sample copy. not for distribution. concept of symbol, valency, formula, atomic mass, molecular mass,...

Sample Copy. Not For Distribution.

i

A Hand Book on

Engineering Chemistry


ii

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iii

A HAND BOOK

ON

ENGINEERING

CHEMISTRY

A TEXT BOOK FOR DIPLOMA STUDENTS

SPECIALLY WRITTEN FOR DIPLOMA STUDENTS FOR THE NORTH- EASTERN

STATES OF INDIA AS PER THE REVISED CURRICULUM DEVELOPED BY

NATIONAL INSTITUTE OF TECHNICAL TEACHERS’ TRAINING &

RESEARCH (NITTTRs)

BY

DR. RAJENDRA PRASAD,

MIZORAM POLYTECHNIC, LUNGLEI

EDUCREATION PUBLISHING (Since 2011)

www.educreation.in


iv

PREFACE & ACKNOELEDGEMENT

Technological advancements in the present time involves innovation at

all stages of research, development, diffusion and use; and in this process

of continuous advancement demands all round skilling of the students as

well as improvements in the employability of the pass out students. The

curriculum plays an important role in the process of skilling of the

students. Keeping all these under considerations, the curriculum of most

of the states in the North-eastern states of India either has been revised or

are in the progress.

The availability of a suitable book becomes a big problem for the

students and teachers as per the new/ revised curriculum/ syllabus; and to

help in the teaching- learning process this book has been written.

This book contains only twelve units; and each unit has been further

divided into sub units.

It is hoped that the text matters given in this book will attract students

and teachers, and will enable the students to develop a greater interest in

the science & technology, especially in the field of engineering

chemistry.

Any suggestion aimed to improve the content of the book will be

highly appreciated.

I owe my gratefulness to all those who have supported me in writing

this book.

I extend my thanks to the entire team of publisher for their dedication

and efficient support in publishing this hand book.

Dr Rajendra Prasad,

Mizoram Polytechnic, Lunglei

****


v

ABOUT THE AUTHOR

Dr Rajendra Prasad is teaching Chemistry in

Mizoram Polytechnic, Lunglei since 1985. He

completed his Master‘s in Chemistry from Patna

University, Patna in 1984 and his Doctorate work

from CCC University, Meerut in 1998. In 2009, he

completed his M. Tech in engineering Education

from Panjab University, Punjab. He is a dynamic and

vibrant personality and has rich working experience

in technical education in different capacities, both administrative and

teaching. At present, he is Institutional Project coordinator of AICTE-

NEQIP, and under this grant in aid he organized a seminar on the topic

“Solid Waste Management and safe drinking water in context of

Mizoram and other states in India”. The proceeding of the seminar has

been published with ISBN: 98-1-61813-473-8 from Educreation

Publishing, New Delhi.

****


vi

CONTENT

SECTTION A

1.0 GENERAL CHEMISTRY 1

1.1 Concept of symbol, valency, formula, atomic

mass, molecular mass, elementary idea of

atomic structure (Review).

2

1.2 Solution 13

12.1 Classify and explain solution according

to concentration

12.2 Distinguish among suspension, colloids and

true solution.

12.3 Define and explain solubility, effect of

tempeature on solubility

12.4 Mention practical applications of colloids in

different situations

1.2.4.1 Colloidal impurities in drinking

ansewage water.

1.2.4.2 Finely divided colloidal particles in

aircauses Air-Pollution.

Assignment and Class test

13

15

17

18

18

18

1.3 Acid, Base and Salt 21

1.3.1 Define and classify acid, base and salt

(Review)

21

1.3.2 Define and explain normal solution, molar

solution, titration and indicator

24

1.3.3.Define pH of a solution and pH Scale 25

1.3.4. Calculate pH from H

+ ion concentration

26

1.3.5.Mention application of pH in industry such as 27

1.3.5.1 pH of a boiler feed water 27

1.3.5.2 Role of pH in sewage treatment 28

1.3.5.3 pH in Sugar, Paper industry 29

1.3.5.4 Buffer Solution, types and

application.

30


1.4 Chemical Bonding 31

1.4.1 Covalent Bond, Ionic Bond, Hydrogen 31


vii

Bond andMetallic Bond


2.0 CHEMISTRY OF WATER 36

2.1 State the different types of impurities present in

natural water and name impurities undereach

of them types.

36

2.2 Explain how natural water gets contaminated

with the impurities.

37

2.3 Explain the action of soap on water 37

2.4 Define and explain soft and hard water with

illustrations

38

2.5 Classify and explain hardness of water with

illustration 38

2.6 State different ways of expressing concentration

of impurities in water includinghardness.

39

2.7

Name the bad effects caused by natural waterwhe

n used in domestic as well as industrial purpose.

40

2.8 State and Explain the remedial measures of the

following bad effects of natural water inboiler.

Scales and sludges

Caustic Embrittlement

Priming and foaming

Corrosion

41

2.9 Define boiler feed water 44

2.10 Describe with help of diagram of the following

water treatment Process.

45

2.10.1 Lime soda process 45

2.10.2 Permuit or Zeoilite process 48

2.11 Describe with the help of block diagram the

treatments done on asample of raw water to

produce drinking water and boiler feed water.

Solve problems on

a) bad effects on natural water

b)water treatment process.


50

3.0 PHYSICAL CHEMISTRY 53

3.1Catalyst, types, characteristics and

application of Catalyst in Industries

53

3.2Radioactivity Introduction, Characteristics of 56


viii

alphas,beta and gamma rays, half-life

period, artificial fission, atomic fusion,

application in different fields

4.0 METALLURGY AND ALLOYS 66

4.1 Types of metals & properties 66

4.2 General Metallurgical process 66

4.3 Metallurgy of iron by blast furnace

(principle only)

69

4.4 Classification of Steel based on its carbon

content and its application

74

4.5 Properties of cast iron, wrought iron and steel 75

4.6 Effects of adding alloying elements on the

properties of steel

77

4.7 Definition of alloy and purpose of alloying

Method of preparation of alloy

(brief outline only)

78

4.8 Composition, properties and engineering uses

of following alloys :

Duralumin, Magnalium, Brass, Bronze,Monel

metal, Babbits metal, Gun metal and Alnico.

78

Solve problems, Assignments and class tests

5.0 REFRACTORIES 80

5.1Define refractories 80

5.2Classification 81

5.3Properties 82

5.3.1 Refractoriness 82

5.3.2 Strength 83

5.3.3 Thermal expansion 83

5.3.4 Porosity 84

5.4 Portland Cement

5.4.1 Composition

84

84

5.4.2 Properties 85

5.4.3 Types 87


ix

SECTION B

89

1.0 ELECTROCHEMISTRY 90

1.1 Define conductor, insulator, semi-conductor,

electrolyte and non-electrolyte with

examples.

90

1.2 State postulates of Arrhenuous and

electrolytic theory of dissociation

91

1.3 Demonstrate the phenomenon of electrolysis. 92

1.4 State and explain Faraday‘s 1st

and 2nd

laws of electrolysis

93

1.5 Define and explain conductance, specific

conductance, molar

conductance, electrochemical cell

97

Solve problems on electrolysis

Solve problems, Assignment and Class test.

2.0 FUEL 100

2.1 Explain importance of fuels in industries. 100

2.2 Define ‗fuel‘ and ‗combustion of fuel‘ with

examples.

100

2.3 State the classification of fuels into two

different ways,namely

101

2.3.1 Classification based upon occurrence with

examples.

101

2.3.2 Classification based upon state of

aggregation with examples. 101

2.4 Define calorific value and mention its units.

2.5 Distinguish between gross (or higher) and

net (or lower)calorific value.

102

102

2.6 State the relative merits and demerits

of solid, liquid and gaseous fuel

105

2.7 State the availability of different

fuels in India.

107

2.8 Define coal. 108

2.9 State and explain origin of coal. 108

2.10 Classify coal by rank. 108


x

2.11 Define pulverized coal 108

2.12.The advantage and disadvantage of

pulverized coal.

109

2.13 Explain proximate and ultimate analysis

of coal.

109

2.14 Define ‗Petroleum‘ or ‗Crude oil‘ 110

2.15 Describe the fractional distillation of

crude petroleum

110

2.16 Name the main products obtained from

crude petroleum and mention their

respective boiling ranges and uses.

112

2.17 State and explain important properties of

liquid fuelsnamely, viscosity, flash and

fire point, smoke point, aniline point,

knocking,octane number, cetane number,

anti-knocking properties.

112

2.18 State composition, preparation

and industrial applicationof coal gas,

water gas, producer gas, LPG, natural

gas and gobar gas.

114


3.0 LUBRICANTS 117

3.1 Define ‗lubricant‘ and ‗lubrication‘. 117

3.2 Mention the major functions of a lubricant. 118

3.3 Different types of lubricants with examples 118

3.4 Applications. 119


4.0 CORROSION 121

4.1 Define corrosion. 121

4.2 Descibe the causes of corrosion. 121

4.3 State the different types ofcorrosion of

metal.

122

4.4.Explain chemical corrosion of metals

and mention the names of the

corrosion products.

124

4.5 Explain rusting of iron 124


xi

4.6 Name the various methods of corrosion

control.

126


5.0 PROTECTIVE COATING 130

5.1 State the necessity of protective coating. 130

5.2 State the main types of protective coatings. 131

5.3 Recall the different kinds of organic and

inorganic (or metallic)protective coating.

132

5.4 Explain the term ― Paint ‖ 134

5.5 State the functions of component drying oil,

pigment, driers and thinners with examples.

135

5.6 Varnish, types and application. 136


6.0 ORGANIC CHEMISTRY 137

6.1 Organic chemistry and its scope in various

industries.

137

6.2 Tetravelancy of Carbon atom 137

6.3 Functional groups 138

6.4 Distinguish between organic and inorganic

compounds.

141

6.5 Homologous series alkane, alkene, alkyne,

alcohol, aldehyde, ketone,ether,carboxylic

acid.(general formula)

144

6.6 Preparation method of Methane, Ethane

Ethene and Ethylene

144

6.7 Benzene and its preparation and discuss

its derivatives.

150

7.0 POLYMER AND PLASTICS 151

7.1 Define polymer. 151

7.2 The types of polymerization. 152

7.3 Classify polymers 153

7.4 Properties of thermoplastics and thermosetting

polymers.

154

7.5 Define plastics 155

7.6 Name important plastic materials with

their properties and uses(in tabular form).

156


xii

Namely : Polythene, Polypropylene, polystyrene,

PVC, Nylon, Terelene,

Neoprene, Bakelite, Urea-formaldehyde and PET.

156

7.7 Mention examples of plastics used in

different situations :

158

i) Electrical insulation

ii) Lubrication

iii) Ropes and beams

iv) Optical lens

v) Adhesives

vi) Pipes and housing

vii) Fibre glass

viii) Carrybag



A Hand Book on Engineering Chemistry

1

Section A

CHEMISTRY-I


Rajendra Prasad

2

____________________________________

1. 1Concept of Symbol, Valency, Formula,

Atomic mass, Structure (Review)

Chemical Symbols

Chemical symbols are abbreviated forms of the names of chemical

elements, e. g: Ca for calcium; Si for Silicon, K for potassium etc.

Symbols are usually based on the Latin names, so they don't

always resemble the English names especially for elements

known in antiquity (eg: Au-gold, aurum).

Valency: It is the number of electrons present in the outer most

orbit of an atom.

Some useful elemental symbols in the context of cement follow, with

their approximate atomic weights:

Element Symbol Atomic weight Valency

Hydrogen H 1 1

Carbon C 12 4

Oxygen O 16 2

Nitrogen N 18 3

Sodium Na 23 1

Magnesium Mg 26 2

Aluminium Al 27 3

Phosphorus P 31 3,5

Sulfur S 32 2

Chlorine Cl 35.5 1

Potassium K 39 1

Calcium Ca 40 2

1.0 GENERAL CHEMISTRY



3

Chemical Formula

A chemical formula is just a convenient short name of a chemical and

they indicate its composition.

For example, common table salt is sodium chloride, NaCl. One

molecule of sodium chloride contains one atom of sodium and one atom

of chlorine.

Calcium carbonate, CaCO3, contains one atom of calcium, one of

atom carbon and three atoms of oxygen.

How to Write a Chemical Formula

Write the Symbol of the element and their corresponding valencies; then

exchange their valenvies. This will give you the respective formula.

Element Symbol Valency Formula

Hydrogen H 1 H 1

O 2

Formula: H2O Oxygen O 2

Atomic weights (also known as relative atomic masses)

In the old days, atomic weights were based on hydrogen with an atomic

weight of 1. This meant that calcium, with an atomic weight of 40, is 40

times as massive for the same number of atoms as hydrogen. In short,

mass of an atom of an element is called its atomic weight.

In other words, if you have 1 gram of hydrogen and 40 grams of

calcium, there would be the same number of atoms in each.

Relative Atomic Mass

Presently, atomic weights are not based on hydrogen, but on one-twelfth

of carbon-12. The relative atomic mass is the mass of an atom of a

substance relative to 1/12th

(one twelfth) of the mass a carbon -12

atom. There have been other definitions as well, but they are all the

same to within about 1%. Although called atomic weights, they are not

really weights because they are ratios and therefore dimensionless but the

term atomic weight is kept for historical reasons.

Atomic Mass Unit

One twelfth of one C-12 atoms are called atomic mass unit (u).

1u=1.6603x10 -24

g

1g= 6.022x10 23

u


Rajendra Prasad

4

The basic point is that the atomic weight tells us the relative masses of

atoms. A sodium atom is 23 times as massive as a hydrogen atom and a

sulphur atom is twice as massive as an oxygen atom. This is useful

because with this knowledge we can calculate how much, by weight, of

each element is present in compounds.

In sodium chloride again the atomic ratio of sodium to chlorine is

1:1. There is one atom of sodium and one of chlorine. The proportions by

weight are different. The weight (relative atomic mass) of sodium is 23

and of chlorine is 35.5. If we add these together we get the formula

weight of a sodium chloride molecule: 23+35.5=58.5.

So, the proportion of sodium in sodium chloride is:

23/58.5 x 100% = 39.3% by mass.

The proportion of chlorine in sodium chloride is:

35.5/58.5 x 100% = 60.7% by mass.

In calcium carbonate is CaCO3 the relative atomic mass of calcium is

40, of carbon is 12 and of oxygen is 16, and we have one atom of

calcium, one of carbon and three of oxygen. So, the formula weight of

calcium carbonate is 40+12+48=100. So, calcium carbonate contains

40% calcium, 12% carbon and 48% oxygen by mass.

Molecular Weight: It is the weight of a molecule or the mass of a

molecule is called its molecular weight. In the above two examples of

NaCl and CaCO3, it is clear the molecular weights ofNaCl and CaCO3 are

58.5 gram and 100 gram respectively.

The term 'formula weight' has been replaced by 'molar mass'.

Understanding the formula weight is easy, it is just the sum of the atomic

weights of all the atoms in the formula for a compound.

Molar mass: The mass of one mole of atoms is called its molar mass

and molar mass of atoms is equal to the mass of 6.022x10 23

atoms.

The value of molar mass is expressed as grams/mole.

Molar mass of some of the elements are given here for example:

Atom Molar mass (g/mol)

H 1

C 12

Mg 24

Ca 20

The molar mass is numerically the same, multiplied by 1 gram/mol. The

reason for this is to make the expression dimensionally correct. Atomic



5

weights aren't weights, they are ratios; for calcium carbonate, the molar

mass is 100 grams per mol.

'Mol' is the symbol for 'mole' and is linked to the number of atoms in

12 grams of carbon-12, the same as atomic weights. The mole can be

applied to elements or compounds.

Molar mass of molecule: The mass of one mole of a molecule is called

its molar mass i.e. molar mass of a molecule is equal to the mass of

6.022x10 23

molecules; and expressed as gram/mol. Molar mass of some

molecules are given in the following table:

Substance Formula Molar mass (g/mol)

Water H2O 18

Ethyne C2H2 26

Hydrochloric

acid

HCl 36.5

Sulphuric acid H2SO4 98

Solved Examples

i. Calculate the number of mole present in 20 g of water.

Solution:

No. of moles = Given mass of substance/ molar mass of substance

= 20g/ 18 g/mol = 1.11 moles [Molar mass of water = 18]

ii. Calculate the mass of 4 moles of Aluminium atom.

Solution:

Mass= Mole x Molar mass of Aluminium

= 4 moles x 27 g/ mol = 108 g

iii. Calculate the mass of 3.011 x 10 24

molecules of O2 when molar

mass of O2 is 32 g/mol.

Solution:

[Number of mole = Given mass of substance/ molar mass of

substance

Number of particles = (Given mass of substance/ molar mass of

substance) x Avogadro number

Mass of a molecule = Mole x Molar mass

= (Number of particles/ Avogadro number) x Molar mass]


Rajendra Prasad

6

Mass of a molecule = (Number of particles/ Avogadro number) x

Molar mass

= (3.011 x 10 24

molecules/ 6.022 x 10 23

molecules/mole) x 32 g/ mol =

180g.

Anions and Cat Ions

Atoms are normally electrically neutral because they have the same

number of protons (positively charged) as electrons (negatively charged).

However, if it gains or losses one or more electrons, an atom becomes

electrically charged. Some atoms easily gain one or more electrons and

others lose one or more electrons to have stable electronic structure; and

become electrically charged giving anion or cation.

Those that gain electrons become negatively charged and are called

anions, and those atoms that lose an electron become positively charged

and are called cat ions.

In short, it may be said that an ion is a charged chemical particle. An

ion carrying positive charge is called cation whereas an ion carrying

negative charge is called anion; and a group of two or more atoms

carrying charge is called polyatomic ion.

Valency table for some cations:

Monovalent cations

Valency = +1

Divalent cations

Valency = +2

Trivalent cations

Valency = +3

Hydrogen H+ Magnesium Mg2+ Aluminium Al+3

Lithium Li+ Calcium Ca2+ Chromium Cr+3

Sodium Na+ Barium Ba+2 Bismuth Bi+3

Potassium K+ Zinc Zn+2 Antimony Sb+3

Silver Ag+ Copper Cu+2 Ferric Fe+3

Ammonium NH4+ Ferrous Fe2+ Phosphorous P+3



7

Valency table for some anions

Monovalent anions

Valency = -1

Divalent anions

Valency = -2

Trivalent anions

Valency = -3

Fluoride F- Oxide O-2 Nitride N-3

Chloride Cl- Sulphide S-2 Borate BO3-3

Bromide Br- Sulphate SO4-2 Phosphide P-3

Iodide I- Sulphite SO3-2 Phosphate PO4

-3

Hydroxide OH- Carbonate CO3-2 Arsenite AsO-3

Cyanide CN- Oxalate C2O2-2 Arsenate AsO4

-3

Nitrate NO3- Dichromate Cr2O7

-2 Antimonide Sb-3

Nitrite NO2- Chromate CrO4

-2 Boride B-3

Bicarbonate HCO3- Hydrogen phosphate HPO4

-2 Phosphite PO3-3

Permanganate MnO4- Hyposulphite SO2

-2 Hypophosphite PO2-3

Elementary Idea of Atomic Structure

In chemistry atomic theory is a scientific theory of the nature of matter,

which states that matter is composed of discrete units called atoms. It

began as a philosophical concept in ancient Greece and entered the

scientific mainstream in the early 19th century when discoveries in the

field of chemistry showed that matter did indeed behave as if it were

made up of atoms.

The word atom comes from the Ancient Greek adjective atomos,

meaning "uncuttable". The 19th century chemists began using the term in

connection with the growing number of irreducible chemical elements.

Around the turn of the 20th century, through various experiments with

electromagnetism and radioactivity, physicists discovered that the so-

called "uncuttable atom" was actually a conglomerate of various sub-

atomic particles namely electrons, protons and neutrons which can exist

separately from each other. Since atoms were found to be divisible,

physicists later invented the term "elementary particles" to describe the

"uncuttable", though not indestructible, parts of an atom. This may be

summarized as below:

Comparison of some atomic models:

Description Atomic

model No .I

Atomic

Model No. II

Atomic

model No.III

Name of the

model

Plum in

pudding model

Nuclear atomic

model

Orbit and energy

shell model


Rajendra Prasad

8

Proposed by J.J. Thomson Ernest

Rutherford

Niels Bohr

Description of the

model

Atom consists

of a sphere of

positive

electricity in

which electrons

are embedded

like plums in a

pudding.

An atom

consists of

massive

positively

charged nucleus

around which

the electrons are

moving.

Electrons are

moving around the

nucleus in definite

circular paths

called orbits or

energy shells.

Limitations of the

model

This model is

not able to

explain the

observations of

alpha-particle

experiment.

This model is

not able to

defend the

spiral fall down

of moving

electron in the

nucleus.

This model is not

sufficient to

explain the dual

nature of electron.

Modification in

the model

It was modified

by Rutherford

in the form of

nuclear atomic

model.

It was modified

by Bohr in the

form of orbit

model.

It was modified in

the light of works

of the scientists

such as de Broglie,

Heisenberg and

Schrodinger and

wave mechanical

model was

proposed.

Thus atom is a smallest unit of a matter which consists of electrons,

protons and neutrons

Dalton’s Atomic Theory andAvogadro’s Hypothesis

Dalton’s Atomic Theory – Dalton states that a matter is composed of

very small in-indivisible practices, called ATOMS. According to

Dalton‘s atomic theory:

1. The chemical elements are made up of very minute particles of

matter called atoms which do not suffer any division in any chemical

change.

2. Each kind of atom has a definite weight. Different elements have

atoms of different weights.



9

3. All atoms of the same elements are exactly alike, but they differ from

the atoms of all other elements.

4. The chemical compounds are formed by the union of the atoms of

one element with the atoms of another or other elements in sample

numerical ratio.

Dalton further stated that whenever two or more than two atoms

combine, they do so always in a simple ratio.

Dalton estimated the atomic weights according to the mass ratios in

which they combined, with the hydrogen atom taken as unity. However,

Dalton did not conceive that with some elements atoms exist in

molecules—e.g. pure oxygen exists as O2. He also mistakenly believed

that the simplest compound between any two elements is always one

atom of each (so he thought water was HO, not H2O).This, in addition to

the crudity of his equipment, flawed his results. For instance, in 1803 he

believed that oxygen atoms were 5.5 times heavier than hydrogen atoms,

because in water he measured 5.5 grams of oxygen for every 1 gram of

hydrogen and believed the formula for water was HO. Adopting better

data, in 1806 he concluded that the atomic weight of oxygen must

actually be 7 rather than 5.5, and he retained this weight for the rest of

his life. Others at this time had already concluded that the oxygen atom

must weigh 8 relative to hydrogen equals 1, if one assumes Dalton's

formula for the water molecule (HO) or 16 if one assumes the modern

water formula (H2O).

Avogadro’s Hypothesis: Berzelius introduced another hypothesis after

studying Dalton‘s and Gallussac‘s laws that equal volume of all gases

should contain equal number of atoms at STP. On verification, this was

found that according to Berzelius atom is divisible which was contrary to

Dalton‘s Atomic theory.

The Avogadro suggested that equal volumes of all gases contain equal

number of molecule in place of atoms as states by Berzelius. On

verification Avogadro‘s law is found in support of Dalton‘s atomic

theory, hence, broadly accepted.

Avogadro suggested that matter is made up of two kinds of

fundamental practices called atoms and molecules.

Atom: Atom is the smallest particles of an element which may or may

not exist freely in nature but can take part in a chemical reaction. Atom

has got the chemical existence.

Example: H-atom, Cl-atom, Na-atom etc.

Molecule: Molecule is the physically existing smallest particle of an

element or a compound which can exist freely and possess all the


Rajendra Prasad

10

properties of that kind of matter. Example: N2 molecule, Cl2 – molecule,

H2 – molecule etc.

Discovery of Sub-atomic Particles

Thomson suggested that atoms were divisible, and that the corpuscles

(electrons) were their building blocks. To explain the overall neutral

charge of the atom, he proposed that the electrons were distributed in a

uniform sea of positive charge; this was the plum pudding models the

electrons were embedded in the positive charge like plums in a plum

pudding (although in Thomson's model they were not stationary).

Results of scientific researches by Thomson, Ruther Ford, and Bohr

etc of 20th century gave the better idea of an atom. According to their

results, it was found that atom consists of still smaller particles, called

electrons, protons and neutrons.

Electrons and protons are electrically charged where as neutrons are

electrically neutral particles.

Ruther Ford’s experiment - Ruther Ford bombarded a thin sheet of

gold with high speed positively charged α- particles and observed that

most of the α - particles passed in a straight line without deflection. Some

deflected to small angles and very few were sent back.

On the basis of above experiment he concluded the following results.



11

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