CHAPTER-1

BASIC CONCEPTS OF CHEMISTRY

Chemistry is a branch of science that involves the study of the composition,

structure and properties of matter.

Chemistry is important because everything you do is chemistry! Even your

body is made of chemicals. Chemical reactions occur when you breathe, eat,

or just sit there reading. All matter is made of chemicals, so the importance

of chemistry is that it's the study of everything

Matter is anything that has mass and takes up space. Matter requires at least

one subatomic particle, although most matter consists of atoms.

States of Matter- There are 3 States of Matter. Solids, Liquids and Gases

• Some Characteristics of Gases, Liquids and Solids

– Solid matter is composed of tightly packed particles. A solid will

retain its shape; the particles are not free to move around.

– Liquid matter is made of more loosely packed particles. It will take

the shape of its container. Particles can move about within a liquid,

but they are packed densely enough that volume is maintained.

– Gaseous matter is composed of particles packed so loosely that it

has neither a defined shape nor a defined volume. A gas can be

compressed.

• S.I UNITS - The units and their physical quantities are the second for

time, the metre for measurement of length, the kilogram for mass, the

ampere for electric current, the kelvin for temperature, the mole for

amount of substance, and the candela for luminous intensity.

Some important SI Units

• Derived SI Units with Special Names

• Frequency v, hertz

• force F newton

• pressure p pascal

• Energy joule

• Power P watt

• electric charge Q coulomb

Elements - Elements are chemically the simplest substances and hence

cannot be broken down using chemical reactions. An element is a substance

that is made entirely from one type of atom.

DIFFERENCE B/W COMPOUNDS AND MIXTURE

Compounds 1. Compounds are pure substances.

2. They are made up of two or more elements combined chemically.

3. The constituents of a compound are present in a fixed ratio.

4. Compounds have fixed properties. For example, a particular compound

will have fixed temperatures at which it melts and boils.

5. A compound can have properties different from its constituents, as a new

substance is formed when the constituents are chemically combined.

6. The constituents of a compound can be separated only by chemical

methods.

Mixtures

1. Mixtures are impure substances.

2. They are made up of two or more substances mixed physically.

3. The constituents of a mixture are present in varying ratios.

4. Mixtures do not have fixed properties. Their properties depend on the nature

of their components and the ratios in which they are combined.

5. In mixtures, no new substance is formed. The properties of a mixture are the

same as the properties of its constituents.

6. The constituents of a mixture can be separated easily physically.

SYMBOLS - A chemical symbol is a shorthand method of representing an

element. Instead of writing out the name of an element, we represent an

element name with one or two letters.

1. Tin- Sn

2. Lead- Pb

3. Gold- Au

4. Sulfur- S

5. Mercury- Hg

6. Silver- Ag

7. Iron- Fe

MOLECULAR FORMULA - A molecular formula consists of the

chemical symbols for the constituent elements describing the number of

atoms of each element present in the molecule.

EXAMPLE AgI silver iodide

Al2O3 aluminium oxide

BaCl2barium chloride

KBr potassium bromide

MgBr2 magnesium bromide

NaBr sodium bromide

NaI sodium iodide

ammonium chloride NH4Cl

sodium chloride NaCl

potassium chloride KCl

potassium nitrate KNO3

calcium hydroxide Ca(OH)2

Calculation of Molecular weight- Add atomic weight of all atoms present in

the molecular formula. Ex. H2O

H=1, O=16

2*1+16=18 amu

NaOH =23+16+1=40

CHAPTER-2

ATOMIC STRUCTURE

• An atom itself is made up of three tiny kinds of particles called

subatomic particles: protons, neutrons, and electrons. The protons and the

neutrons make up the center of the atom called the nucleus and the

electrons revolve around above the nucleus in a small cloud.

• An atom is the smallest constituent unit of ordinary matter that constitutes

a chemical element.

Electron,Proton and Neutrons

• Electron was discovered by J. J. Thomson in 1897.

• In 1909, Rutherford discovered proton in his famous gold foil

experiment.

• Atomic mass = mass of protons + mass of neutron.

• For a neutral atom, number of proton=number of electron.

• Measured masses and charges of the three elementary particles are given

in the following table.

• Particle Symbol Charge

• Electron e–

-1.60×10-19

C

• Proton p+ (H

+) 1.60×10

-19 C

• Neutron n0

0.00 C

Atomic representation

Z is used to signify the atomic number of an atom. Z = # of protons of an

atom. A is used to signify the atomic mass number (also known as atomic

mass or atomic weight) of an atom. A = # protons + # neutrons

Elements are represented by a chemical symbol, with the atomic number and

mass number sometimes affixed as indicated below. The mass number is the

sum of the numbers of neutrons and protons in the nucleus.

Bohr’s Atomic Theory

According to Bohr's theory , electrons revolve in definite circular orbits

around the nucleus and these orbits are designated by the letters K, L, M, N

or by the numbers 1, 2 ,3, 4 and so on.

• As long as the electrons revolve in a particular orbit they can neither gain

energy nor loose energy. Such orbits are called as stationary orbits or

stationary states.

• When an electron jumps from an higher orbit to a lower orbit it releases

energy in the form of radiations and when an electron jumps from lower

orbit to a higher orbit it absorbs energy in the form of radiations.

• The angular momentum of aln electron is an integral multiple of h/ 2π

mvr = nh/ 2π

• It explains the stability of an atom and also the line spectrum of hydrogen

atom.

Isotopes, Isobars and Isotones

Isotopes are two or more elements having the same number of protons but

different number of neutrons i.e having the same atomic number but

different mass number. Carbon 12 and Carbon 14 are both isotopes of carbon

Isobars are the elements having same mass number but different atomic

number. Eg. 40

S, 40

Cl, 40

Ar, 40

K, and 40

Ca.

Isotones are the elements that are having the same number of neutrons.

Aufbau Principle - The aufbau principle states that in the ground state of an

atom or ion, electrons fill atomic orbitals of the lowest available energy

levels before occupying higher levels. For example, the 1s subshell is filled

before the 2s subshell is occupied.

Hund's rule: every orbital in a subshell is singly occupied with one electron

before any one orbital is doubly occupied, and all electrons in singly

occupied orbitals have the same spin.

The Pauli Exclusion Principle states that no two electrons can have the

same quantum number, and thus, electrons in the same orbital must have

opposite spins.

Electron configuration- the electron configuration is the distribution of

electrons of an atom or molecule (or other physical structure) in atomic or

molecular orbitals.We follow the three important rules: Aufbau's Principle,

Pauli-exclusion principle, and Hund's Rule.

Some important electron configuration

Hydrogen (1H) – contains one electron. This electron will be

accommodated in the s orbital of K shell. Therefore, the accommodation

of this electron is written as 1s1 . The number before the orbital indicates

the main energy level the orbital is. The superscript is the number of

electrons accommodated by the orbital.

• the configuration of Li: 1s22s

1

• The electronic configuration of sodium is : 1s22s

22p

63s

1.

• the electronic configuration of K is 1s22s

22p

63s

23p

64s

1.

• Calcium (20Ca) – 1s22s

22p

63s

23p

64s

2

CHAPTER-3

CHEMICAL BONDING

A chemical bond is a lasting attraction between atoms, ions or molecules

that enables the formation of chemical compounds. The bond may result

from the electrostatic force of attraction between oppositely charged ions as

in ionic bonds or through the sharing of electrons as in covalent bonds.

Why do atoms combine?

Atoms combine together to lose their energy. This would make them stable.

Why do certain atoms combine while others do not?

This is mainly because a compound forms only when there is an attractive

force leading to the lowering of energy. On the other hand, in case of a

repulsive force, we find an increase in overall energy of the system. Thus,

we do not see the formation of any compounds.

Valence electron is an outer shell electron that is associated with an atom,

and that can participate in the formation of a chemical bond

In the Lewis symbol for an atom, the chemical symbol of the element (as

found on the periodic table) is written, and the valence electrons are

represented as dots surrounding it. Only the electrons in the valence level are

shown using this notation.

Octet rule - it states that every atom wants to have eight valence electrons in

its outermost electron shell. The octet rule explains how atoms of different

elements combine to form molecules. In a chemical formula, the octet rule

strongly governs the number of atoms for each element in a molecule; for

example, calcium fluoride is CaF2 because two fluorine atoms and one calcium

satisfy the rule.

Difference b/w orbit and orbital

An orbit on the other hand is simply present in a body with a certain mass,

while an orbital exists for an electron as well as an atom.

An orbit is the simple planar representation of an electron. An orbital refers

to the dimensional motion of an electron around the nucleus in a three

dimensional motion.

Electrovalent bonding - Electrovalent bonding or ionic bonding involves

the transfer of electrons between atoms. In such cases, one atom loses an

electron and the other atom gains an electron.When an electron transfer

occurs, one atom has a negative charge making it the anion. On the other

hand, the other atom has a positive charge making it the cation. The ionic

bond is majorly strong because of the concept of “opposite charges

attract.”

Covalent bonding - Covalent bonding is the most common method of

bonding in compounds containing carbon. These are basically the organic

compounds. A Covalent bond signifies the sharing of electrons between

atoms. In such cases, we know that there is a formation of a new orbit by

the shared pair of electrons. This orbit extends around the nuclei of both

the atoms and creates a new molecule.

Ionic Bonds Vs Covalent Bonds

Ionic Bonds Covalent Bonds

1 An ionic bond is formed

between a metal and a non-

metal. Non-metals(-ve ion)

are "stronger" than the

metal(+ve ion) and can get

electrons very easily from

the metal. These two

opposite ions attract each

other and form the ionic

bond.

Sodium chloride (NaCl),

Sulphuric Acid (H2SO4 )

Covalent bonding is a form of chemical bonding between two non metallic

atoms which is characterized by the sharing of pairs of electrons between

atoms and other covalent bonds.

Methane (CH4), Hydro Chloric acid (HCl)

2 No definite shape definite shape

3 Melting point is high Melting point is low

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CHAPTER-4

SOLUTIONS

• SOLUTIONS - A homogenous mixture of two or more substances in

relative amounts that can be varied continuously up to what is called the

limit of solubility. For example of salt water, the solute is the salt.

Solvent: this is the substance that makes up the majority of the solution.

This is the part where the solute is dissolved. In our example of salt

water, the solvent is water.

• A binary solution is a homogeneous mixture of two or more than two

substances whose composition can change within a certain limits. A

solution of two substances is called binary solution.

• An aqueous solution is a solution in which the solvent is water.

Solute and Solvent

• In a solution, the substance which gets dissolved is solute, whereas

solvent is the substance in which the solute will dissolve.

• Some examples of solvents are water, ethanol, toluene, chloroform,

acetone, milk, etc.

• Examples of solutes include, sugar, salt, oxygen, etc.

The concentration of a substance is the quantity of solute present in a

given quantity of solution. Unit is g/lt.

• Acids are substances that ionize in an aqueous solution to produce

hydrogen (H+) ions while bases produce hydroxide (OH

-) ions in solution

• Bases are the substance which dissociates in to hydroxide ion when

dissolve in water.

• Salt are the compoumd formed from an acid by the replacement of

hydrogen ion in the acid by a metal.

• Acid- HCl, H2SO4, HNO3, H3PO4 etc.

• Base- NaOH, KOH, Ca(OH)2 etc.

• Salts- NaCl, KCl, KNO3 etc.

• Acidity -the amount of H+ ions can be produced by a compound

determines the acidity. acidity increase with decrease in ph number.

• Basicity- the amount of OH- ion can be produced by a compound

determines basicity.

• Strength- strength of a solution is a measure of the concentration of ions

in that solution.

• Molarity -It is the number of moles of solute dissolved in one litre of a

solution.

• Molality- the concentration regarding moles of solute and the mass of

solvent. It is given by moles of solute dissolved per kg of the solvent. The

molality formula is as given-

• Molality(m)=Moles of solute/Mass of solvent in Kg

Normality - Normality is a measure of concentration equal to the gram

equivalent weight per liter of solution. Gram equivalent weight is the

measure of the reactive capacity of a molecule. The solute's role in the

reaction determines the solution's normality. Normality is also known as

the equivalent concentration of a solution.

The normality of a solution is the gram equivalent weight of a solute per

liter of solution. It may also be called the equivalent concentration. It is

indicated using the symbol N, eq/L,

Difference b/w Molarity & molality

• Molarity is a measurement of the moles in the total volume of the

solution, whereas molality is a measurement of the moles in relationship

to the mass of the solvent.

capital letter “M” to represent molarity while lower case letter “m” to

represent molality.

pH of solution

• The pH of a solution is a measure of the molar concentration of hydrogen

ions in the solution and as such is a measure of the acidity or basicity of

the solution.

• A measure of acidity or alkalinity of water soluble substances (pH stands

for 'power of Hydrogen').

• The pH scale usually ranges from 0 to 14. Aqueous solutions at 25°C

with a pH less than 7 are acidic, while those with a pH greater than 7 are

basic.

Applications of pH

• Pure water is neutral. When an acid is dissolved in water, the pH will be

less than 7 (25 °C). When a base, is dissolved in water, the pH will be

greater than 7. A solution of a strong acid, such as hydrochloric acid.

Measurements of pH are important in chemistry, agronomy, medicine,

water treatment, and many other applications.

• It is important for us to assist our body in creating and maintaining a

healthy pH ratio of 70:30, alkaline to acid. Most diseases, illnesses, and

bad bacteria thrive in an over acidic environment. When pH levels are

unbalanced, it is mostly in the case of being too acidic.

• pH plays a very important role in our everyday life. In our digestive

system : Hydrochloric acid produced in our stomach helps the digestion

of food without causing any harm to the stomach. But when the amount

of the acid goes beyond a certain limit due to indigestion, pain and

irritation are created in the stomach.

• PH meter, electric device used to measure hydrogen-ion activity (acidity

or alkalinity) in solution. Fundamentally, a pH meter consists of a

voltmeter attached to a pH-responsive electrode and a reference

(unvarying) electrode.

CHAPTER-5

ELECTROLYSIS

• Chemical decomposition produced by passing an electric current through

a liquid or solution containing ions.

• Electrolysis is a process that uses the power of electricity to split elements

and compounds.

• An electric current is passed between a negatively charged electrode

called a cathode and a positively charged electrode called an anode.

• Electrolytes are salts or molecules that ionize completely in solution. As

a result, electrolyte solutions readily conduct electricity.

• Nonelectrolytes do not dissociate into ions in solution; nonelectrolyte

solutions do not, therefore, conduct electricity. Example: Urea, Benzene,

Sugar, Ethanol, Chloroform , ether etc.

• During electrolysis, ionic substances are decomposed into simpler

substances when an electric current is passed through them.

ELECTROLYSIS and its Uses

• Electrolysis is used to extract and purify metals.

• Electrorefining - It is also used in refining of metals like copper.

• Electroplating.

Faraday's First Law of Electrolysis

The mass of the substance (m) deposited or liberated at any electrode is

directly proportional to the quantity of electricity or charge (Q) passed.

Faraday's Second Law

• It states that, “When the same quantity of electricity is passed through

different electrolytes, the masses of different ions liberated at the

electrodes are directly proportional to their chemical equivalents

(Equivalent weights).”

Applications of electrolysis

• Electrometallurgy is the process of reduction of metals from metallic

compounds to obtain the pure form of metal using electrolysis.

• Electroplating is commonly used for various purposes such as: the

bumpers of cars are chromium-plated and water taps being plated with

nickel or chromium to protect them from corrosion; ‘tin’ cans being only

iron plated with tin to prevent rusting; a ‘silver’ spoon being electroplated

for decoration

CHAPTER-6

Metallurgy

• Metallurgy, art and science of extracting metals from their ores and

modifying the metals for use.

• Metallurgy is used to separate metals from their ore.

• The compounds of metals mixed with soil, limestone, sand, and rocks are

known as minerals. Metals are commercially extracted from minerals at

low cost and minimum effort. These minerals are known as ores.

Types of metallurgy

1. Hydrometallurgy

2. Pyrometallurgy

3. Electrometallurgy

Gangue & Flux

• A substance which is added to the charge in the furnace to remove the

gangue (impurities) is known as flux.

• gangue are earthy impurities.

Principles of Metallurgy

The metallurgical process can be classified as the following:

1. Crushing and grinding: The first process in metallurgy is crushing of

ores into a fine powder in a crusher or ball mill. This process is known as

pulverization.

2. The concentration of ores: The process of removing impurities from ore

is known as a concentration of minerals or ore dressing. In metallurgy, we

concentrate the ores mainly by the following methods.

3. Hydrolytic method: In this method, we pour the ore over a sloping,

vibrating corrugated table with grooves. A jet of water is allowed to flow

over the surface. The denser ore particles settle in the grooves, and the

impurities are washed away by water.

4. Magnetic separation: In this case, the crushed ore is placed on a

conveyor belt. This belt rotates around two wheels in which one of the

wheels is magnetic, and therefore the magnetic particles get attracted to the

magnetic wheel and fall apart from the non-magnetic particles.

5. Froth floatation: In this process, we take the crushed ore in a large tank

which contains oil and water. A current of compressed air is passed through

it. The ore gets wet by oil and is separated from the impurities in the form of

froth. Ore is lighter, and so it comes on the surface and impurities are left

behind.

6. Roasting and calcination: In metallurgy, the process of heating a

concentrated ore in the presence of oxygen is known as roasting. This

process is applied in a case of sulfide ores. For ores containing carbonate or

hydrated oxides, heating is done in the absence of air to melt the ores, and

this process is known as calcinations.

• Roasting and calcination: In metallurgy, the process of heating a

concentrated ore in the presence of oxygen is known as roasting. This

process is applied in a case of sulfide ores. For ores containing carbonate

or hydrated oxides, heating is done in the absence of air to melt the ores,

and this process is known as calcinations.

• Smelting is to extract (metal) from its ore by a process involving heating

and melting. Example-"tin smelting"

• Electrolytic reduction- The electrolytic reduction is a type of

electrolysis. The oxides , hydroxide and chlorides of metals in fused state

are electrically reduced by using this method. The metals are extracted at

the cathode . Certain metals like Na , K, Mg , Ca , Al are obtained by

electrolytic reduction process.

• Electrolytic refining, is a technique used for extraction, as well as

purification, of metals obtained by any refining method. In the electro-

refining process, a block of impure metal becomes the anode, and a thin

sheet of metal becomes the cathode.

• An alloy is a combination of metals or a combination of one or more

metals with non-metallic elem.

• Alloys are metallic compounds composed of one metal and one or more

metal or non-metal element. Examples of common alloys: Steel, a

combination of iron (metal) and carbon (non-metal) Bronze, a

combination of copper (metal) and tin (metal) and. Brass, a mixture of

copper (metal) and zinc (metal)

• Alclad: aluminum sheet made by bonding high-purity aluminum to a

high strength core material.

• Al-Li (lithium, sometimes mercury)

• Alnico (aluminum, nickel, copper)

• Duralumin (copper, aluminum)

• Magnalium (5% magnesium)

Purpose of alloy formation

1. Alloys are made to: Enhance the hardness of a metal: An alloy is harder

than its components. Pure metals are generally soft.

2. Alloying a metal increases the inertness of the metal, which, in turn,

increases corrosion resistance.

3. This makes the metals easily fusible.

4. Alloy formation increases the tensile strength of the parent metal.

Steel is an alloy of iron and carbon, and sometimes other elements. Because

of its high tensile strength and low cost, it is a major component used in

buildings, infrastructure, tools, ships, automobiles, machines, appliances, and

weapons. Iron is the base metal of steel.

Stainless steels are alloys that are made up of iron and generally contain

around 11.5% chromium. Stainless Steel is more resistant to corrosion

than Carbon Steel.

CHAPTER-7

FUELS

• A fuel is a substance which gives heat energy on combustion. A fuel

contains carbon and hydrogen as main.

• There are three types of fossil fuels which can all be used for energy

provision; coal, oil and natural gas. combustible elements

• Solid Fuels

• Solid fuel refers to various types of solid material that are used as fuel to

produce energy and provide heating,

• Types of solid fuel

Wood, Coal, Straw and Charcoal.

• Liquid Fuels

• Liquid fuels like furnace oil and are predominantly used in industrial

applications.

• ethanol, jet fuel and biodiesel which are all categorized as a liquid fuel.

• Types of liquid fuel

• Petroleum

Oils from distillation of petroleum

Coal tar

Shale-oil

Alcohols, etc.

• The amount of energy produced by the complete combustion of a

material or fuel. Measured in units of energy per amount of material, e.g.

kJ/kg.

• Higher Calorific Value (HCV) -When 1 kg of a fuel is burnt, the heat

obtained by the complete combustion after the products of the

combustion are cooled down to room temperature.

• Lower calorific value (LCV)- the amount of heat evolved when a unit

weight of the fuel is completely burnt and water vapor leaves with the

combustion products without being condensed.

An ideal fuel should have the following properties:

• High calorific value.

• Moderate ignition temperature.

• Low moisture content.

• Low NOn combustible matter.

• Moderate velocity of combustion.

• Products of combustion not harmful.

• Low cost.

• Easy to transport.

Advantages of gas fuel over solid fuel

• gaseous fuels are easier to handle than solid fuels.

• gaseous fuels can be transported easily through pipelines whereas solid

fuels cannot be transports in this way.

• gaseous fuels do not leave any residue after burning.

• gaseous fuels have higher calorific values than the solid fuels. In other

words, for a given mass of the fuel, liquid and gaseous fuels produce

more heat.

• gaseous fuels produce little or no smoke, whereas most of the solid fuels

burn with smoke.

• gaseous fuels have relatively low ignition temperature and hence they

burn more easily than solid fuels.

• Proximate Analysis is a partitioning of compounds in a feed into six

categories based on the chemical properties of the compounds. Proximate

analysis includes the moisture, ash, volatile matter, and fixed carbon

contents of tests, collectively called the proximate analysis, that

determine the moisture content, volatile matter content, ash content,

fixed-carbon content, and calorific value of a coal.

Importance of proximate analysis of coal - Proximate analysis of a

fuel provides the percentage of the material that burns in a gaseous state

(volatile matter), in the solid state (fixed carbon), and the percentage of

inorganic waste material (ash), and is therefore of fundamental

importance for biomass energy use. It is important and the amount of

fixed carbon contains more carbon and has a high calorific value.

• LPG - Liquefied petroleum gas or liquid petroleum gas also referred to

as simply propane or butane, are flammable mixtures of hydrocarbon

gases used as fuel in heating appliances, cooking equipment, and

vehicles.

• CNG- Compressed natural gas (CNG) (methane stored at high

pressure) is a fuel which can be used in place of gasoline (petrol).

• Biogas is the mixture of gases produced by the breakdown of organic

matter in the absence of oxygen. Biogas can be produced from raw

materials such as agricultural waste, manure, municipal waste, plant

material, sewage, green waste or food waste. Biogas is a renewable

energy source.

Composition - Biogas is primarily methane CH4 and carbon

dioxide(CO2) and may have small amounts of hydrogen sulfide (H2S),

moisture. The gases methane, hydrogen, and carbon monoxide (CO) can

be combusted or oxidized with oxygen. This energy release allows biogas

to be used as a fuel; it can be used for any heating purpose, such as

cooking. It can also be used in a gas engine to convert the energy in the

gas into electricity and heat.

Advantages of Biogas

1. It's a Clean & Renewable Energy Source.

2. It Reduces Soil & Water Pollution.

3. Prevents Health Problems & Biodiversity Loss.

4. Generates Organic Fertilizer.

5. It's A Simple and Low-Cost Technology

FUEL RATING

• fuels rating is done by defining two parameters called Octane number and

Cetane number.

• Octane number- Octane rating is a measure of a fuel's ability to resist

'knock.' The octane requirement of an engine varies with compression

ratio, geometrical and mechanical considerations, and operating

conditions. The higher the octane number, the greater the fuel's resistance

to knocking or pinging during combustion.

• The octane rating is a measure of the resistance of gasoline and other

fuels to detonation (engine knocking) in spark-ignition internal

combustion engines.

• High-performance engines typically have higher compression ratios and

are therefore more prone to detonation, so they require higher octane fuel.

• Octane numbers are based on a scale on which isooctane is 100 (minimal

knock) and heptane is 0 (bad knock).

Cetane number (cetane rating) is an indicator of the combustion speed

of diesel fuel and compression needed

a measure of the ignition value of a diesel fuel that represents the

percentage by volume of cetane in a mixture of liquid methylnaphthalene

that gives the same ignition lag as the oil being tested for ignition.

CHAPTER -8

WATER

Water is a transparent, tasteless, odorless, and nearly colorless chemical

substance, which is the main constituent of Earth's streams, lakes, and oceans.

The water in our bodies is essential for life. Without water, we can't survive. ...

Water is involved in every bodily function from digestion and circulation

through to the control of body temperature and the excretion of waste products.

Sources of Water- There are two main sources of water: surface water and

groundwater. Surface Water is found in lakes, rivers, and reservoirs.

Groundwater lies under the surface of the land, where it travels through and fills

openings in the rocks.

Purest Sources of Water- Rain water is considered the purest form of water.

Impurities and salts present in water on earth are left behind during vaporisation

by the sun.

Impurest Sources of Water- Sea Water : It is the most impure form of natural

water. All impurities from river water are carried into the sea.

Types of Water- Soft and Hard water

Soft water- Soft water is surface water that contains low concentrations of ions

and in particular is low in ions of calcium and magnesium. Soap lathers better in

soft water than in hard water,

Hard water. - is water that contains an appreciable quantity of dissolved

minerals (like calcium and magnesium) dissolve in it. Calcium and magnesium

dissolved in water are the two most common minerals that make water "hard."

The degree of hardness becomes greater as the calcium and magnesium content

increases and is related to the concentration of multivalent cations dissolved in

the water.

Types of Hard water - There are two types of water hardness, temporary and

permanent.

Hardness is defined as the concentrations of calcium and magnesium ions

expressed in terms of calcium carbonate.

Temporary hardness - Temporary hardness is water hardness due to the

presence of calcium and magnesium carbonates and bicarbonates,

which can be precipitated by heating the water. It can be removed

by processes such as boiling or lime softening, and then separation

of water from the resulting precipitate.

Permanent. hardness - Permanent hardness in water is hardness due to the

presence of the chlorides, nitrates and sulphates of calcium and magnesium,

which will not be precipitated by boiling

The difference between temporary hardness and permanent hardness :-

The difference between the temporary hardness and permanent hardness in

water is that the temporary hardness is caused due to the bicarbonates of

calcium and magnesium ions. ... Whereas Permanent hardness in the water is

caused due to the sulphates and chlorides of calcium and magnesium.

Disadvantages of Hard Water- In domestic use:

(i) Washing: Hard water, when used for washing purposes, does not lather

freely with soap. On the other hand, it produces sticky precipitates of calcium

and magnesium soaps. The formation of such insoluble, sticky precipitated.

(ii) Bathing: Hard water does not lather freely with soap solution, but produces

sticky scum on the bath-tub and body. Thus, the cleansing quality of soap is

depressed and a lot of it is wasted.

(iii) Cooking: Due to the presence of dissolved hardness-producing salts, the

boiling point of water is elevated. Consequently, more fuel and time are

required for cooking.

(iv) Drinking: Hard water causes bad effect on our digestive system. Moreover,

the possibility of forming calcium oxalate crystals in urinary tracks is increased.

Industrial use- If the hard water is fed directly to the boilers, there arise many

troubles such as: (i) scale and sludge formation, (ii) corrosion,(iii) priming and

foaming and (iv) caustic embrittlement.

Scale and sludge formation - Boiler scale is caused by impurities being

precipitated out of the water directly on heat transfer surfaces or by suspended

matter in water settling out on the metal and becoming hard and adherent. Scale

is formed by salts that have limited solubility but are not totally insoluble in

boiler water.

Sludge is a semi-solid slurry and can be produced as sewage sludge from

wastewater treatment processes or as a settled suspension obtained from

conventional drinking water treatment and numerous other industrial processes.

Caustic embrittlement - Caustic embrittlement is the phenomena in which the

material of a boiler becomes brittle due to the accumulation of caustic soda. As

water evaporates in the boiler, the concentration of sodium carbonate increases

in the boiler. It cause damage to boilers.

Action of soap with hard water- The formation of such insoluble, sticky

precipitated continues, till all calcium and magnesium salts present in water are

precipitated. After that, the soap (e.g., sodium stearate) gives lather with water.

Thus;

The characteristics of potable water

Potable water or improved drinking water, is water that is safe to drink or to use

for food preparation, without risk of health problems.

Characteristics of potable water are as follows:

i) Cleaned of Harmful Contaminants .

ii) It is transparent.

iii) It is odourless and colourless.

iv) It is harmless or free from disease causing bacteria.

CHAPTER -9

LUBRICANTS

A lubricant is a substance, used to reduce friction between surfaces in mutual

contact, which ultimately reduces the heat generated when the surfaces move.

Vegetable oils or synthetic liquids such as hydrogenated polyolefins, esters,

silicones etc

Lubrication is the control of friction and wear by the introduction of a friction-

reducing film between moving surfaces in contact.

Lubrication is the application of a lubricant), between moving surfaces in

contact in order to reduce friction and minimize heating while lubricant is a

substance used to reduce friction between objects or surfaces.

The correct lubricant helps maximize the life of your bearings and machinery,

therefore saving money, time, and manpower, thus making operations more

efficient and more reliable.

Lubricants are classified in several ways; these could be liquid, semisolid

(greases), and solids.

Dry lubricants or solid lubricants are materials that, despite being in the solid

phase, are able to reduce friction between two surfaces sliding against each

other without the need for a liquid oil medium. The two main dry lubricants are

graphite and molybdenum disulfide.

Liquid lubricants reduce friction and wear between two moving or sliding

metallic surfaces by providing a continuous fluid film in between them. They

act as a cooling medium, a sealing agent, and a corrosion preventor. Liquid

lubricants are classified into many types, depending on the type of base oil

used. Example- Vegetable oil and animal oil, Mineral oil from

petroleum,Blended oil, doped oil, or compound oil.

Semi-solid lubricants are a gel-like substance which reduced friction

between two moving surfaces. E.g.; greases, Vaseline, waxes. semi-solid

lubricants (Greases) Preparation. Greases are semi-solid lubricants

obtained by thickening of lubricating oil by the addition of metallic soaps.

Grease is generally used for: (1) Machinery that runs intermittently or is in

storage for an extended period of time. Because grease remains in place, a

lubricating film can instantly form. (2) Machinery that is not easily

accessible for frequent lubrication

Aquadag is a trade name for a water-based colloidal graphite.

Types of lubricants

Theories of Lubrication

Fluid film lubrication is the lubrication regime in which, through viscous

forces, the load is fully supported by the lubricant within the space or gap

lubricants

Solid Liquid semi-

solid

between the parts in motion relative to one another object (the lubricated

conjunction) and solid–solid contact is avoided.

o In hydrostatic lubrication, external pressure is applied to the

lubricant in the bearing to maintain the fluid lubricant film where it

would otherwise be squeezed out.

o In hydrodynamic lubrication the motion of the contacting surfaces

as well as the design of the bearing pump lubricant around the

bearing to maintain the lubricating film.

Boundary lubrication (also called boundary film lubrication): The

hydrodynamic effects are negligible. The bodies come into closer contact at

their asperities; the heat developed by the local pressures causes a condition

which is called stick-slip, and some asperities break off. At the elevated

temperature and pressure conditions, chemically reactive constituents of the

lubricant react with the contact surface, forming a highly resistant tenacious

layer or film on the moving solid surfaces (boundary film) which is capable of

supporting the load and major wear or breakdown is avoided.

Distinguish between thick film and boundary film lubrication

The difference between thick film and boundary film lubrication are as

follows-

Thick film Boundary film lubrication

It is also known as film or

hydrodynamic lubrication.

It is also known as thin film

lubrication.

In this case, the coefficient of friction

ranges from 0.001 to 0.03.

In this case, the coefficient of

friction ranges from 0.05 to 0.15.

The lubrication should have minimum

viscosity.

The lubricant should have more

oiliness.

The lubricant neither gets absorbed on The lubricants may be absorbed on

nor chemically reacts with a metallic

surface.

or chemically reacts with metallic

surfaces

The lubricating oil forms uniform film

of a thickness more than 10000A in

between two moving or sliding

surfaces.

The lubricating oil forms uniform

film of a thickness more than 1000A

in between two moving or sliding

surfaces.

The oil molecules are disoriented.

This lubrication is used in machines

working under high load and slow

speed.

This lubrication is used in machines

working under light and high speed.

Bearing, gears, tractor rollers, lathes,

railway track joints, concrete

mixture etc.

A good lubricant generally possesses the following characteristics:

A high boiling point and low freezing point (in order to stay

liquid within a wide range of temperature)

A high viscosity index.

Thermal stability.

Hydraulic stability.

Demulsibility.

Corrosion prevention.

A high resistance to oxidation

Viscosity - viscosity, is the fluid's resistance to flow, The viscosity of a

lubricant is closely related to its ability to reduce friction in solid body

contacts.

The SI unit of dynamic viscosity is the pascal-second. The CGS unit is called

the poise (P).

The viscosity index (VI) is an arbitrary, unitless measure of the change of

viscosity with temperature.

The term “oiliness” is defined as that property of lubricants by virtue of which

one fluid gives lower coefficients of friction (generally at slow speeds or high

loads) than another fluid of the same viscosity

Flash point and fire point: The flash point is the lowest temperature to which a

lubricant must be heated before its vapor, when mixed with air, will ignite but

not continue to burn. The fire point is the temperature at which lubricant

combustion will be sustained.

Cloud and pour point of lubricants - Pour point is the lowest temperature at

which the product continues to flow when it is cooling, without stirring. Cloud

point is the temperature at which components within the fluid under test

precipitate on cooling. Cloud and pour point characteristics are indicative of

low temperature behaviour of a product.

Pour point represents the lowest temperature at which oil is capable of flowing

under gravity. It is one of the important low-temperature characteristics of

high-boiling fractions. When the temperature is less than the pour point of a

petroleum product, it cannot be stored or transferred through a pipeline.

TAN - Total Acid Number (TAN) is a measure of acid concentration present in

a lubricant. The acid concentration of a lubricant depends on the presence of

additive package, acidic contamination, and oxidation by-products.

The aniline point is called the "aniline point temperature," which is the lowest

temperature (°F or °C) at which equal volumes of aniline and the oil form a

single phase.

Iodine value of lubricants - Iodine numbers are often used to determine the

amount of unsaturation in fatty acids. This unsaturation is in the form of double

bonds, which react with iodine compounds.

It is the measure of the degree of unsaturation of an oil, fat, or wax; the amount

of iodine, in grams, that is taken up by 100 grams of the oil, fat, or wax.

CHAPTER -10

POLYMERS

A polymer (poly-, "many" + -mer, "part") is a large molecule, or

macromolecule, composed of many repeated subunits.

A polymer is a chemical compound with molecules bonded together in long

repeating chains. Because of their structure, polymers have unique properties

that can be tailored for different uses. Polymers are both man-made and

naturally occurring.

Polyethylene, Poly(tetrafluoroethylene) , Poly(vinyl Chloride) .

A monomer is a molecule that is able to bond in long chains.

Polymerization - This linking up of monomers is called polymerization.

Polymerization is a process of reacting monomer molecules together in a

chemical reaction to form polymer chains or three-dimensional networks.

Degree of Polymerisation - The degree of polymerization, or DP, is the

number of monomeric units in a macromolecule or polymer or oligomer

molecule.

Polymers are of two types: naturally occurring and synthetic or man made.

Natural polymeric materials such as hemp, shellac, amber, wool, silk and

natural rubber have been used for centuries. A variety of other natural polymers

exist, such as cellulose, which is the main constituent of wood and paper.

Natural Rubber is an elastic substance obtained from the latex sap of trees.

Natural rubber is an addition polymer of monomer isoprene.

The list of synthetic polymers, roughly in order of worldwide demand, includes

polyethylene, polystyrene, polyvinyl chloride, phenol formaldehyde resin (or

Bakelite), neoprene, nylon.

Neoprene (also polychloroprene) is a family of synthetic rubbers that are

produced by polymerization of chloroprene. Neoprene exhibits good chemical

stability and maintains flexibility over a wide temperature range.

Nylon 66 ( nylon 6,6) is a type of polyamide or nylon. It, and nylon 6, are the

two most common for textile and plastics industries. Nylon 66 is made of two

monomers each containing 6 carbon atoms, hexamethylenediamine and adipic

acid

Classification of Polymers.

The most common way of classifying polymers is to separate them into three

groups - thermoplastics, thermosets, and elastomers. The thermoplastics can be

divided into two types - those that are crystalline and those that are amorphous.

ADDITION AND CONDENSATION POLYMERS

Addition Polymerization Condensation Polymerization

Monomers must have either a double

bond or triple bond

Monomers must have two similar or

different functional groups

Produces no by-products By-products such as ammonia, water

and HCl are produced

Addition of monomers results in

polymers

Condensation of monomers result in

polymers

The molecular weight of the resultant

polymers is a multiple of monomer’s

molecular weight

The molecular weight of the resultant

polymer is not a multiple of monomer’s

molecular weight

Lewis acids or bases, radical initiators

are catalysts in addition polymerization

The catalysts in condensation

polymerization are catalysts in

condensation polymerization.

Common examples of addition

polymerization are PVC, polyethene,

Teflon etc.

Common examples of condensation

polymerization are nylon, bakelite,

silicon, etc.

The main difference between addition and condensation polymerization is that

in addition polymerization the polymers are formed by the addition of

monomers with no by-products while in condensation polymerization polymers

are formed due to the condensation of two different monomers resulting in the

formation of small molecules such as HCl, water, ammonia, etc., as by-

products.

Thermoplastics and thermosetting plastics

Thermoplastics and thermosetting plastics are two separate classes of polymers,

which are differentiated based on their behavior in the presence of heat. The

material difference between the two is that thermoplastics can be remelted,

while thermoset plastics remain in a permanent solid state once hardened.

Difference Between Thermoplastic and Thermosetting Plastic

Thermoplastic

Thermosetting Plastic

Thermoplastic can be synthesized by the

process called addition polymerization.

Thermosetting plastics are

synthesized by condensation

polymerization.

Thermoplastic is processed by injection

moulding, extrusion process, blow

moulding, thermoforming process, and

rotational moulding.

Thermosetting Plastic is processed

by compression moulding, reaction

injection moulding.

Thermoplastics have secondary bonds

between molecular chains.

Thermosetting plastics have primary

bonds between molecular chains and

held together by strong cross links.

Thermoplastics have low melting point

and low tensile strength.

Thermosetting plastics have high

melting point and tensile strength.

Thermoplastic is lower in molecular

weight, compared to thermosetting plastic.

Thermosetting Plastic is high in

molecular weight.

Bakelite - Bakelite is a condensation polymer of phenol and formaldehyde. It is

a thermosetting phenol formaldehyde resin, formed from a condensation

reaction of phenol with formaldehyde. Bakelite has a low electrical

conductivity and high resistance to heat and chemicals. It is a thermosetting

polymer and has high strength and retains its shape after moulding. it is a poor

conductor of heat and electricity so it is used for making electric switches to

protect us from getting electric shocks.

Difference between PVC and Bakelite

Bakelite is a phenol-formaldehyde resin.It is hard and used in telephones,

electrical gadgets, jewelry to cooking equipment whereas PVC

(polyvinylchloride) is a soft, polymeric material that is found in abundance. It is

used in ceramic, wood, leather, paper, metal, and glass.

Importance of polymers in our daily life - Polymers are widely used advanced

materials, which are found almost in every material used in our daily life.

Starches, important sources of food energy derived from plants, are natural

polymers composed of glucose

The polymer called Polyethylene is used in plastic bags and film wraps.

Polyvinyl Chloride( PVC) is used in siding, pipes,flooring purposes.

The synthetic polymer Polystyrene is used in cabinets, petri dishes, CD cases,

plastic cutlery and in packaging.

Polyvinyl acetate is used in adhesives and latex paints

Poly(tetrafluoroethene) 'PFTE' Non-stick coatings for pans, containers for

laboratory substances.

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