e.g.s. pillay engineering college (an …coe.egspec.org/ct12017/pdf/17ch103 -water vtechnology and...

E.G.S. PILLAY ENGINEERING COLLEGE (An Autonomous Institution, Affiliated to Anna University, Chennai)

Nagore Post, Nagapattinam – 611 002, Tamilnadu.

Rev.0 COE/2017/QB

1701CH103 WATER VTECHNOLOGY AND GREEN CHEMISTRY

Academic Year : 2017-2018 Question Bank

Programme : B.E – CIVIL

Year / Semester : I / I Course Coordinator:

Course Objectives

Course Outcomes:

1. Imparting knowledge on the principles of water characterization, treatment methods and industrial applications

2. Understanding the principles and application of electrochemistry and corrosion science.

3. Basic information and application of polymer chemistry, nanotechnology and analytical techniques

On completion of the course, students will be able to

CO1. Understand the chemistry of water and its industrial &

domestic application (K2).

CO2. Utilization of electrochemistry principles in corrosion control and industrial application (K2)

CO3. Differentiate the polymers and materials used in day to

day life based on its source, properties and applications(K2)

CO4. Identify the applications of nanotechnology and analytical methods for the estimation of elements (K2)

PART – A ( 2 Mark Questions With Key)

S.No Questions Mark COs BTL

UNIT I- WATER TECHNOLOGY

1 Define the term hardness of water

CO1 (K1)

Hardness is the property or characteristics of water , Which does not

produce lather with soap. 2

CO1 (K1)

2 Compare temporary and permanent hardness in water.

CO1 (K2)

Temporary hardness It is due to carbonates and bicarbonates of calcium and

magnesium.

It can be removed by boiling the water.

Permanent hardness

It is due to chlorides and sulphates of calcium and

magnesium.

. It can not be removed by boiling the water.

2

CO1

3 Calgon conditioning is advantageous over phosphate conditioning- Why.

CO1 (K2)

Calgon is Sodium hexa meta phosphate Na2 (Na4 (PO3)6). 2. 1

CO1



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This substance interacts with calcium ions foming a highly soluble

complex and thus 3. the precipitation of scale forming salt.

2CaSO4 + Na2 (Na4 (PO3)6 Na2 (Ca2 (PO3)6) + 2Na2SO4

1

4 What is meant by Phosphate Conditioning?

CO1 (K1)

Scale formation can be avoided by adding sodium phosphate. It is used high pressure boilers.The phosphate react with Ca2+ and Mg2+ salts to give soft sludges Ca and Mg phosphates.

3CaSO4 +2Na3PO4 Ca3 (PO4)2 +3Na2SO4

2 CO1

5 What are the disadvantages of scale formation?

CO1 (K1)

Scale act as thermal insulators. It decreases the efficiency of boiler. Any crack developed on the scale, leads to explosion.

1

1

CO1

6 What are boiler compounds? Give two examples.

CO1 (K1)

Scale forming substances can be removed by adding chemicalsdirectly to the boiler. These chemicals are called boiler compounds.Examples: Sodium carbonate and sodium phosphate

i) CaSO4 +Na2CO3 CaCO3 +Na2SO4

(ii)3CaSO4 +2Na3PO4 Ca3 (PO4)2 +3Na2SO4

2 CO1

7 Distinguish between hard and soft water

CO1 (K2)

Hard water:

(i) Hard water does not produce lather with soap solution.

(ii)It gives wine red color with EBT indicator Soft water:

(i)Soft water produces very good lather with soap solution. (ii)It does not give color with EBT indicator.

1

1

CO1

8 List two disadwantages of using hardwater in boilers.

CO1 (K1)

(i).Formation of deposits (Scale and sludge) in boilers. 2 CO1



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(ii).Priming and foaming (carry over).

(iii). Caustic embrittlement.

(iv).Boiler corrosion.

9 What is meant by priming and foaming?

CO1 (K1)

Priming is the process of production of wet steam. Foaming is the formation of stable bubbles above the surface of water.

2 CO1

10 Name the gases dissolved in water that cause corrosion?

CO1 (K1)

(i).Dissolved oxygen(DO)

(ii). Dissolved Carbon dioxide(CO2)

2 CO1

11 Distinguish between hard water and soft water.

CO1 (K2)

Hard water Soft water

(i)Hard water does not produce lather with

soap solution.

(i)Soft water produces very good

lather with soap solution.

(ii)It give wine red colour with EBT

indicator.

(ii)It does not give colour with

EBT.

1

1

CO1

12 What is meant by softening or conditioning of water? How is it carried out?

CO1 (K1)

The process of removing hardness producing salts from water is known as

softening (or) conditioning of water.

Softening of water can be done in two methods

1. External conditioning.

2. Internal conditioning.

2 CO1

13 What is blow-down operation?

CO1 (K1)

Blow-down operation is a process of removing a portion of concentrated

water by fresh water frequently from the boiler during steam production.

2 CO1

14 What are the requirements of boiler feed water?

CO1 (K1)



Rev.0 COE/2017/QB

2 CO1

15 Soft water is not DM water whereas DM water is soft water- Justify

CO1 (K2)

The soft water, produced by lime-soda and zeolite processes, does not

contain hardness producing Ca2+

and Mg2+

ions, but it will contain other ions like

Na+, K

+,SO4

2-, Cl

- etc., On the other hand demineralised water does not contain

both anions and cations.

2 CO1

UNIT –II CORROSION AND PROTECTIVE COATING

1 State Pilling-Bedworth rule. CO2 (K1)

According to Pilling – Bedworth rule, if the volume of the oxide layer less than the volume of the metal, the oxide layer is porous and non-protective. 1. Example: Oxides of alkali and alkaline earth metals such as Na, Mg,

Ca, etc., 2. On the other hand, if the volume of the oxide layer is great volume of the metal, the oxide layer is non- porous and protective. 3.

Example: Oxides of heavy metals such as Pb, Sn, etc,

2 CO2 (K1)

2 Why does Mg corrode faster than iron?

CO2

(K2)

Galvanic corrosion occurs. Mg (more active or higher in emf series) dissolves in preference to iron(less active metal) i.e Mg acts anode and undergoes corrosion and Fe acts as cathode. It can be prevented by providing insulation between the two metals.

2 CO2

3 Bolt and nut of same metal is preferred in practice. Why? CO2 (K2)

It is preferred in practice, because galvanic corrosion is avoided due to homogeneous metals (no anodic and cathodic part)

2 CO2 (K2)

4 What is pitting corrosion? CO2 (K1)

Pitting is a localized attack, resulting in the formation of a hole around which the metal is relatively unattacked. Example: Ex: Metal area covered by a drop of water, sand, dust etc

2 CO2 (K1)



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5 List the differences between chemical corrosion and electrochemical

corrosion.

CO2 (K2)

Chemical corrosion Electrochemical corrosion

It occurs dry state

It occurs in the presence of moisture or

electrolyte

It follows adsorption

mechanism It follows electrochemical reaction

Corrosion product accumulate

on the same spot, where

corrosion occurs.

Corrosion occurs at anode while

products gather at cathode

2 CO2 (K2)

6 What are the advantages of electroless plating over electroplating.

CO2 (K1)

i)No electricity is required

ii) Electroless plating on insulators (like plastics,glass) and semiconductors

can be easily carried out.

iii)Complicated parts can also be plated uniformly.

iv) Electroless coating possesses good mechanical, chemical, and magnetic

properties.

2 CO2 (K1)

7 What are the requisites of a good paint? (K1) CO2 (K1)

It should spread easily on the metal surface

It should not crack on drying

The colour of the paint should be stable

It should be corrosion and water resistant

2 CO2 (K1)

8 What is differential aeration corrosion? CO2 (K1)

Differential aeration is nothing but two different concentration of air on a metal surface.

2 CO2 (K1)

9 What is galvanizing? CO2 (K1)

The process of coating molten zinc over the base metal is known as

galvanizing.

2 CO2 (K1)

10 What is hydrogen embrittlement? (K1)



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The process of formation of cracks and blisters on the metal

surface due to high pressure of hydrogen gas is called hydrogen embrittlement.

2 CO2 (K1)

11 Zinc is more readily corroded when coupled with copper than with lead why? CO2 (K2)

Zinc is anodic to Cu and Pb. When zinc is (E0= -0.76V) is coupled

with copper (E0= + 0.34V) zinc is more readily corroded, because the

difference in their position in emf series is more. Also Cu has (+)ve

reduction potential. But if Zn is coupled with lead (E0= -0.13V) rate

corrosion is less because the difference in their position in emf series is

less. Also Pb has (-) ve reduction potential.

2 CO2 (K2)

12 What is water line corrosion? CO2 (K1)

This type of corrosion occurs when a metal is exposed to carying concentration of oxygen or any electrolyte on the surface of the base metal. Here the metal above the water is more aerated and becomes cathodic, the part below the water is less aerated and becomes anodic. Example:

Metals partially immersed in a water (or) conducting solution

2 CO2 (K1)

13 What type of corrosion will occur to a Zn – Fe couple immersed in an

electrolyte? How can it be prevented?

CO2 (K2)

Galvanic corrosion occurs. Zinc (more active or higher in emf series) dissolves in preference to iron(less active metal) i.e Zn acts anode and undergoes corrosion and Fe acts as cathode. It can be prevented by providing insulation between the two metals.

2 CO2 (K2)

14 What is electroplating? CO2 (K1)

Electroplating is the process in which the coating metal is deposited on the base metal by passing a direct current through an electrolytic solution containing the soluble salt of the coating metal

2 CO2 (K1)

15 What is galvanic corrosion? CO2 (K1)

When two different metals are in contact with each other in presence of an aqueous solution or moisture, galvanic corrosion occurs.

2 CO2

UNIT III – POLYMER AND NANO TECHNOLOGY

1 Distinguish between thermoplastic and thermosetting plastics. CO3 (K2)

Thermo plastics: Thermosetting plastics

Formed by addition polymerization Formed by condensation polymerisation

Consists of long chain polymers consists of three dimensional network

Held together by weak vander waals forces held together by strong covalent bond

Weak,soft and less brittle Strong, hard and more brittle

2 CO3 (K2)

2 Define polymer & monomer?

CO3 (K1)



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Polymers are macro molecules formed by the repeated linking of large number of small

molecules. Monomer is a micro molecule which combines with each other to form a

polymer.

2 CO3 (K1)

3 Define functionality of a polymer CO3 (K1)

The number of bonding sites or reactive sites or functional groups present in a monomer. 2 CO3 (K1)

4 Define Polymerisation CO3 (K1)

Large number of small molecules combines to give a big molecule with or without

elimination of small molecules like water.

2 CO3 (K1)

5 Define Degree of polymerisation CO3 (K1)

The number of repeating units in a polymer chain. 2 CO3 (K1)

6 Classify the polymers on the basis of their tactility? CO3 (K1)

i) Isotactic Polymer ii) Syndiotactic Polymer iii) Atactic Polymer

2 CO3 (K1)

7 What is meant by copolymerisation? CO4 (K1)

It is the joint copolymerization in which two (or) more different monomers combine to

give a polymer. High molecular weight polymers obtained by copolymerization.

2 CO4 (K1)

8 What is meant by condensation polymerisation CO4 (K1)

It is the reaction between simple polar groups containing monomers with the formation of

polymer and elimination of small molecules like H2O, HCl, etc.,

2 CO4

9 What is is nano-chemistry? CO4 (K1)

Nano-chemistry is a branch of nano-science, which deals with the chemical applications

of nanomaterials. It is also includes the study of synthesis and characterization of

nanomaterials.

2 CO4 (K1)

10 What are nano-wires? CO4 (K1)

Nano-wire is a material having an aspect ratio i.e., length to width ratio greater than 20.

Nano-wires are also referred to as “quantum wires”.

2 CO4 (K1)

11 What is meant by Quantum dots?

In the language of materials science, nanoscale semiconductor materials tightly confine

either electrons or electron holes. Quantum dots are also sometimes referred to

as artificial atoms, a term that emphasizes that a quantum dot is a single object

with bound, discrete electronic states, as is the case with naturally

occurring atoms or molecules.

2

https://en.wikipedia.org/wiki/Materials_science

https://en.wikipedia.org/wiki/Electron_holes

https://en.wikipedia.org/wiki/Bound_state

https://en.wikipedia.org/wiki/Atom

https://en.wikipedia.org/wiki/Molecule



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12 What is meant by Crystal engineering

Crystal engineering is the design and synthesis of molecular solid state structures with

desired properties, based on an understanding and use of intermolecular interactions. The

two main strategies currently in use for crystal engineering are based on hydrogen

bonding and coordination bonding. These may be understood with key concepts such as

the supramolecular synthon and the secondary building unit.

2

13 What are nano rods?

Nanorod is two dimentional cylindrical soild material having an aspect ratio i.e. length to

width ratio less than 20

e.g. Zinc oxide,Cadmium sulphide,Gallium nitride. nano rods

2

14 What are CNT’s ? How is it classified?

CNT’s are Carbon Nano Tubes. It is classified SWCNT&MWCNT

SWCNT- Single Walled Carbon Nano tube

MWCNT- Multi Walled Carbon Nano Tube.

2

15 What is meant by magic number?

Magic number is the number of atoms present in the clusters of critical sizes with the

higher stability.

2

UNIT IV –ENGINEERING MATERIALS

1 Define Abrasives

CO3 (K1)

Abrasives are hard substances used for polishing, shaping, grinding

operations.

e.g. Talc and Diamond

2

CO3 (K1)

2 Give two examples for natural abrasives and synthetic abrasives. CO3 (K1)

Natural abrasives- Diamond, quartz, corundum, emery.

Synthetic abrasives-1.Carborundum 2.Norbide

2

CO3 (K1)

3 Define refractories.

CO3 (K1)

It is the ability of a material to withstand very high temperature

without softening or deformation under particular service

condition. It is expressed in terms of pyrometric cone equivalent.

2

CO3 (K1)

4 What is hardness of an abrasive? What is its units?

.

CO3 (K1)

https://en.wikipedia.org/wiki/Intermolecular_force

https://en.wikipedia.org/wiki/Hydrogen_bond



https://en.wikipedia.org/wiki/Synthon



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It is the ability of an abrasive to grind or scratch away other materials.The

harder the abrasive quicker will be its abrading action. Hardness of the

abrasive is measured on Moh’s scale

2 CO3

5 What is Moh’s scale of abrasives?

CO3 (K1)

Moh’s scale is a scale, in which common abrasives are

arranged in the order of their increase in hardness.

Any two examples from the table

Name of the

abrasives

Moh’s number

(or) hardness

Talc 1

Gypsum 2

Calcite 3

Fluorite 4

Apatite 5

Feldspar 6

Quartz 7

Topaz 8

Corundum 9

Diamond 10

1

1

CO3

6 Define thermal spalling

CO3 (K1)

Thermal spalling is the property of breaking, cracking or peeling

off a refractory material under high temperature.

2 CO3



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7 What are the raw materials used for the manufacture of cement?

CO3 (K1)

Raw materials :

(i) Calcareous materials, CaO Ex: Limestone, chalk.

(ii) Argillaceous materials, Al2O3 and SiO2 Ex: clay, slate etc

(iii) Powdered coal (or) fuel oil.

(iv) Gypsum (CaSO4.2H2O)

2

CO3

8 Define the term setting and hardening of cement?

CO3 (K1)

Setting : It is defined as the stiffening of the original plastic

mass,due to the formation of tobermonite gel.

Hardening: It is defined as the development of strength due to

formation of crystals.

2 CO3

9 What is hydrophobic cement?.

CO3 (K1)

Hydrophobic cement or Water Proof Cement:

It is obtained by adding water proofing agents like calcium

stearate and gypsum with tannic acid to ordinary Portland cement during

grinding.

Functions of water- Proof cement:

(i) To make concrete impervious to water under pressure.

(ii) To resist the adsorption of water.

2 CO3



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10 What is white cement? CO3 (K1)

It is obtained by heating the raw materials free from iron oxides. It is white in

color due to the absence of ferric oxide. It issued for making tiles, mosaic works

with some coloring agents like yellow ochre, Venetian red etc. It is used for

repairing and joining marble pillars and blocks.

2 CO3

11 What is meant by dimensional stability?

CO3 (K1)

Dimensional stability

Resistance of refractory to any volume change when exposed to

high temperature over a prolonged time. Refractories may undergo

reversible or irreversible dimensional changes. A good refractory

should show minimum level of reversible dimensional changes with

temperature.

1

1

CO3

12 What is emery?

CO3 (K1)

It is a fine – grained, opaque mineral and black in colour.

It consists of 55-75% crystalline alumina, 20-40%

magnesite and 12% other minernals. Its hardness is 8 on

Moh’s scale.

2 CO3

13 What is meant by flash set?

.

CO3 (K1)

When the cement is mixed with water ,at first ,hydration of tricalcium

aluminate takes place rapidly and the past become quite rigid within a

short time which is known as initial set or flash set

2 CO3

14 Mention the characteristics or requisites of a good refractory.

CO3 (K1)

(i) It should be infusible at the operating temperatures

(ii) It should be chemically inert towards the corrosive gases,

metallic slags and liquids.

2 CO3



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(iii) It should resist the abrading action of flue gases, flames etc.

(iv) It should not crack and suffer loss in size at the operating

temperatures.

15 What is cement?

CO3 (K1)

Cement is defined as an inorganic binding material possessing

adhesive and cohesive properties and capable of bonding materials

like stones, bricks, building blocks etc.

2 CO3

UNIT V - INSTRUMENTAL TECHNIQUES OF CHEMICAL ANALYSIS

1 State Beer - Lamberts law. CO4 (K1)

“When a beam of monochromatic radiation is passed through a homogenous absorbing

solution, the decrease in the intensity of the radiation dI with the thickness of the

absorbing solution dx is directly proportional to the intensity of the incident radiation I as

well as the concentration of the solution C.

2 CO4 (K1)

2 State Grothus –Draper Law CO4 (K1)

This law states that “when light falls on any substance, only the fraction of incident light

which is absorbed by the substance can bring about a chemical change”. It is also called

the principle of photochemical activation.

2 CO4 (K1)

3 Define Quantum yield or Quantum Efficiency. CO4 (K1)

Ф = No. of molecules reacting in a given time

No. of quanta (photons) of light absorbed in the same time

2 CO4 (K1)

4 Write any two reasons for high quantum yield. CO4 (K2)

The absorption of radiation in the primary step produces atoms or free radicals, which

initiates a series of chain reactions.

1 CO4 (K2)

The active molecules produced by primary absorption may collide with other molecules,

thereby activating them, which in turn further activate other reacting molecules

1 CO4 (K2)



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5 What is a photosensitizer? Give an example CO4 (K1)

substance which absorbs light and induces a photochemical reaction without undergoing

chemical reaction is known as photosensitiser

1 CO4 (K1)

Atomic Photosensitisers – Mercury, cadmium, Zinc

Molecular Photosensitisers – Benzophenone, Sulphur dioxide, Uranyl sulphate.

1 CO4

6 What is quenching? CO4 (K1)

Foreign substance (sensitizer), absorbs light and gets excited. When the excited foreign

substance collides with another substance it gets converted in to some other product due

to the transfer of its energy

2 CO4 (K1)

7 What are chromophores? Give an example.

CO4 (K1)

One or more unsaturated linkage is responsible for the colour of the compound eg: C=C,

-NO , -N=N

2 CO4 (K1)

8 What if finger print region? CO4 (K1)

The vibration spectral region at 1400 – 700 cm -1 gives very rich and intense absorption

bands which is unique for each molecule. This region is termed as Finger Print Region.

2 K1 (K1)

9 Write the keto enal tautomerism of ethyl acetoacetate CO4 (K1)

keto form λ Max.275 nm, Enol form λ Max. 244 nm

2 CO4 (K1)

10 Calculate the number of modes of (IR) vibration for the following molecules.1. Non-linear (CH4)

2. Linear molecule(CO2)

CO4 (K2)

(a) CH4 (Non linear molecule) = 3N- 6 = (3 x 5) – 6 = 9

(b) CO2 (linear molecule) = 3N- 5 = (3 x 3) – 5 = 4

2 K1 (K2)

11 Mention three applications of UV-Visible Spectroscopy CO4 (K1)

concentration of unknown solution ,identification of aromatic compounds ,detecting

impurities

2 CO4 (K1)

12 Define the term – Bathochromic shift, Hypsochromic shift CO4 (K1)

Bathochromic shift: shifting of absorption band towards a longer wavelength.

Hypsochromic shift: shifting of absorption band towards a shorter wavelength.

2 CO4 (K1)



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13 Write any two limitations of Beer-Lamberts law? CO4 (K1)

1. Radiation used is monochromatic.

2. Applicable only for dilute solutions.

3. Temperature of the system should not be allowed to vary to a larger extent.

2 CO4 (K1)

14 What is the relation between wavelength, frequency and wave number? CO4 (K1)

1/λ = υ = υ/c

2 CO4 (K1)

15 What are the factors which affect the absorbance of the photons by a molecule?

CO4 (K1)

1.The nature of the absorbing molecules

2. The concentration of the molecules

3. Path length of radiation

2 CO4 (K1)

PART – B (12 Mark Questions with Key)

S.

N

o

Questions Mark COs BTL

UNIT I –WATER TECHNOLOGY

1 How will you protect boiler from corrosion. 12 CO1 (K2)

4

a)Chemical method:

Sodium sulphite, hydrazine are some of the chemicals used for

removing oxygen.

(b)Mechanical de-aeration:

4

4



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Dissolved oxygen can also be removed from water by mechanical

deaeration.

In this process, water is allowed to fall slowly on the perforated

plates fitted inside the tower.

The sides of the tower are heated, and a vacuum pump is also

attached to it.

The high temperature and low pressure produced inside the tower

reduce the dissolved oxygen content of the water.

Mechanical de-aeration of water

(c)Removal of dissolved Carbon dioxide:

Carbon dioxide can be removed from water by adding a calculated

amount of NH4OH into water.

Carbon dioxide along with oxygen can also be removed mechanically by

de-aeration method.

(d) Removal of acids:

Corrosion by acids can be avoided by the addition of alkali to the boiler

water.

2 How can the effect of caustic embrittlement in boiler be resolved? 12

CO1 (K2)

Caustic embrittlement means intercrystalline cracking of boiler

metal.

Boiler water usually contains a small proportion of Na2CO3. In

high pressure boilers this Na2CO3 undergoes decomposition to

give NaOH.

3

5



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This NaOH flows into the minute hair cracks and crevices, usually

present on the boiler material, by capillary action and dissolves

the surrounding area of iron as sodium ferroate.

This causes embrittlement of boiler parts, particularly stressed

parts like bends, joints, rivets, etc., causing even failure of the

boiler.

Prevention:

Caustic embrittlement can be prevented by

(i) Using sodium phosphate as softening agent instead of sodium

carbonate.

(ii) By adding tannin, lignin to the boiler water, this blocks the

cracks.

4

3 Identify the problems created in boilers if priming and foaming takes

place 12

CO1 (K2)

(a)Priming:

Priming is the process of production of wet steam.

3



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Priming is caused by

(i) High steam velocity.

(ii) Very high water level in the boiler.

(iii) Sudden boiling of water.

(iv) Very poor boiler design.

Priming can be controlled by

(i) Good boiler design.

(ii) Using treated water.

(b)Foaming:

The formation of stable bubbles above the surface of water is

called foaming.

Foaming is caused by the

(i) Presence of oil, and grease,

(ii) Presence of finely divided particles.

Foaming can be prevented by

(i) Adding coagulants like sodium aluminate, aluminium

hydroxide,

(ii) Adding anti-foaming agents like synthetic polyamides.

3

3

3

4 Describe the Reverse Osmosis method for desalination of water. 12

CO1 (K2)



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4

Desalination

The process of removing common salt (sodium chloride)

from the water is known as desalination.

Desalination is carried out either by reverse osmosis or

electro dialysis.

Reverse osmosis

When two solutions of different concentrations are separated by a

semi-permeable membrane, solvent (water) flows from a region of

lower concentration to higher concentration. This process is called

osmosis.

The driving force in this phenomenon is called osmotic pressure.

When the solvent flows from higher concentration to lower

concentration through a semi-permeable membrane is called

reverse osmosis.

Thus, in the process of reverse osmosis pure water is separated

from salt water. This process is also known as super-filtration.

The membranes used are cellulose acetate, cellulose butyrate, etc.

Advantages:

(i) The life time of the membrane is high, and it can be replaced

within few minutes.

(ii) It removes ionic as well as non-ionic, colloidal impurities.

(ii) Due to low capital cost, simplicity, low operating, this process is

3

5



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used for converting sea water into drinking water.

5 What are zeolites? How do they function in removing the hardness of

water? 12

CO1 (K2)

4

Zeolites is porous and possess gel like structure, hence it is generally used

for water softening. It is represented by Na2Ze. The sodium ions which are

loosely held in Na2Ze are replaced by Ca2+

and Mg2+

ions present in the

water.

Process

When hard water is passed through a bed of sodium zeolite (Na2Ze),

kept in a cylinder, it exchanges its sodium ions with Ca2+

and Mg2+

ions

present in the hard water to form calcium and magnesium zeolites. The

various reactions taking place during softening process are

CaSO4+ Na2Ze→CaZe+Na2SO4

The softened water is enriched with large amount of sodium salts,

which do not cause any hardness, but cannot be used in boilers.

Regeneration

3

3



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After some time zeolite gets exhausted. The exhausted zeolite is again

regenerated by treating with 10% solution of NaCl.

CaZe+2NaCl→Na2Ze+CaCl2

Advantages of Zeolite process

Water will have only hardness of 1-2 ppm.

No sludge is formed during this process.

Its operation is easy.

Disadvantages of Zeolite process

Turbid water cannot be treated.

Acidic water cannot be treated.

Water containing Fe, Mn cannot be treated

2

6 Explain the following boiler troubles suggesting the remedial methods: (i)

Scale and sludge formation (ii) Priming and foaming. 12

CO1 (K2)

(a)Sludge (b)Scale

2

Sludge (Loose deposit)

If the precipitate is loose and slimy it is called sludge.

Sludges are formed by substances like MgCl2, MgCO3, MgSO4

and CaCl2.

2



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They have greater solubilities in hot water than cold water.

Scale (Hard deposit)

On the other hand, if the precipitate forms hard and adherent

coating on the inner walls of the boiler, it is called scale.

Scales are formed by substances like Ca(HCO3)2,CaSO4 and

Mg(OH)2.

Prevention of scale formation:

They can be removed by using scraper, wire brush etc.

They can be removed by thermal shocks.

By using suitable chemicals like dil.acids.

Priming:

Priming is the process of production of wet steam.

Priming is caused by

(i) High steam velocity.

(ii) Very high water level in the boiler.

(iii) Sudden boiling of water.

(iv) Very poor boiler design.

Priming can be controlled by

(i) Good boiler design.

(ii) Using treated water.

Foaming:

The formation of stable bubbles above the surface of water is

called foaming.

Foaming is caused by the

(i) Presence of oil, and grease,

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(ii) Presence of finely divided particles.

Foaming can be prevented by

(i) Adding coagulants like sodium aluminate, aluminium

hydroxide,

(ii) Adding anti-foaming agents like synthetic polyamides.

UNIT II - CORROSION AND ITS CONTROL

1 Illustrate the mechanism involved in electrochemical corrosion. 12

CO2 (K2)

Wet (or) Electro -Chemical Corrosion

(i) When two dissimilar metals or alloys are in contact with each other in

the presence of an aqueous solution or moisture.

(ii) When a metal is exposed to varying concentration of oxygen or any

electrolyte.

Mechanism of wet corrosion

At anode

In anodic part, oxidation (or) dissolution of metal occurs

At cathode

(a) Acidic environment

If the corrosive environment is acidic, hydrogen evolution occurs at

cathodic part.

(b) Neutral environment

If the corrosive environment is slightly alkaline (or) neutral, hydroxide

ions are formed at cathodic part.

(a) Hydrogen evolution type corrosion

“All metals above hydrogen in the electrochemical series have a tendency

to get dissolved in acidic solution with simultaneous evolution of hydrogen

gas”

Example

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At anode

At cathode

(b) Absorption of oxygen (or) Formation of hydroxide ion type corrosion

The surface of iron is usually, coated with a thin film of iron oxide.

However, if the oxide film grows, some crack will form and anodic areas are

created on the surface while the remaining part acts as cathode

Example

At anode

At cathode

3

2 Describe the factors influencing chemical & electrochemical corrosion.

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The rate of corrosion is mainly depends on

1.Nature of the metal

2.Nature of the environment

Nature of the metal:

(i)Position in emf series

Metals above the hydrogen in emf series get corroded vigorously. Lower

the reduction potential, greater is the rate of corrosion.

When two metals are in electrical contact, the more active metal (or the

metal having high negative reduction potential) undergoes corrosion.

(ii)Relative areas of the anode and cathode

The rate of corrosion will be more, when the cathodic area is larger

(iii)Purity of the metal

The 100% pure metal will not undergo any type of corrosion. Higher the

percentage of impurity, faster is the rate of corrosion of the anodic metal.

(iv)Over voltage or over potential

(v)Nature of the surface film

(vi)Nature of the corrosion product

If the corrosion product is soluble in the corroding medium, the corrosion

rate will be faster.

Nature of the environment

i) Temperature

The rate of corrosion increase with temperature

ii) Humidity

Rate of corrosion will be more, when the humidity in the

environment is high.

iii) Presence of corrosive gases

The acidic gases like CO2,SO2,H2S increases the

electrochemical corrosion.

iv) Presence of suspended particles

It accelerate the electrochemical corrosion

v) Effect of pH The rate of corrosion will be maximum when the corrosive environment is

acidic

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(ie) pH is less than 7.

3 Explain the Electroless Nickel plating 12

CO2 (K2)

Principle Electroless plating is a technique of depositing a noble metal (from its salt solution) on a catalytically active surface of the metal, to be protected, by using suitable reducing agent without using electrical energy.

Step I

Pretreatment and activation of the surface

Step II

Preparation of Plating bath

The plating bath consists of the following ingredients

Step III

Procedure for plating

Nature of the

compound

Name of the

compound

Quantity

(g/l)

Function

Coating solution NiCl2 20 Coating metal

Reducing agent Sodium

hypophosphite

20 Metal ions

reduced

Complexing

agent cum exhaltant

Sodium succinate 15 Improves the

quality

Buffer Sodium Acetate 10 Control of pH

Optimum pH 4.5 - -

Optimum

Temperature

930C - -

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Various reactions

At Cathode

At Anode

Net reaction

Applications

4 Explain differential aeration corrosion and galvanic corrosion with

suitable illustrations. 12

CO2 (K2)

This type of corrosion occurs when a metal is exposed to varying

concentration of oxygen or any electrolyte on the surface of the base metal.

Example

Metals partially immersed in water (or) conducting solution (called

water line corrosion).

If a metal is partially immersed in a conducting solution (Fig. 3.6) the metal

part above the solution is more aerated and hence become cathodic.

On the other hand, the metal part inside the solution is less aerated and

thus, become anodic and suffers corrosion.

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At anode (less aerated part)

At cathode (more aerated part)

Examples for Differential aeration corrosion (a) Pitting or localised corrosion.

(b) Crevice corrosion.

(c) Pipeline corrosion.

(d) Corrosion on wire fence.

(a) Pitting corrosion Pitting is a localised attack, resulting in the formation of a

hole around which the metal is relatively unattacked.

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(b) Crevice corrosion If a crevice between different metallic objects or between metal and non-

metallic material is in contact with liquids, the crevice becomes the anodic

region and suffers corrosion.

This is due to less oxygen in crevice area. The exposed areas act as

cathode

c) Pipeline corrosion Differential aeration corrosion may also occur in different parts of

pipeline.

Buried pipelines or cables passing from one type of soil to another say,

from clay (less aerated) to sand (more aerated) may get corroded due to

differential aeration.

(d) Corrosion on wire-fence Fig. 3.10 shows a wire fence in which the areas where the wires cross

are less aerated than the rest of the fence and hence corrosion occurs at the wire

crossings, which are anodic.



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5 Explain the process of electro deposition taking a suitable example.

12 CO2 (K2)

Process

Various chemical reactions

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At Cathode

At Anode

Characteristics of Copper Plating

6 Explain Dry (or) Chemical corrosion

12 CO2 (K2)

Dry corrosion is due to the attack of metal surfaces by the atmospheric

gases such as oxygen, hydrogen sulphide, sulphur dioxide, nitrogen, etc.

There are 3 main types of dry corrosion.

1. Oxidation corrosion (or) corrosion by oxygen.

2. Corrosion by hydrogen.

3. Liquid-metal corrosion.

1. Oxidation corrosion (or) corrosion by oxygen Oxidation corrosion is brought about by the direct attack of oxygen at low or

high temperatures on metal surface in the absence of moisture.

Mechanism of dry Corrosion

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Nature of oxide film

1. Stable oxide layer Such a film behaves as a protective coating and no further

corrosion can develop.

Example

2. Unstable oxide layer Unstable oxide layer is mainly produced on the surface of noble metals,

which decomposes back into the metal and oxygen.

Example

3. Volatile oxide layer

The oxide layer volatilizes as soon as it is formed, leaving the metal

surface for further corrosion.

Example

4. Protective (or) Non-Protective oxide film (Pilling- Bedworth rule)

According to Pilling – Bedworth rule, if the volume of the

oxide layer formed is less than the volume of the metal, the oxide layer is porous and non-protective.

On the other hand, if the volume of the oxide layer formed is greater than the volume of the metal, the oxide layer is non- porous and protective.

2. Corrosion by hydrogen

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(i) Hydrogen embrittlement (at ordinary temperature)

The process of formation of cracks and blisters on the metal surface, due to

high pressure of hydrogen gas is called hydrogen embrittlement

(ii)Decarburisation (at higher temperature)

The Process of decrease in carbon content in steel is termed as

“decarburisation” of steel.

3. Liquid-metal corrosion

(i) Either dissolution of a solid metal by a liquid metal. (or)

(ii) Liquid metal may penetrate into the solid metal.

UNIT III POLYMER AND NANO TECHNOLOGY

1 Differentiate Thermoplastics and Thermosetting plastics. 12 CO3 (K2)

Thermoplastics Thermosetting plastics

They are formed by addition polymerisation They are formed by condensation

Polymerisation 2

They consist of linear long chain polymers They consist of three-dimensional network

structure 2

All the Polymer chains are held together by

weak Vander Waals forces

All the Polymer chains are linked by strong

covalent bonds 2

They are soluble in organic solvent They are insoluble in organic solvents 2

They can be remoulded and recycled They cannot be remoulded 1

They soften on heating and harden on cooling They do not soften on heating 1

They are weak, soft and less brittle They are strong, hard and more brittle 1

Ex.PVC,PE Ex.Bakelite 1

2 Differentiate Addition polymerization and condensation polymerization. 12 CO3 (K2)

Addition polymerization Condensation polymerization

The monomer should have at least one

multiple bond, E.g., CH2 = CH2 (ethylene) The monomer should have at least two

different functional groups. E.g.,

H2 N(CH2)6 COOH

6-aminohexanoic acid.

2

Monomer adds to give a polymer and no

other by-product is formed.

Monomers condense to give a polymer and

by-products such as H2O, CH3OH are

formed.

2

Number of monomeric units decreases

steadily throughout the reaction

Monomers disappear at the early stage of

reaction

2

Molecular weight of the polymer is an

integral multiple of monomer

Molecular weight of the polymer need not be

an integral multiple of monomer

2

High molecular weight polymer is formed at Molecular weight of the polymer rises 2



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once. steadily throughout the reaction.

Longer reaction time give higher yield but

have a little effect on molecular weight Longer reaction time are essential to obtained

high molecular weight

2

Homochain polymer is obtained. Hetero-chain polymer is obtained. 1

Thermoplastics are produced, e.g.,

Polyethylene, PVC, etc. Longer reaction time are essential to obtained

high molecular weight

1

3 Explain briefly the applications of nano materials.

12 CO4 (K2)

(A) Medicine

(i)Nano drugs

Nano materials are used as nano drugs for the cancer and TB therapy.

(ii)Laboratories on a chip

Nano technology is used in the production of laboratories on a chip.

(iii)Nano-medibots

Nano particles function as nano-medibots that release anti-cancer drug and treat

cancer.

(iv)Gold-coated nanoshells

It converts light into heat, enabling the destruction of tumours.

(B)Industries

(i)As Catalyst

It depends on the surface area of the material. As nano-particles have an

appreciable fraction of their atom at the surface, its catalytic activity is good.

(ii)In water purification

Nano-filtration makes use of nano-porous membranes having pores smaller than 10

nm. Dissolved solids and colour producing organic compounds can be filtered very easily from

water.

(iii)In Automobiles

Incorporation of small amount of nano-particles in car bumpers can make them

stronger than steel.

(iv)In food industry

The inclusion of nano-particles in food contact materials can be used to generate novel

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type of packing materials and containers.

(C)Electronics

(i) Quantum wires of nano-particles in food contact materials can be used to generate novel

type of packing materials and containers.

(ii) The integrated memory circuits have been found to be effective devices

(iii) Nano wires are used to build transistors without p-n junctions.

(iv) Nano radios are the other important devices, using carbon nanotubes.

(D)Bio-materials (Biology)

(i) Nano materials are used as bone cement and bone plates in hospitals.

(ii) It is also used as a material for joint replacements.

(iii) Nano technology is being used to develop miniature video camera attached to a blind

person’s glasses.

(iv) CNTs are used as light weight shielding materials for protecting electronic equipments

against electromagnetic radiation.

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3

4 Write not on( i) Supramolecular chemistry ii) Chemical Vapour Deposition 12 CO4 (K2)

( i) Supramolecular chemistry

Supramolecular chemistry is the domain of chemistry beyond that of molecules and focuses on

the chemical systems made up of a discrete number of assembled molecular subunits or

components. The forces responsible for the spatial organization may vary from weak

(intermolecular forces, electrostatic or hydrogen bonding) to strong (covalent bonding),

provided that the degree of electronic coupling between the molecular component remains

small with respect to relevant energy parameters of the component. While traditional chemistry

focuses on the covalent bond, supramolecular chemistry examines the weaker and reversible

noncovalent interactions between molecules.

These forces include hydrogen bonding, metal coordination, hydrophobic forces, van der

Waals forces, pi-pi interactions and electrostatic effects. Important concepts that have been

demonstrated by supramolecular chemistry include molecular self-

assembly, folding, molecular recognition, host-guest chemistry, mechanically-interlocked

molecular architectures, and chemistry. The study of non-covalent interactions is crucial to

understanding many biological processes from cell structure to vision that rely on these forces

for structure and function. Biological systems are often the inspiration for supramolecular

research. Supermolecules are to molecules and the intermolecular bond what molecules are to

atoms and the covalent bond.

6

ii) Chemical Vapour Deposition - This process involves conversation of gaseous molecules

https://en.wikipedia.org/wiki/Chemistry

https://en.wikipedia.org/wiki/Molecule

https://en.wikipedia.org/wiki/Integer

https://en.wikipedia.org/wiki/Intermolecular_force

https://en.wikipedia.org/wiki/Electrostatics


https://en.wikipedia.org/wiki/Covalent_bonding

https://en.wikipedia.org/wiki/Covalent_bond

https://en.wikipedia.org/wiki/Coordination_complex

https://en.wikipedia.org/wiki/Hydrophobic_effect

https://en.wikipedia.org/wiki/Van_der_Waals_force

https://en.wikipedia.org/wiki/Van_der_Waals_force

https://en.wikipedia.org/wiki/Pi-pi_interaction

https://en.wikipedia.org/wiki/Electrostatic

https://en.wikipedia.org/wiki/Molecular_self-assembly

https://en.wikipedia.org/wiki/Molecular_self-assembly

https://en.wikipedia.org/wiki/Folding_(chemistry)

https://en.wikipedia.org/wiki/Molecular_recognition

https://en.wikipedia.org/wiki/Host-guest_chemistry

https://en.wikipedia.org/wiki/Mechanically-interlocked_molecular_architectures

https://en.wikipedia.org/wiki/Mechanically-interlocked_molecular_architectures

https://en.wikipedia.org/wiki/Non-covalent_interactions

https://en.wikipedia.org/wiki/Systems_biology



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into solid nanomaterials in the form of tubes, wires or thin films. First the solid materials are

converted into gaseous molecules and then deposited as nanomaterials.

Example: CNT preparation.

The CVD reactor consists of a higher temperature vacuum furnace maintained at inert

atmosphere. The solid substrate containing catalyst like nickel, cobalt, iron supported on a

substrate material like silica, quartz is kept inside the furnace. The hydrocarbons such as

ethylene, acetylene and nitrogen cylinders are connected to the furnace. Carbon atoms,

produced by the decomposition at 10000C, condense on the cooler surface of the catalyst.

Fig. Chemical Vapour Deposition

As this process is continuous, CNT is produced continuously.

6

5 Write an informative note on the properties of nanomaterials. 12 CO4 (K2)

(a) Melting points

Nano-materials have a significantly lower melting point and appreciable reduced lattice

constants. This is due to huge fraction of surface atoms in the total amount of atoms.

(b)Optical properties

Reduction of materials has pronounced effects on the optical properties. Optical

properties of nano-materials are different from bulk forms.

The change in optical properties is caused by two factors

(i) The quantum confinement of electrons within the nano-particles increases the energy

level spacing.

(ii) Surface plasma resonance, which is due to smaller size of nano-particles than the

wavelength of incident radiation.

(c)Magnetic properties

Magnetic properties of nano materials are different from that of bulk materials. Ferro-

magnetic behavior of bulk materials disappear, when the particle size is reduced and transfer

to super-paramagnetics. This is due to the huge surface area.

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(d)Mechanical properties

The nano-materials have less defects compared to bulk materials, which increases the

mechanical strength.

(i) Mechanical properties of polymeric materials can be increased by the

addition of nano-fillers.

(ii) As nano-materials are stronger, harder and more wear resistant and

corrosion resistant, they are used in spark plugs.

(e)Electrical properties

(i) Electrical conductivity decreases with a reduced dimension due to increased

surface scattering. However, it can be increased, due to better ordering in micro-structure.

(ii) Nanocrystalline materials are used as very good separator plates in batteries,

because they can hold more energy than the bulk materials.

(f)Chemical properties

Any heat treatment increases the diffusion of impurities, structural defects and

dislocations and can be easily push them to the nearby surface. Increased perfection will

have increased chemical properties.

2

2

2

6 Explain in details about Injection moulding of plastics

12 CO4 (K2)

Injection Molding

Injection molding is the one of the most commonly used manufacturing process for the

plastic components. It is used to manufacture thin walled plastic parts for a wide

variety of shapes and sizes. In this process, the plastic material is melted in the

injection chamber and then injected into the mold, where it cools and finally the

finished plastic part is ejected.

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Working Principle

In this process, the plastic materials usually in the form of powder or pellets are fed

from hopper into the injection chamber. The “piston and cylinder” arrangement is used

to forward the material inserted from the hopper in to the injection chamber. The

plastic material is heated in the injection chamber with the application of heating

elements. The cooling system is also used to maintain the temperature of the injection

chamber. The molten plastic material is then injected into the mold cavity through a

nozzle. The molded part is cooled quickly in the mold. Thereafter, the final plastic part

is removed from the mold cavity. The process cycle for injection molding is very

short, typically between 2 to 60 seconds. The complete injection molding process is

divided into four stages: clamping, injection, cooling and ejection.

4

UNIT IV –Engineering materials

1 Describe the applications of abrasives.

12 CO3 (K2)

Applications of Abrasives:

1. As loose powder

To clean the surface prior to coating,abrasive powders are used.

e.g Quartz and Garnet

2 CO3

2. As abrasive paper or cloth

Abrasive paper is a hard paper coated or bonded with abrasive grains using

some glue

The roll of paper or cloth is made to pass through a series of rollers, and a thin

coating of glue is applied on its upper side.

It is then passed under a hopper from which the grit of abrasive is allowed to

fall and spread evenly on the glued paper or cloth.

The paper or cloth is again applied with a thin coating of glue and

dried in a warm drying room. The dried abrasive paper roll is then cut into

sheets of desired sizes. Finally abrasive papers are allowed to age for few

days, so that the glue sets firmly.

Depending upon the hardness, grain size,uniformity,chemical

composition and purity of abrasives, different number of abrasive papers or

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cloths are sold in the market.

4

Uses.

It is used to prepare smooth wood, metal and plastic surfaces.

2

2 Describe the following properties of refractories in detail

(i) Refractoriness

(ii) Dimensional stability

(iii) Thermal Spalling

12 CO3 (K2)

(i) Refractoriness

It is the ability to withstand very high temperature 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

interms 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

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To determine the purity of the refractories

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 is placed in electric furnace. The furnace is heated at a standard

rate of100C 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 temperature at which a std dimensioned specimen of a

refractory undergoes 10% deformation with a constant load of 3.5 or

1.75 Kg/cm. The load bearing capacity of a refractory can be measured

by RUL test. A good refractory should have high RUL value

(ii) Thermal spalling:

Property of breaking, cracking or peeling of refractory material

under high temperature. Thermal spalling may be due to rapid change

in temp or slag penetration. A good refractory should show good

resistance to thermal spalling.

3

(iii) Dimensional stability

Resistance of refractory to any volume change when exposed to

high temperature over a prolonged time. Refractories may undergo

reversible or irreversible dimensional changes. A good refractory

should show minimum level of reversible dimensional changes with

temperature.

3

3 Discuss in detail about the following?

(i) Water proof cement

(ii) White cement

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Water Proof Cement:

Water proof cement or hydrophobic cement is obtained by adding

water proofing agents like calcium stearate, aluminium stearate and gypsum

with tannic acid to ordinary Portland cement during grinding.

Properties

It is more expensive than ordinary Portland cement

It acts as pore blocking and water repelling agents.

3

Uses :

(i) It is used to make concrete which is impervious to water

under pressure.

(ii) It is used in the construction, where absorption of waterneed

to be avoided.

(iii) It is used in the construction of bridges and stuctures under

water.

3

White cement or White Portland cement:

It is obtained by calcinating the raw materials of Portland cement

which are free from iron oxides. It is white in colour due to the absence of

ferric oxide.

3

Uses: It is used for making tiles, mosaic works with some coloring agents like

yellow ochre, Venetian red etc. It is used for repairing and joining marble pillars and

blocks.

3

4 How will you manufacture Alumina bricks? 12 CO3 (K2)

ALUMINA BRICKS

Contain 50% or more of aluminium oxide

Manufacture:

1.Grinding and Mixing:

Calcined bauxite, silica and grog (calcined fire clay) are ground

well to fine powder and mixed with required amount of water to

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convert into pasty mass.

2.Moulding

The pasty mass is converted into bricks by the general moulding

technique like mechanical pressing or

slip casting.

3.Drying and Firing:

The bricks after moulding is dried slowly to remove the

moisture and then fired at about 1200 to 14000 C for 6-8 days

Properties:

Alumina bricks are acidic refractories

They possess very low coefficient of expansion

They also possess high porosity and high temperature load

bearing capacity

They are inert to the action of gases like CO2, H2 and natural

gas.

They are also very stable to both in oxidsing and reducing

conditions

They possess better resistance to thermal spalling than silica

bricks.

4

5 How will you manufacture silicon carbide brick? Write its properties

12 CO3 (K2)

Silicon Carbide (SiC):

Manufacture:

Silicon Carbide is manufactured by heating sand (60%)and coke

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(40%) with some saw dust sand 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 then shaped, dried and fired.

Properties

1 Silicon carbide possesses a high thermal conductivity, low

expansion and high resistance to abrasion and spalling.

2. They are mechanically strong. Mohr’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

4

6 How will you manufacture Magnesite bricks, and write its properties?

12 CO3 (K2)

Magnesite bricks

Magnesite bricks contain mainly MgO. They are generally manufactured by

mixing calcined magnesite with caustic magnesia or iron oxide or sulphite lye as

binding material

Manufacture

1. Grinding and mixing

The raw materials (calcined magnesite) and binding materials (caustic

magnesia or iron oxide or sulphite lye) are ground to fine powder and mixed

with water to a asty material.

2. Moulding

Moulding is usually done by machine pressing to a required shape

3. Drying and Firing

Drying is carried out at ordinary temperature to remove the moisture. Firing

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is done in a kiln at 1500

0c for 8 hours and then cooled slowly.

Properties

Magnesite bricks are basic refractories

They can be used upto 20000c without load and upto 15000c under a load 3.5

Kg/cm2

They have good resistance to basic slags, but combine with H2O and CO2.

They possess good strength, little shrinkage and have lot of spalling.

They have poor resistance to abrasions

4


1 Derive the expression for Beer – Lamberts law. State its limitation.

12 CO4 (K2)

“When a beam of monochromatic radiation is passed through a solution of an absorbing

substance the rate of decrease of intensity of the radiation dI with the thickness of the

absorbing solution dx is directly proportional to the intensity of the incident radiation I as well

as the concentration of the solution C

3

-dI/dx=kIC 3

log Io/I=k/2.303Cx 3

Beer- Lamberts law is obeyed only if the radiation used is monochromatic.

It is applicable only for dilute solutions.

The temperature of the system should not be allowed to vary to a larger extent.

It is not applied to suspensions.

Deviations may contain if the solution contains impurities.

Deviations may also occur if the solution undergoes association or dissociation.

3

2 Explain the mechanism of photo physical process with the help of Jablonski diagram. 12 CO4 (K2)

Spin multiplicity:-Most molecules posses an even number of paired electrons in ground

state.The spin multiplicity of the state is given as 2S + 1, where S is the total spins of the

electrons When the spins are paired

then S = s1+ s2 = +1/2 + (-1/2) = 0

Hence 2S + 1 = 2x0 + 1 =1, the spin multiplicity is 1.

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2

Non-radiative transitions:-Such a transition is from the higher excited states (S1, S3 or T2,

T3) to the first excited state (S1 or T1).

2

Internal Conversion: These transitions involve the return of the activated molecule from the

higher excited state to the first excited states. The energy of the activated molecule is dissipated

in the form of heat through molecular collisions.This process occurs in less than about 10-11s

S3-→ S1 T3-→ T1 S2-→ S1 T2-→ T1

2

Inter system crossing:The process in which the energy of the activated molecule is lost

through transition between state of different spin multiplicity. Even though these transitions are

forbidden, they occur at relatively slow rates

S2-→ T2 S1-→ T1

2

Radiative transition:These transitions involve the return of the activated molecule from the

singlet excited state S1 and the triplet excited state T1 to the singlet ground state S0. So, such a

transition is accompanied by emission of radiation

2

3 Explain the principle and five components of UV-visible spectrophotometer. 12 CO4 (K2)

Principle: UV – Visible spectra arises from the transition of valence electrons from the ground

state to excited state by absorbing light from UV (100 – 400 nm) or visible region (400 –

750nm). It is a type of absorption spectra.

2

Blockdiagram

2

Components:

Radiation source: Hydrogen or Deuterium lamps are radiation source for UV region and

tungsten filament lamp for visible region.

2

Monochromators: The monochromators is used to select a particular wavelength. 1

Cells: The cells are made up of quartz glass are used to hold the sample which should fulfill

the following conditions.

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They must be uniform in construction.

The material should be inert to solvents.

They must be transparent to UV and Visible light.

Detectors: The converts the radiation in to current which is directly proportional to the

concentration of the solution eg. Photo multiplier tube or Photocells.

1

Recorder: The recorder records the signal from the detector and shows a display. 1

Working 2

4 Explain the principle, components and working of IR spectroscopy 12 CO4 (K2)

Principle: IR Spectra is produced by the absorption of energy by a molecule in the infrared

region and the transitions occur between vibrational levels.

Range of IR radiation:

Near Infrared = 12500 – 4000 cm-1,Infrared = 4000 – 667 cm-1,Far Infrared = 667 – 50 cm-1

2

2

Components:Radiation source: The main source of radiation is Nichrome wire or Nernst

glower which is a filament containing oxides of Zr, Th, Ce held together with a binder.

2

Monochromators: It allows the light of the required wavelength to pass through light of other

Sample cell: The cells must be transparent to IR radiation are used to hold the sample.

2

Detector: Detectors are used to convert thermal radiant energy into electrical energy. 1

Recorder: The recorder record the signal coming out from the detector 1

Working:The radiation emitted by the source is split into two parallel beams. One of the

beams passes through the sample and the other passes through the reference sample. When the

two beams of light recombine they produce a signal which is measured by detector. The signal

from the detector is recorded by the recorder

2

5 Identify any one analytical method to estimate sodium present in aqueous media. 12 CO4 (K2)

Principle: Flame photometry is based on the measurement of intensity of the light emitted

when a metal is introduced into a flame.

Principle:

Evoporation Vapourisation Dissociation

M+X- MX MX

Thermal Excitation h Emission

X+ M M* M (ground state)

(excited state)

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Instrumentation

Burner - flame excitation unit Mirror -radiation is emitted: to increase amount of radiation concave mirror used Slits - entrance slits: permit radiation

Exit slit : prevent entry of interfering lines Monochromator (or) prism (or) grating (or)filter

- allows the light of required wavelength Detector – measures the intensity of radiation -

converts radiation in to electric current.

Amplifier - record the current.

2

Working

Air + Sample solution + Fuel gas mixture

Burnt in burner

Radiation emmited and passed

Lens,Filter, Detector, Amplifier,Recorder.

Expt carried out for series of std.solutions

Graph plotted between concentration and intensity of emitted light.

2

ESTMATION OF SODIUM BY FLAME PHOTOMETRY

Instrument is switched on

Air & gas supply regulated

Distilled water is sent.

Warmed for 10 mins

Instrument adjusted for zero degree

Sodium produced yello emission at 589 nm , the instruments is set

Readings are noted for series of NaCl

5

Graph plotted between concentration and intensity of emitted light.

1

6 Discuss the applications of UV-Spectroscopy. 12 CO4 (K2)

Predicting relationship between different group 2

Detection of impurities: UV Visible spectroscopy is the best method for detecting impurities

in organic compounds because

The bands due to impurities are very intense.

Saturated compounds have weak absorption band and unsaturated compounds have

strong absorption band.

2

The kinetics of chemical reaction: The progress of a chemical reaction can be easily followed

by examining the UV-spectra of test solution at different time intervals. The concentration of

either the reactant or product can be followed

2

Determination of calcium in blood serum. Calcium in blood serum in indirectly determined

by converting the Ca present in 1 ml of serum as calcium oxalate, and dissolving the calcium

oxalate in dilute sulphuric acid and treated with ceric sulphate solution.

2

Quantitative analysis: UV absorption spectroscopy is used for the quantitative determination 2



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of compounds based on Beer-Lambert‟s law.

Dissociation constant of acid and bases pKa=pH+log(HA)/(A-)

Study of tautomeric equilibrium, Determination of molecular weight 2

Note : 6 Questions with answer key must be prepared in each unit and maximum two sub divisions are allowed.

PART – C (20 Mark Questions with Key)

S.No Questions Ma

rk

C

Os

BTL

UNIT I – WATER TECHNOLOGY

1 Explain the demineralization of water by ion exchange process. How are exhausted

cation and anion exchange resins regenerated?

20 C

O

1

(K2)

6

This process removes almost all the ions (both anions and cations) present in hard water.

Demineralization process is carried out by using ion exchange resins.

1. Cation exchanger

Resins containing acidic functional groups (-COOH,-SO3H) are capable of exchanging their

H+ ions with other cations of hard water. It is represented as RH2.

2. Anion exchanger

Resins containing basic functional groups (-NH2,-OH) are capable of exchanging their anions

with other anions of hard water. It is represented as R (OH) 2.

Process

The hard water first passed through a cation exchange column, which absorbs all the cations

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like Ca

2+, Mg

2+, Na

+, K

+, etc., present in the hard water.

RH2+CaCl2 → RCa+2HCl

RH+NaCl → RNa+HCl

The cation free water is then passed through a anion exchange column, which absorbs

all the anions like Cl-, SO4

2-,HCO3

-,etc., present in the water.

R’ (OH)2+2HCl →R’Cl2+2H2O

The water coming out of the anion exchanger is completely free from cations and

anions. This water is known as demineralised water or deionised water.

Regeneration

When the cation exchange resin is exhausted, it can be regenerated by passing a solution of dil

HCl or dil H2SO4.

Similarly, when the anion exchange resin is exhausted, it can be regenerated by passing a

solution of dil NaOH.

3

2 Explain internal treatment of boiler feed water 20 C

O

1

(K2)

Carbonate conditioning

Scale formation can be avoided by adding Na2CO3 to the boiler water. It is

used only in low pressure boilers. The scale forming salt like CaSO4 is converted into

CaCO3, which can be removed easily.

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Phosphate conditioning

Scale formation can be avoided by adding sodium phosphate. It is used in high pressure boilers.

The phosphate reacts with Ca2+

and Mg2+

salts to give soft sludges of calcium and magnesium

phosphates.

Generally 3 types of phosphates are employed

Colloidal conditioning

Scale formation can be avoided by adding colloidal conditioning agents

like kerosene, agar-agar, gelatin, etc., It is used in low pressure boilers.

These colloidal substances get coated over the scale forming particles

and convert them into non-adherent, loose precipitate called sludge,

which can be removed by blow down operation.

Calgon conditioning

Calgon is sodium hexa meta phosphate Na2 [Na4(PO3)6]. This substance

interacts with calcium ions forming a highly soluble complex and thus

prevents the precipitation of scale forming salt.

The complex Na2 [Ca2 (PO3)6] is soluble in water and there is no problem

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of sludge disposal. So calgon conditioning is better than phosphate conditioning.

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UNIT II - CORROSION AND PROTECTIVE COATING

1 Name the chief constituents of paints and explain their functions. 20 C

O

2

(K2)

Paint is a mechanical dispersion of one or more finely divided pigments in a

medium (thinner vehicle). When a paint is applied to a metal surface, the thinner

evaporates, while the vehicle undergoes slow oxidation forming a pigmented film.

Constituents and their functions of a paint

1. Pigments :

Pigments are colour producing substances in the paint

Functions

(i)It gives colour and opacity to the film.

(ii) It also provides strength to the film.

(iii) It protects the film by reflecting the destructive uv rays.

(iv) It increases weather resistance of the film.

2. Vehicle (or) drying oil:

This is non volatile portion of a medium and film forming constituents of

paint.These are high molecular weight fatty acids present in vegitable and animal oils.

Functions

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Thinners (or) solvents

Functions

4. Extenders (or) fillers

Functions

Driers

Functions

Plasticisers

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Anti-skinning agents

2

2

2 Explain sacrificial anode and impressed current cathodic techniques for the

prevention of corrosion.

20 C

O

2

(K2)

The principle involved in the electrochemical protection (or) cathodic protection is

to force the metal to behave like a cathode. The important cathodic protections are

(i) Sacrificial anodic protection

(ii) Impressed current cathodic protection

1. Sacrificial anodic protection method

In this method, the metallic structure to be protected is made cathode by

connecting it with more active metal .

So that all the corrosion will concentrate only on the active metal. The

artificially made anode thus gradually gets corroded protecting the original metallic

structure. Hence this process is otherwise known as sacrificial anodic protection.

Aluminium, Zinc, Magnesium are used as sacrificial anodes.

Applications of sacrificial anodic protection

(a) This method is used for the protection of ships and boats. Sheets of Mg or Zn

are hung around the hull of the ship (Fig. 3.17). Zn or Mg will act as anode compared to

iron (ship or boat is made of iron), so corrosion concentrates on Zn or Mg. Since they

are sacrificed in the process of saving iron, they are called sacrificial anodes.

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(b) Protection of underground pipelines, cables from soil corrosion

(c) Insertion of Mg sheets into the domestic water boilers to prevent the formation

of rust

(d) Calcium metal is employed to minimize engine corrosion.

2. Impressed current cathodic protection method

In this method, an impressed current is applied in the opposite direction of

the corrosion current to nullify it, and the corroding metal is converted from anode to

catho This can be done by connecting negative terminal of the battery to the metallic

structure, to be protected, and positive terminal of the battery is connected to an inert

anode. Inert anodes used for this purpose are graphite, platinised titanium. The

anode is buried in a “back fill” (containing mixture of gypsum, coke, breeze,

sodium sulphate). The “back fill” provides good electrical contact to anode

Applications of impressed current protection Structures like tanks, pipelines, transmission line towers, underground water

pipe lines, oil pipe lines, ships, etc., can be protected by this method.

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UNIT III – POLYMER AND NANO TECHNOLOGY

1 Explain the mechanism of free radical polymerization 20 C

O

3

(K2)

i) Initiation

Initiation involves two reactions.

a) First Reaction

First Reaction involves production of free radicals by homolytic dissociation of an initiator (or

catalyst) to yield a pair of free radicals (R

.)

b) Second Reaction

Second Reaction involves addition of this free radical to the first monomer to produce chain

initiating species.

ii) Propagation

It involves the growth of chain initiating species by the successive addition of large number of

monomers.

iii) Termination

Termination of the growing chain of the polymer occurs either by coupling reaction or

disproportionation.

a) Coupling (or) Combination

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It involves coupling of free radical of one chain end to another free radical to form

macromolecule (dead polymer).

b) Disproportionation

It involves transfer of a hydrogen atom of one radical centre to another radical centre forming two

macromolecules, one saturated and another unsaturated.

The products of addition polymerisation is known as dead polymers. 2 Explain in Detail the fabrication process of plastics through compression moulding

20 C

O

3

(K2)

Compression Moulding is a method of moulding in which the moulding material, generally preheated, is

first placed in an open, heated mould cavity. The mold is closed with a top force or plug member,

pressure is applied to force the material into contact with all mold areas, while heat and pressure are

maintained until the molding material has cured. The process employs thermosetting resins in a partially

cured stage, either in the form of granules, putty-like masses, or preforms.

7

https://en.wikipedia.org/wiki/Molding_(process)

https://en.wikipedia.org/wiki/Mould

https://en.wikipedia.org/wiki/Heat

https://en.wikipedia.org/wiki/Pressure

https://en.wikipedia.org/wiki/Resin

https://en.wikipedia.org/wiki/Putty



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Compression molding is a high-volume, high-pressure method suitable for molding complex, high-

strength fiberglass reinforcements. Advanced composite thermoplastics can also be compression molded

with unidirectional tapes, woven fabrics, randomly oriented fiber mat or chopped strand. The advantage

of compression molding is its ability to mold large, fairly intricate parts. Also, it is one of the lowest cost

molding methods compared with other methods such as transfer molding and injection molding;

moreover it wastes relatively little material, giving it an advantage when working with expensive

compounds

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UNIT IV –Engineering materials

https://en.wikipedia.org/wiki/Fiberglass

https://en.wikipedia.org/wiki/Thermoplastic

https://en.wikipedia.org/wiki/Transfer_molding

https://en.wikipedia.org/wiki/Injection_molding



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1 With a neat diagram explain the manufacture of Portland cement?

20 C

O

2

(K2)

Raw materials :

(i) Calcareous materials, CaO Ex: Limestone, chalk.

(ii) Argillaceous materials, Al2O3 and SiO2 Ex: clay

(iii) Powdered coal (or) fuel oil.

(iv) Gypsum (CaSo4.2H2O)

3 C

O

3

Manufacture of Portland cement involves the following steps:

(i) Mixing of raw materials

(ii) Burning

(iii) Grinding

(iv) Storage and Packing

3

(i) Mixing of raw materials:

(a) Dry Process (b) Wet Process

(a) Dry Process:

In dry process, the raw materials like limestone and clay (3:1) are dried and

mixed in definite proportions to get dry raw mix. Then it is stored in a concrete

storage tank called “Silos”

(b) Wet process :

In wet process, the raw materials in definite proportions are finely

crushed,powdered and stored in a storage tank. The argillaceous material(clay) is

thoroughly washed with water to remove any adhering organic matter and stored in

a basin. Then the powdered limestone and wet clay are led into grinding mills

where they are mixed to form a paste called “slurry”. The slurry is led to a

correcting basin where its chemical composition may be adjusted. Thus the slurry

containing about 38 to 40% water is stored in storage tank. with water and the

slurry (paste like) is fed at the top of the rotary kiln.

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(ii) Burning:

The burning process is usually done in rotary kiln which is a long horizontal

steel cylinder coated with refractory bricks and capable of rotating at 1 rpm 9

Revolution per minute). The rotary kiln is set at a slight inclination of about 5-60 in

order to allow the raw materials fed at one end to travel slowly to the firing and

discharge exit end.

The slurry of raw materials is allowed to enter from the top end of the rotary kiln.

Simultaneously the burning fuel and air are introduced from the lower end of kiln. The

slurry gradually comes down in the kiln into the different zones

4

(a) Drying Zone:

The upper part of the rotary kiln is known as drying zone where the temperature is about 4000C

. Due to the presence of hot gases in this zone, water is evaporated from the slurry.

(b) Calcinations zone:

The middle part of the rotary kiln is known as calcining zone where the

temperature ranges from 700 -10000

C. In this zone lime stone is

decomposed into CaO and CO2

CaCO3 CaO +CO2

Lime Stone Quick lime

(c) Clinkering Zone :

The lowest part of the zone is called as clinkering zone, where the

temperature is maintained about 1250-15000C. In this zone lime reacts with

clay (Containing Al2O3, Fe2O3 and SiO2) and forms aluminates and

silicates

2CaO+ SiO2 2CaO.SiO2

Di calcium Silicate

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3CaO+ SiO2 3CaO.SiO2

Tri calcium Silicate

The mixture is then finely powdered and fed into the top of the rotary kiln.

3CaO+ Al2O3 3CaO.Al2O3

Tri calcium Aluminate

4CaO + Al2O3 + Fe2O3 4CaO.Al2O3.Fe2O3

Tetra calcium alumino Ferrate

(ii) Cooling:

The hot clinker is cooled with atmospheric air and the hot air thus

produced is used for drying the coal before grinding.

3

(iii) Grinding:

The cooled clinker is then finely pulverized with 2-3% gypsum acts as

a retarding agent for quick setting of cement.

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(iv) Storage and Packing:

The cement coming out from the grinding mills is stored in a concrete

storage silos. Then the cement is packed in jute bags by automatic machines.

Each bag contains 50kgs of cement.

2 Explain in detail about setting and Hardening of cement.

20 C

O

2

(K2)

When the cement is mixed with water, hydration and hydrolysis of cement begin,

resulting in the formation of gel and crystalline products.

Setting: It is defined as the stiffening of the original plastic mass, due to initial gel

formation.

Hardening: It is defined as the development of strength, due to crystallization.

6 C

O

3

Chemical reactions involved in setting and hardening of cement:

When water is mixed with cement, hydration of tricalcium aluminate occurs rapidly and

the paste becomes quite hard within a short time. This process is known as initial setting

of cement.

3CaO.Al2O3 +6H2O 3CaO.Al2O3.6H2O

Role of gypsum in cement:

(i) In initial setting process gypsum is added during grinding of cement clinkers to

retard the rapid hydrationof C3A. Gypsum reacts with C3A to form insoluble calcium

sulphoaluminate complex.

C3A + 3CaSO4.2H2O C3A.3CaSO4.2H2O

(ii) After the hydration of C3A,C3S begins to hydrate to give tobermonite gel and crystalline

Ca(OH)2. The hydration of C3S takes place within 7days.

2(3CaO.SiO2) + 6H2O 3CaO.2SiO2.3H2O + 3Ca(OH)2 + 500kJ/kg

(iii) Dicalcium silicate reacts with water slowly and gets finished 7-28days.

(2CaO.SiO2) + 4 H2O 3CaO.2SiO2.3H2O +Ca(OH) 2 + 250kJ/kg

(iv) Hydration of tetra calcium aluminoferrite takes place initially, the hardening takes place

finally through crystallization along with C2 S.

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4CaO.Al2O3.Fe2O3 + 7H2O 3CaO.Al2O3.6H2O + CaO.Fe2O3.H2O + 420K

Crystalline gel tobermonite gel

Thus the final setting and hardening of cement is due to the formation of tobermonite

gel plus crystallization of Ca(OH)2 and hydrated tricalcium aluminate.

6

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1 (i)Explain the molecular vibration in IR spectrum. Calculate the fundamental modes of vibration for non-

linear and linear molecule.

(ii) write the application of IR Spectroscopy

12

08

Stretching vibrations: During stretching, the distance between two atoms decreases or

increases, but bond angle remains unaltered.

Bending vibrations: During bending, bond angle increases or decreases but bond distance remains

unaltered.

3

Types of Stretching and bending vibrations

(i) Symmetric stretching: The atoms of the molecule are moving in the same direction.

(ii) Asymmetric stretching: The atoms of the molecule are moving in opposite direction.

3

Water (H2O) (N=3) It is a non-linear molecule. Hence, 3N-6 = 3x9-6 = 3 Fundamental

vibrational modes.

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(i) Symmetric stretching (ii) Asymmetric stretching (ii) Bending vibration

υ1 = 3652 cm-1 υ2 = 3756 cm-1 υ1 = 1596 cm-1

4. Carbon dioxide (CO2) (N=3)

It is a linear molecule. Hence, 3N-5 = 3x3-5 = 4 Fundamental vibrational modes.

(i) (ii) (iii) (iv)

Symmetric stretching Asymmetric stretching In-plane Bending Out-plane bending

υ1 = 1340 cm-1 υ2 = 2350 cm-1 υ3 = 666 cm-1 υ4 = 666 cm-1

(ii) Identification of organic compounds. : IR spectroscopy is very useful in identification of organic

compounds.

Identification of functional groups: The region from 4000 – 1400 cm-1 in IR spectrum is useful for

functional group analysis

2

Testing the purity of a sample: Presence of an impurity can be detected by their characteristic peaks.

1

Determination of symmetry of a molecule: The symmetry of a molecule whether linear or nonlinear can

be determined from the IR spectrum.

Example: IR spectra of H2O gives 3 peaks at 667 cm-1, 1330cm-1, 2349 cm-1. Since non-linear

molecule should exhibit (3N-6) = 3 peaks, the compound is non linear.

1

Study of hydrogen bonding molecule: Intermolecular and Intramolecular hydrogen bonding can be

differentiated by taking a series of spectra of a compound at different concentrations. Intermolecular

hydrogen bonding decreases with dilution and the intensity of such peaks will also decrease.

Intramolecular hydrogen bonding on the other hand will show no such change.This can be explained by

taking the ortho and para nitrophenols.

2

Study of progress of a chemical reaction

The rate the reaction can be determined by taking IR spectra at regular intervals of time

Example: Oxidation of secondary alcohol to ketone

Secondary alcohol gives the absorption band at 3570cm-1 due to - OH stretching slowlydisappears and a

new band appears at 1725cm-1 due to C=O stretching.

2

2 (i) Explain the principle and instrumentation of colorimetric?

(ii) With the help of colorimeter principle estimate the iron content in the solution.

12

8

Colorimetry:

Absorption of radiant energy in the visible region.(400 – 750 nm)

Instrument used - COLORIMETER

2

Principle :

Convenient for coloured substances.

Intensity of colour measured by photo electric colorimeter.

Concentration of coloured solution be measured by Beer-Lambert‟s law.

Colourless solution + complexing agent = coloured complex (absorb light)

Example. Cuprous ions + NH4OH (Blue coloured complex)

4

Instrumentation :

Radiation source (beam of light) eg. Tungsten filament Lamp 400 – 750 nm

Filter or monochromator (select light of required wavelength.

Slits a) entrance slit - provide narrow band b) exit slit - select narrow band

Cell ( test sample solution )

Detector - detect radiation.

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Current is directly proportional to the intensity of incident radiation.

Meter Absorbance of light be measured.

Working of Colorimeter: Beam of light passed through radiation source.

1. Filter and slits, select the required wave length.

2. Detector generates current

3. Light transmitted will be more, if the coloured solution is most dilute.

Current Light transmitted 1/ Concentration

2

Estimation of Iron By Colorimetry:

Principle: 3-

Fe3+

+ 6 KCNS [Fe(CNS)6] + 6K+

Blood red coloured Complex

2

Standard iron solution Potassium thio 1:1 con

Cyanate solution HCl

0.865 gms FAS 20 gms KCNS 50 ml con .HCl

+

Dissolved in water 50 ml distilled water

Conc.HCl dissolved in 100 ml

Diluted to 1 litre water

1ml = 0.1 mg Fe

2

Procedure: Series of std solution be prepared Fe

3++ KCNS + 1:1 CONC.HCl

Colorimeter is set at zero absorbance.

Absorbance at each std soln be measured. Absorbance A =ЄC x

2

Graph plotted between absorbance vs concentration.

1

Applications of Colorimetry: Determination of Molar composition

Instability constants of complexes

Dissociation constants (Pk)of an acid-base indicator

Structure of inorganic compounds, complexes

Molecular weight of a compound

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Note : 2 Questions with answer key must be prepared in each unit and maximum two sub divisions are allowed.

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