reference and hardness of other
materials are determined -abrasives with moh’s scale 1-4 are called soft abrasives NATURAL ABRASIVES Diamond:
o Purest crystalline carbon - Hardest natural substance o Moh’s scale value is 10 -Superior chemical inertness o Used in grinding wheels, drilling tools, cutting glasses,
etc Corundum
Pure crystalline form of alumina - Moh’s scale value is 9 - Used in grinding glass, gems etc.
Emery
55-75% alumina, 20-40% magnetite, 12% others - Black and opaque
-Mho’s scale value is 8 - Used for making abrasive paper,
abrasive cloth, etc.
Quartz
Pure silicone - Moh’s scale value is 7 - Used in painting industries
Garnet
Trisilicates of alumina, magnetite and Fe oxide Used for the manufacture of abrasive paper and cloth
ARTIFICIAL ABRASIVES
Silicon Carbide (SiC)
Manufacture
Silicon Carbide is manufactured by heating sand (60%)and
coke (40%) with some saw dust and a little salt in an electric
furnace to about 1500°C
SiO2 + 3C SiC + 2CO
The silicon carbide removed from the furnaces, is then mixed
with bonding agent(clay, silicon nitride) and than shaped,
dried and fired.
Properties
1. Silicon carbide posseses a high thermal conductivity, low expansion and high resistance to abrasion and spalling. 2. They are mechanically strong. Moh’s scale value is 9 . 3. Bear very high temp. 1650°C
4. Has thermal conductivity between metals and ceramics – They are electrically intermediate between conductors and
insulators.
Uses
1. Silicon carbide are used as heating elements in furnaces in the form of rods or bars.
2. They are also used for partition wall of chamber kilns, coke ovens, muffle furnaces and floors of heat treatment furnaces.
3. Sic bonded with tar are excellent for making high conductivity crucible.
Norbide or Boran Carbide (B4C)
Manufacture
It is prepared by heating a mixture of boran oxide (B2O3)
and coke in an electric furnace to about 2700°C
B2O3 +7C B4C + 6CO
Properties
1. Its hardness is 9 on moh’s scale. 2. It is light weight and black coloured compound. 3. It is highly resistant to chemical attack and erosion. 4. It resists oxidation much better than diamond.
Uses
It is used as hard materials for making grinding dies, and for cutting and sharpening hard high speed tools.
It is used to prepare scratch and wear resistant coating.
LUBRICANTS
Substances used to reduce friction between two moving
surfaces
Eg. Grease, oil etc
Lubrication
Lubrication is a process of reducing friction and wears
between two moving surfaces by adding lubricant in between
them.
Functions of a lubricant
Prevents the direct contact between the moving surfaces and
reduce wear, tear and surface deformation
Reduce wastage of energy
Prevents expansion of metals
Acts as coolant between moving surfaces
Acts as sealing agent
Minimizes corrosion
Classification
Liquid lubricants
Animal oils - e.g whale oil, tallow oil etc
vegetable oils- e.g palm oil, caster oil etc
mineral oils – e.g petroleum fractions
synthetic lubricants – Silicones, poly glycol ethers
blended oils - e.g mineral oils with additives semi solid lubricant – Eg. Greases, vaselines etc.
solid lubricant – Eg. Graphite, Molybdenum di sulphide
Emulsion - Eg. Cooling liquids, cutting emulsions
Properties
Viscosity Index
The rate of change of viscosity with temp. is indicated by a scale
known as viscosity index. The average decrease in viscosity of
an oil per degree rise in temp. between 100 and 210 F
A good lubricant should have minimum change in viscosity for a
wide range of temp. and also it should high V.I.
V.I. of a lubricant can be in creased by adding polymers like
polyisobutylene.
L - U
V.I. = -------
L – H
U is the viscosity of the test oil at 100 F
L is the viscosity of the low grade oil at 100 F (The low grade oil
should have same viscosity as that of the test oil at 210 F)
H is the viscosity of the high grade oil at 100 F (The high grade
oil should have same viscosity as that of the test oil at 210 F)
Flash and Fire points
Flash point is the lowest temp. at which the oil gives
enough vapour that gets ignited for a moment when a
small flame is brought near it.
Fire point is the lowest temp. at which the vapor of the oil
burns continuously for atleast 5 seconds when a small flame is
brought near it.
A good lubricant should have high flash and fire points than the
operating temp.
Flash and Fire points can be determined by using Pensky
Martin’s apparatus or Cleve land’s apparatus.
Cloud and Pour points
When an oil is cooled, the temp. at which the oil becomes
cloudy is called cloud point
The temp. at which the oil ceases to flow or pour is called pour
point
A good lubricant should have low cloud and pour points
Pour point can be reduced by adding pour point depressant or
by dewaxing process
Oilness
Oilness is the ability of lubricating oil to stick on to the surface
of machinery parts under heavy load or pressure
A good lubricant should have high oilness so that it is not
squeezed out of the machinery parts.
Solid lubricants
Solid lubricants are used under
high operating temp.
contamination by impurities should be avoided
combustion of lubricants should be avoided
Graphite
Graphite consists of flat layers of hexagonal arrangement of
carbon atoms. The carbon atoms are bonded by covalent
bonds and the layers are attached held together by
Vanderwall’s force of attraction. The layers can slide one over
the other easily. This property of graphite makes it a good
lubricant.
(Structure of Graphite)
Graphite can be used up to a temp. of 3750 C. It can
be used as dry powder or colloidal dispersion. Graphite in
water is called aqua dag and that in oil is called oil dag.
Graphite is generally used in internal combustion engines, air
compressors and food processing units. It is also used in
railway tracks, lathes and gears.
Molybdenum di sulphide
Molybdenum di sulphide has a sandwiched structure.
Molybdenum layer is sandwiched between two sulphur layers.
The layers are held together by vanderwaals force of attraction.
The Mo layers slide on the sulphur layers. MoS2 is used under
heavy load and high temp. It can be used up to a temp. of
800 0 C.
(Structure of Molybdenum di sulphide)
Uses
Pure MoS2 is used in the vacuum of outer space. It is also used in heavy machinery working at high
temperature.
Unit-V
PART A
1. Explain Moh’s scale for different abrasives. 2. What is hardness of abrasives? Give its units. 3. What is emery? 4. What is meant by refractoriness of refractory? 5. How are refractories classified? Give examples for each type. 6. What is RUL? 7. Define viscosity index. 8. Define lubrication. 9. What is Extreme Pressure lubrication? 10. Define cloud and pour point. 11. What is the significance of oilness? 12. What are soft abrasives? 13. What is abrasive power? 14. How are abrasives used? 15. What is diamond? Mention its types. 16. Define liquid lubricants. 17. What is acid refining process? 18. Define blended oil. 19. Differenciate between oildag and aquadag.
20. What should be flash point of a good lubricant?
PART B 1. silicon carbide bricks prepared? Give it properties and uses. (8) 2. What is carborundum? Give preparation properties of Boron carbide. (8) 3. Describe the any four properties of refractories. (8) 4. Discuss the manufacture and properties of alumina and magnesite bricks.
(8) 5. Write note on flash and fire point. Give its significance.(8) 6. Discuss the mechanism of thick film (Hydrodynamic) and thin layer
(Boundary layer) of lubrication. (8) 7. What are solid lubricants? When are they used? Explain the structure of
any one solid lubricant. (8) 8. How does Graphite act as a good lubricant? Explain. (8) 9. Explain the types of lubricants. (8)
10. Draw the structure and functions of Molybdenum disulphide. (8)
I B.Tech Semester Supplimentary Examinations, June 2009 ENGINEERING CHEMISTRY ( Common to Mechanical Engineering, Mechatronics, Production Engineering and Automobile Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆ 1. Give an account of the various methods involved in the treatment of potable water. [16] 2. (a) Explain the cold lime soda process and hot lime soda process. What are the advantages of lime soda process? (b) 100 ml of a water sample contains hardness equivalent to 25 ml of 0.08 N MgSO4. [8+8] i. What is the hardness of water sample in ppm? ii. What is the amount of lime and soda required for the treatment of the water sample? 3. Write short notes on the following: (a) Cathodic protection (b) Caustic embrittlement corrosion. [8+8] 4. Discuss the following: [16] (a) Galvanization (b) Cementation (c) Chromizing. 5. (a) Identify the thermo sets and thermoplastics among the following: i. PVC. ii. Polyethylene. iii. Silicone. iv. Polyester fibre. v. Bakelite. (b) What is bakelite? How is it manufactured and mention its uses? [5+11] 6. (a) Bring out the differences between fluid film and boundary lubrications. (b) What is online point? Mention its significance. (c) Write a short note on thin-film lubrication. [5+5+6] 7. (a) What is meant by the term lubrication ? (b) Define the following: i. lubricant ii. Friction iii. Seizure. (c) What is surface roughness, surface attraction and surface energy? [2+8+6] 8. (a) Explain the recovery of by-product from ‘Coke oven gas’ (b) Give the comparison between solid, liquid and gaseous fuels. [8+8]
I B.Tech Semester Supplimentary Examinations, June 2009 ENGINEERING CHEMISTRY
( Common to Mechanical Engineering, Mechatronics, Production Engineering and Automobile Engineering)
Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks 1. (a) What is meant by carbonate and non-carbonate hardness of water? (b) Explain why hard water does not produce leather with soap? (c) A sample of hard water contains the following dissolved solids per litre. Ca(HCO3)2 =16.4 mgs, Mg(HCO3)2 = 14.6 mgs, CaCl2 = 111 mgs, MgSO4 = 12 mgs, CO2 = 44 mgs and CaSO4 =13.6 mgs. Calculate temporary and permanent hardness of water in ppm and in degree clank. [6+4+6] 2. Explain the basic principle, different methods, advantages and disadvantages of lime-soda process. [16] 3. Explain how corrosion control can be brought about by the following methods. (a) Modifying the environment (b) Cathodic protection. [8+8] 4. Explain the following terms: [16] (a) Drying oil (b) Thinners (c) Driers (d) Fillers. 5. (a) What are heterochain polymers? Give examples. (b) What are Antioxidants? How are they useful in compounding of resins? (c) Write a note on Buna- N Rubber. [4+6+6] 6. Write a note on lubricants with special reference to their classification, mode of action, examples and applications. [16] 7. Describe the various types of lubrication. [16] 8. (a) Define a Fuel? How chemical fuels are classified and give examples for each. (b) What is meant by Calorific value of a fuel? Define calorie and kilocalorie. [10+6]
I B.Tech Semester Supplimentary Examinations, June 2009 ENGINEERING CHEMISTRY
( Common to Mechanical Engineering, Mechatronics, Production Engineering and Automobile Engineering)
Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks 1. (a) What is meant by carbonate and non-carbonate hardness of water? (b) Explain why hard water does not produce leather with soap? (c) A sample of hard water contains the following dissolved solids per litre. Ca(HCO3)2 =16.4 mgs, Mg(HCO3)2 = 14.6 mgs, CaCl2 = 111 mgs, MgSO4 = 12 mgs, CO2 = 44 mgs and CaSO4 =13.6 mgs. Calculate temporary and permanent hardness of water in ppm and in degree clank. [6+4+6] 2. Write short notes on the following: [16] (a) Colloidal conditioning (b) Sodium aluminate condition (c) Calgon conditioning (d) Carbonate conditioning. 3. Give an account of any eight factors that influence the rates of corrosion. [16] 4. Write note on: [16] (a) Phosphate coatings (b) Chemical oxide coatings (c) Anodized coatings. 5. (a) What is PVC? How is it prepared? Write the engineering application of PVC. (b) Write preparation, properties and uses of phenol formaldehyde resins. [8+8] 6. Write a note on lubricants with special reference to their classification, mode of action, examples and applications. [16] 7. (a) What are the functions of lubricants? (b) Write a note on extreme pressure lubrication. [8+8] 8. (a) Define a Fuel? How chemical fuels are classified and give examples for each. (b) What is meant by Calorific value of a fuel? Define calorie and kilocalorie. [10+6]
I B.Tech Semester Supplimentary Examinations, June 2009 ENGINEERING CHEMISTRY
( Common to Mechanical Engineering, Mechatronics, Production Engineering and Automobile Engineering)
Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆ 1. (a) What is hardness of water? How do you express the hardness? What are the units to express the hardness? (b) Give an account of the disadvantages of hard water. [8+8] 2. (a) What is meant by desalination? What is its significance? (b) Explain the different methods used for the desalination of brackish water. [4+12] 3. (a) Give an account of the various factors which influence the rate of corrosion. (b) Write a brief account on pilling-bedworth rule. [8+8] 4. Explain the following terms: [16] (a) Drying oil (b) Thinners (c) Driers (d) Fillers. 5. (a) What is Nylon and how is it prepared? (b) Explain any one of the mechanism of addition polymerization. Using a suitable example. (c) Describe the important uses of PVC. [6+6+4] 6. (a) Define flash and fire points. (b) Discuss the important functions of lubricants. [16] 7. (a) What is meant by the term lubrication ? (b) Define the following: i. lubricant ii. Friction iii. Seizure. (c) What is surface roughness, surface attraction and surface energy? [2+8+6] 8. (a) What is Transportation theory? Explain? (b) What is coal? How it is formed? (c) Explain the classification of coal. [3+4+9]
B.E/B.TECH DEGREE EXAMINATION, JANUARY 2010
FIRST SEMESTER
ENGINEERING CHEMISTRY-I
(REGULATION 2008)
PART A (10X2=20 MARKS)
1. Calculate the hardness of a water sample containing 2.4 mg of calcium chloride in 500 ml of
water?
2. What is Calgon?how does it function in water treatment?
3. Why thermosetting plastics can not be remoulded?.
4. What is the role of Sulphur in the vulcanization of rubber?
5. Compare absorption and adsorption.
6. Mention any four applications of adsorption.
7. Furnish the sequence of reactions in proton cycle nuclear fusion.
8. Give any two advantages of alkaline battery over dry cell.
9. Define refractoriness of a refractory.
10. What are nano materials? Mention any two of their characteristic properties.
PART B-(5 X 16=80)
11.i. How is temporary hardness of water estimated by EDTA method?
ii. What are the requirements of potable water? How will you purify water for drinking
purpose?.
Or
12.i.. What are ion exchange resins? How are they useful in removing hardness of water?
ii. What is desalination? With a neat diagram, describe the 'reverse osmosis' method for the
desalination of brackish water.
13.i. how are the following polymers prepared?
1. Teflon
2. Polystyrene
3. PET
4. Nylon 6, 6
ii. Explain the mechanism of free radical addition polymerization.
Or
14.i. What is natural rubber? Explain why natural rubber needs vulcanization. How is it carried
out?
ii. What are composites? Give the preparation and uses of glass fiber reinforced composites
and carbon fiber reinforced composites.
15.i. Compare physisorption and chemisorption.
ii. Adsorption of gases on solids is greatly influenced by temperature,pressure and nature of
the adsorbent and adsorbate.justify.
Or
16.i. Describe the role of adsorbents in catalysis with examples.
ii. How is ion exchange adsorption useful in demineralization of water? Explain.
17.i. Explain with a neat diagram the parts and functions of a nuclear reactor.
ii. Write a note on photovoltaic cell.
Or
18.i. Explain the working of hydrogen oxygen fuel cell.
ii. Write a short note on lithium batteries.
19.i. How are alumina and carborundum manufactured?.
ii. What are refractories?how are they classified? .
Or
20.i. What are fluid and boundary lubrication? Explain.
ii. What are carbon nano tubes? Explain any three of their important applications?
I B.Tech Supplimentary Examinations, Aug/Sep 2008 ENGINEERING CHEMISTRY
( Common to Mechanical Engineering, Mechatronics, Production Engineering and Automobile Engineering)
Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆ 1. (a) What is hardness of water? How do you express the hardness? What are the units to express the hardness? (b) Give an account of the disadvantages of hard water. [8+8] 2. Write short notes on the following: [16] (a) Carry over (b) Ion-exchange process. 3. (a) Give an account of the various factors which influence the rate of corrosion. (b) Write a brief account on pilling-bedworth rule. [8+8] 4. Write note on: [16] (a) Phosphate coatings (b) Chemical oxide coatings (c) Anodized coatings. 5. (a) Identify the thermo sets and thermoplastics among the following: i. PVC. ii. Polyethylene. iii. Silicone. iv. Polyester fibre. v. Bakelite. (b) What is bakelite? How is it manufactured and mention its uses? [5+11] 6. Write a note on lubricants with special reference to their classification, mode of action, examples and applications. [16] 7. Describe the various types of lubrication. [16] 8. (a) Describe the ultimate analysis of coal and its significance. (b) Describe the manufacture of coke by Beahive oven method with a neat dia- gram. [8+8]
⋆ ⋆ ⋆ ⋆ ⋆
I B.Tech Supplimentary Examinations, Aug/Sep 2008 ENGINEERING CHEMISTRY
( Common to Mechanical Engineering, Mechatronics, Production Engineering and Automobile Engineering)
Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks 1. Write a brief account on the following: (a) Alkalinity of water (b) Complexometric method of estimation of hardness of water. [8+8] 2. (a) With the help of a neat diagram, explain the reverse osmosis method for desalinationof brackish water. (b) Write a brief account on boiler corrosion. [8+8] 3. Write short notes on: (a) Galvonic corrosion (b) Concentration cell corrosion. [8+8] 4. Explain different types of Metallic Coatings. [16] 5. (a) What are the draw backs of raw rubber? How are its properties improved? (b) How is Buna - S Rubber prepared? Write its uses. [8+8] 6. Write a note on lubricants with special reference to their classification, mode of action, examples and applications. [16] 7. Discuss the various types of liquid lubricants. [16] 8. A petrol sample contains 84% carbon and 16% Hydrogen by weight. Its flue gas composition by volume is CO2 = 12.1%, CO = 1.0%, Oxygen = 1.4% and N2 = 85.5%. Calculate (a) minimum air for complete combustion of 1.0 kg of petrol. (b) Actual air supplied per kg of petrol and (c) the C.V of the petrol sample. [16]
⋆ ⋆ ⋆ ⋆ ⋆
I B.Tech Supplimentary Examinations, Aug/Sep 2008 ENGINEERING CHEMISTRY
( Common to Mechanical Engineering, Mechatronics, Production Engineering and Automobile Engineering)
Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆ 1. Write a brief account on the following: (a) Treatment of water for drinking purpose. (b) Determination of chlorides in water. [8+8] 2. (a) What is meant by desalination? What is its significance?
(b) Explain the different methods used for the desalination of brackish water. [4+12] 3. Justify the following statements by giving suitable examples. (a) Electrochemical series gives a basis for the prediction of the process of corro- sion. (b) Design and material selection to help to control metallic corrosion. [8+8] 4. Explain the following terms: [16] (a) Drying oil (b) Thinners (c) Driers (d) Fillers. 5. (a) Identify the thermo sets and thermoplastics among the following: i. PVC. ii. Polyethylene. iii. Silicone. iv. Polyester fibre. v. Bakelite. (b) What is bakelite? How is it manufactured and mention its uses? [5+11] 6. Write short notes on the following properties of lubricants. (a) Pour point (b) Fire point (c) Neutralization number (d) Emulsification. [4x4] 7. (a) What are the functions of lubricants? (b) Write a note on extreme pressure lubrication. [8+8] 8. (a) Define a Fuel? How chemical fuels are classified and give examples for each. (b) What is meant by Calorific value of a fuel? Define calorie and kilocalorie. [10+6]
⋆ ⋆ ⋆ ⋆ ⋆
I B.Tech Supplimentary Examinations, Aug/Sep 2008 ENGINEERING CHEMISTRY
( Common to Mechanical Engineering, Mechatronics, Production Engineering and Automobile Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆ 1. (a) Explain the different sources of water and their composition. (b) With the help of the relevant chemical equations give an account of the effect of water on rocks and minerals. [8+8] 2. (a) Explain the method of softening of water by hot lime soda process. (b) A sample of water contains the following dissolved impurities CaCO3 =100 ppm, Mg(HCO3)2 = 14.6 ppm, CaSO4 = 13.6 ppm, MgCl2 = 9.5 ppm, Al2 (SO4)3 =34.2ppm and silica = 9 ppm. Calculate the amount of lime and soda required for the purification of 1000 litres of water. [8+8] 3. (a) What is corrosion? What are the units in which it is expressed? How is it different from errosion? (b) Explain the mechanism of electrochemical corrosion. [8+8] 4. Describe the process of dipping methods. [16] 5. (a) Describe the preparation properties and engineering uses of polyethylene. (b) What is meant by Fabrication of plastics? Mention the different fabrication techniques. [8+8] 6. Explain the following two theories for the mechanism of the lubricants. (a) Boundary lubrication (b) Extreme pressure lubrication. [8+8] 7. (a) What are the functions of lubricants? (b) Write a note on extreme pressure lubrication. [8+8] 8. (a) Define a Fuel? How chemical fuels are classified and give examples for each. (b) What is meant by Calorific value of a fuel? Define calorie and kilocalorie. [10+6]
⋆ ⋆ ⋆ ⋆ ⋆
I B.Tech Supplimentary Examinations, Aug/Sep 2007 ENGINEERING CHEMISTRY
( Common to Mechanical Engineering, Mechatronics, Production Engineering and Automobile Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆ 1. Write a brief account on the following: (a) Treatment of water for drinking purpose. (b) Determination of chlorides in water. [8+8] 2. (a) What is meant by desalination? What is its significance? (b) Explain the different methods used for the desalination of brackish water. [4+12] 3. (a) What are electrochemical series? How are they useful in determining the rate of corrosion? (b) How do you differentiate electrochemical series from galvanic series? [8+8] 4. (a) What is Sheradizing? Explain and discuss its applications. (b) Write note colirizing and chromizing. [8+8] 5. (a) Write a note on properties and uses of Teflon. (b) Differentiate the Natural Polymer and synthetic polymer. (c) Write a note on silicone rubbers. [4+6+6] 6. Explain the following two theories for the mechanism of the lubricants. (a) Boundary lubrication (b) Extreme pressure lubrication. [8+8] 7. (a) Discuss solid lubricants. (b) Explain the mechanism of thin-film lubrication. [8+8] 8. (a) Define a Fuel? How chemical fuels are classified and give examples for each. (b) What is meant by Calorific value of a fuel? Define calorie and kilocalorie. [10+6]
⋆ ⋆ ⋆ ⋆ ⋆ 1 of 1
I B.Tech Supplimentary Examinations, Aug/Sep 2007 ENGINEERING CHEMISTRY
( Common to Mechanical Engineering, Mechatronics, Production Engineering and Automobile Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆ 1. (a) What is hardness of water? How do you express the hardness? What are the units to express the hardness? (b) Give an account of the disadvantages of hard water. [8+8] 2. Compare the following processes. (a) Permutit process with lime soda process. (b) Phosphate conditioning with calgon conditioning. [16] 3. Explain the process of wet corrosion by evolution of hydrogen and absorption of oxygen. [16] 4. Differentiate the following with suitable examples. [16] (a) Paints from varnishes (b) Drying oils from non drying oils. 5. (a) Write the repeat unit in Bakelite, PVC and Nylon? (b) Mention any two important compounding ingredients of rubber. (c) Write a note on Silicones. [5+6+5] 6. Write a note on lubricants with special reference to their classification, mode of action, examples and applications. [16] 7. Describe the various types of lubrication. [16] 8. (a) Define a Fuel? How chemical fuels are classified and give examples for each. (b) What is meant by Calorific value of a fuel? Define calorie and kilocalorie. [10+6]
⋆ ⋆ ⋆ ⋆ ⋆
I B.Tech Supplimentary Examinations, Aug/Sep 2007 ENGINEERING CHEMISTRY
( Common to Mechanical Engineering, Mechatronics, Production Engineering and Automobile Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆ 1. (a) What is the cause of hardness of water? How is the hardness of water ex- pressed? (b) Explain the soap titration method for the estimation of total hardness of water. (c) Calclulate the temporary hardness of water from the following data by the soap titration method, when 100 ml of the water sample is titrated with soap solution. Leather factor = 0.6 ml soap solution Total hardness = 18.6 ml soap solution Permanent hardness = 6 ml of soap solution. Standard hardwater (400 mg/l of CaCO3) = 36 ml. [4+6+6] 2. (a) What is meant by desalination? What is its significance? (b) Explain the different methods used for the desalination of brackish water. [4+12] 3. Justify the following statements by giving suitable examples. (a) Electrochemical series gives a basis for the prediction of the process of corro- sion. (b) Design and material selection help to control metallic corrosion. [8+8] 4. Explain the following terms: [16] (a) Drying oil (b) Thinners (c) Driers (d) Fillers. 5. (a) Discuss the compounding of plastics? (b) Explain the procedures used in the processing of Natural rubber. (c) Write a note on urea formaldehyde resins. [5+5+6] 6. (a) Define flash and fire points. (b) Discuss the important functions of lubricants. [16] 7. How to select lubricants for the following: [16] (a) cutting tools (b) I.C engines (c) steam engines (d) steam turbines (e) Gears. 8. (a) Define a Fuel? How chemical fuels are classified and give examples for each. (b) What is meant by Calorific value of a fuel? Define calorie and kilocalorie. [10+6]
⋆ ⋆ ⋆ ⋆ ⋆
I B.Tech Supplimentary Examinations, Aug/Sep 2007 ENGINEERING CHEMISTRY
( Common to Mechanical Engineering, Mechatronics, Production Engineering and Automobile Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks
⋆ ⋆ ⋆ ⋆ ⋆ 1. (a) What is meant by break point chlorination? What is its significance and advantages? (b) Explain the sedimentation process for the treatment of muncipal water. [8+8] 2. Write short notes on the following: [16] (a) Carry over (b) Ion-exchange process. 3. (a) What is corrosion? What are the units in which it is expressed? How is it different from errosion? (b) Explain the mechanism of electrochemical corrosion. [8+8] 4. Explain different types of Metallic Coatings. [16] 5. (a) How is PVC prepared and what are its uses? (b) Write down the differences between compression and injection moulding tech- niques. (c) How is Thiokol prepared? Mention its uses. [4+6+6] 6. Write a note on lubricants with special reference to their classification, mode of action, examples and applications. [16] 7. How to select lubricants for the following: [16] (a) cutting tools (b) I.C engines (c) steam engines (d) steam turbines (e) Gears. 8. (a) Explain the recovery of by-product from ‘Coke oven gas’ (b) Give the comparison between solid, liquid and gaseous fuels. [8+8]
⋆