Chemistry Notes for Class Ninth (by: Seetal Daas)

Chemistry Notes for
Class Ninth
2012
Compiled By: Seetal Daas
University Of Sindh Laar Campus @ Badin
Contact:seetal.daas@gmail.Com
Voice: 0333-3971809

Chemistry Notes for Class Ninth__________________________________________________
Complied by: Seetal Daas 1
1
CHAPTER 1 INTRODUCTION TO CHEMISTRY
Q1: What are the branches of chemistry?
Ans: The five branches of chemistry are as follows:
1-Organic chemistry:-Organic chemistry is the study of carbon containing substances and
the synthesis of such material. many consumer products are organic in nature.
2-Inorganic chemistry: Inorganic chemistry is the chemistry of element and their compounds
except those of carbon-hydrogen compounds and their derivatives.
3-Physical chemistry: Physical chemistry is the branch of chemistry which deals with the
forces and principles involved in the combination of atoms and molecules.
4-Analytical chemistry: Analytical chemistry is the study of method and techniques used to
determined the kind and quantity of various components in a given substance.
5-Biochemistry: Biochemistry is the chemistry of living organisms such as plants and
animals.
Q2: Define mass?
Ans: Mass:-The quantity of matter contained in a body is called its mass.
its S.I unit is "kilogram" and its symbol is "m".
Q3: Define volume?
Ans: Volume:- Space occupied by a body is known as volume.
its S.I unit is "m3" and its symbol is "v".
Q4: Define density?
Ans: Density:-It is define as ratio between mass and volume. Mass per unit volume is known as
density. Mathematically: d=
𝑚
𝑣
its S.I unit is kg/m3. density of solid and liquid usually expressed in g/cm3 and that of gases as g/dm3.
Q5: Define temperature?
Ans: Temperature:- Temperature is a measure of the intensity of heat. it is thus a measure of
the degree of hotness and coldness in a body.
Q6: Define specific gravity?
Ans: Specific gravity:- The specific gravity of a substance is the ratio of its mass to the mass
of an equal volume of water at a specified temperature.
Specific gravity = mass of substance
mass of an equal volume of water
specific gravity of a substance is a ratio between two same quantities and then fore has no unit.
Q7: Define element?
Ans: Element:- An element is defined as a substance in which all the atoms are chemically

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identical having same atomic number. for example: iron: silver: gold: copper: oxygen: hydrogen:
etc.
Q8: Define compound?
Ans: Compound:- A compound is pure substances which consist of two or more element
chemically combined in a fixed proportion by mass. Compound can be broken down by chemical
method.
for example: water(H2O); salt(NaCl).
Q9: Define mixture?
Ans: Mixture:-A mixture contains two or more element which can easily be separated by
physical method. the component does not lose its chemical properties.
for example: soil; rock; etc.
Q10: Define Valency?
Ans: Valency:-The chemical combining capacity of an atom or an element with another
element is called valency.
Q11: Define atom?
Ans: Atom:-It is the smaller particle of an element. it does not exist freely into nature. it is the
unit of an element involved in a chemical reaction.
Q12: Define molecule?
Ans: Molecule:- It is the combination of two or more atom. it can exist freely in the nature.
Q13: Define mole?
Ans: Mole:-The weight of an atom or a molecule expressed in grams is known as one mole.
Q14: Define atomic mass?
Ans: Atomic mass:-The atomic mass of an element is the average relative mass of the isotopes
of that element referred to the atomic mass of carbon which is taken as 12.0000 amu.
Q15: Define molecular mass?
Ans: Molecular mass:- The molecular mass of an element when it exists in the form of
molecular or of a compound is the average mass of the molecular as compound to one atom of
12C6.
Q16: Define gram atomic mass?
Ans: Gram atomic mass:- The weight of an atom expressed in gram is called gram atomic
mass. it is also called gram atom.
Q17: Define gram molecular mass?
Ans: Gram molecular mass:- The weight of molecule expressed in gram is called gram
molecular mass .it is also called gram molecule.

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Q18: Define Avogadro’s number (n)?
Ans: Avogadro’s number:-The number of particles contained in a mole is equal to 6.023*10
power 23 is known as Avogadro number.
Q19: Define low of constant composition with examples?
Ans: Low of constant composition:-Proust formulate the low of constant composition in
1799 as that every pure sample of a particular chemical compound contain the same element
combined in the same fixed proportion. it is also called the low of definite proportions.
Examples:
1, He obtained several samples of copper carbonate from different sources and also prepared it
through different methods in his laboratory. he found whatever source of method of preparation
was used, it always had the same proportion of copper, carbon and oxygen by mass.
2, He also mixed ten grams of lead with different amount of sulphur to make the grey solid lead
sulphide. he always found that the lead sulphide had the same fixed percentage of lead and
sulphur.
Q20: Define heterogeneous mixture?
Ans: Heterogeneous mixture: the mixture which do not have uniform composition
throughout their mass, are called heterogeneous mixture.
Q21: Define homogenous mixture?
Ans: Homogenous mixture: mixtures having uniform composition are called homogenous
mixture.
Q22: Differentiate between compound and mixture?
Ans:
Compound Mixture
1:it is a pure substance. 1:it is an impure substance.
2:it cannot be separated by physical methods.
2:it can be separated into its components
by simple physical methods.
3:element forming compound lose their original
properties-s.
3:substance making up the mixture do
not lose their original properties.
4:its composition is fixed. 4:its composition is not fixed.
5:the melting point and boiling point of compound are
sharp and characteristic of each compound.
5:the melting point and boiling point of
a mixture are not sharp.

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CHAPTER 2 CHEMICAL REACTIONS AND CHEMICAL EQUATIONS
Q1: State law of conservation of mass (matter)? Give examples.
Ans.: During any process, mass is neither created nor destroyed this law was put forward by a
French chemist, Lavoiser in 1785.
This law states that:
Matter is neither created nor destroyed during a chemical reaction.
During a chemical reaction, the total mass of the product is equal to the total mass of the
reactants.
Example no 1:
When a piece of iron is left in moist air its surface gradually turns brown, the object gets rusted
and gains mass.
4Fe+3O2 2Fe2O3
The increase in mass is just the mass of oxygen.
Example no 2:
When coal burns it leaves behind ash. The ash is lighter than coal. But the mass of coal will be
equal to that of ash and the liberated carbon dioxide.
C+O2 CO2
Q2: state exothermic and endothermic reaction with examples?
Ans: Exothermic reaction:-Reaction in which heat energy is evolved is known as exothermic
reaction in such reaction the system become warmer and neat potential energy of substances
decreases. The enthalpy of product is less than the enthalpy of reactants.
Examples:-
When unslaked calcium oxide is added to water. The water becomes warm with formation of
Slakeel time . In this reaction heat energy is released.
Endothermic reaction:-Reaction in which heat energy is absorbed is known as endothermic
reaction. in such reaction enthalpy of reactants is lower than those of product. Since energy
Is absorbed during reaction the temperature of reaction decreases. (Example are)
Heat is absorbed in the decomposition of calcium carbonate. In this reaction heating must be
continuous to decompose calcium carbonate.
Q3: What are different types of reaction? Give chemical reaction of each type?
Ans: Chemical reaction are of following types:
1: Simple decomposition :-In this reaction a single compound is decomposed into two or
more simple substance.
2: Synthesis:-In this reaction two or more substance combines to form a single compound it is
also known as addition reaction.
3: Displacement:-In this reaction an atom or radical displaced by another in a compound. Such
reaction depend upon the electropositive or electronegative nature of an atom or radical to
displaced another.

5
4: Double decomposition / displacement :-In this reaction the two reactants decomposed
to form two new substances by exchanging their radicals.
5: Neutralization:-In this reaction , the hydrogen ion of an acid neutralized by the hydroxide
ion of a base to from salt and water.
6: Hydrolysis:-In this reaction the salt of both weak acid and base dissolve in water to from
acid and base.

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CHAPTER 3 WATER AND SOLUTION
Q1) Define solubility what are the factors which can affect solubility?
Ans: Solubility:-"The solubility of a solute in a solvent at a particular temperature is the
number of grams of solute necessary of saturate 100g of the solvent at that temperature."
Factore of solubility
1)Temperature:-It is often observed solubility of many solute the solution generally increases
in temperature for example, the solubility of potassium midrate increases with temperatures the
solubility of some solute decreases with the increase in temperature such solute generally heat
when dissolved in water for example, calcium oxide is less soluble in hot water than in the cold
state.
gases are also more soluble in cold solvent than in hot solvent.
2) Pressure:-Solubility of gases increases with the increase in pressure , carbon di oxide in filled in soda water
bottles pressure.
3) Nature of the solute and the solvent:-The solubility of polar compound is more in polar
solvent and that of non-polar solvent in non-polar solvent.
Q2) Define molarity?
Ans: Molarity:-Morality is a measure of the concentration of solution. It is denoted by "M"."It
is define as the number of moles of solute dissolved per liter of solution(not solvent)".
M= number of mole of solute
volume of solvent in dm3(L)
Q3) What are electrolysis and non-electrolysis also give example of strong and
weak electrolysis?
Ans: Electrolysis: The substance which allow electricity to pass through their solution and are
chemical decompose are called "electrolysis."
Example: acid, base, salt
Non-electrolysis:-" These substances which do not dissociate into ions when dissolved in
water and do not conduct electricity are known as non-electrolysis."
Example: sugar, solution, benzene.
Strong electrolysis:-Those electrolysis which are highly dissociated and can conduct large
current are known as “strong electrolysis".
Example: HCl, NaOH
Weak electrolysis: Those electrolysis which are poorly dissociated and can conduct poor
current are known as “weak electrolysis".
Example: acetic acid, mercuric chloride
Q4)Define electrolysis? Explain the process of electrolysis of copper chloride
solution?
Ans: Electrolysis: The movement of ion of an electrolyte and their deposition as neutral

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species at the electrodes under the influence of electric current is known as "electrolysis".
The electrolysis of aqueous copper chloride: When aqueous copper chloride is
electrolyzed between carbon electrodes copper is deposited at the cathode(negative electrode) &
chlorine is given at the anode(positive electrode).
Aqueous copper chloride contain copper ion and chloride ion. The copper ion behind
positively charged move towards the cathode and the chloride ion behind negatively move
towards the anode. The copper ion take up electrons from the cathode and deposit copper on it.
Reaction at cathode: Cu++(aq) +2e-Cu(s)
Reaction at anode: 2Cl-(aq) Cl2 + 2e-
Q5) Define saturated, unsaturated and super saturated?
Ans: Saturated: A saturated solution is the solution which contains maximum amount of solute
that it can dissolve at a particular temperature.
Unsaturated: An unsaturated solution is one which contains less amount of solute that it can
held at a particular temperature.
Super saturated: A super solution is one which contains more solute that it can theoretically
be held by the solvent at a particular temperature.
Q6) What do you mean by hard water and soft water?
Ans: Soft water:-Water which produces lathers with soap easily and do not produce insoluble
curdy precipitate is called soft water.
Hard water:-Water which produces insoluble curdy precipitate with soap and lather is not
easily formed is called hard water.

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CHAPTER 4 ACID, BASES AND SALT
Q1) What are acid? describe various concept of acid? Name five properties of
acid with equation?
Ans: Acid:-Those substance which provide H+ ion in aqueous solution are known as
"acid".
Concept of acid:-many scientist proposed different theories about acid. Some of the important
theories are given below.
Arrhenious theory:-A Sweedish scientist Arhenious define acid as "The substance which
give hydrogen ion in water".
Lowry and bronsted theory:-In 1923 Lowery Bronsted define acid as “The substance
which donate or trend to donate a proton.
In this example acidic. Accept donate proton to water which accept it.
Lewis theory:- In American scientist named Lewis in 1923 give an electronic definition about
acid according to him "acid is that substance which can accept alone pair of electron".
example: AlCl3,BF3 and H3O
can act of Lewis acid because aluminum is short of two electron for completion of its valency
shell and accepting it.
Properties of acid:
Physical properties:
1) They have sour taste.
2) They can turn blue litmus red.
3) Aqueou solution of acid conduct electricity.
Chemical properties:
1) When an acid react with metal it produces salt and hydrogen gas.
2) When an acid react with metal oxide it produce salt and water.
3) When an acid react with base it produce salt and water.
Q2) What are base? Describe various concept of base? name five properties of
base with equation?
Ans: Base:-Those substance which yield hydroxyl ion in aqueou solution are known as "base".
Concept of base:- Important concept of base are as follows:
Arrhenious theory:- The substance which give hydroxyl ion in water is known as base.
Lowry and bronsted theory:-Base is a substance which accepts or tend to accept a proton
in a chemical reaction dissociation of HCl may be represented as
Here HCl act as an acid of water as a base.
Lewis theory:-A base is that substance which can donate alone pair of electron. Ammonia is a
base because it donate electron pair of AlCl3.
Properties of base
Physical properties:-

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1) They have bitter taste.
2) They turn red litmus blue.
3) They conduct electricity.
Chemical properties:-
1)When base react with an acid it produce salt and water.
2) Base give ammonia gas when they are reacted with ammonium salt.
3) It react with aluminum to form sodium aluminate and hydrogen gas is evolved.
Q3) What is Ph scale?
Ans:- PH:-PH is defined as the logarithm of reciprocal of hydrogen ion concentration.
PH= 1
H
Q4) Define following item strong and weak acid and base, neutralization ,acidity
of base and basicity of acid and crystallization?
Ans: Strong acid:- Those acid which have high percentage (more than 30 percentage) are
strong acid.
Example: HCl, HNO3 etc.
Weak acid:- Those acid which have low percentage of dissociation (less than 30 percentage)
are weak acid.
Example:- HCN, CH3COOH etc.
Strong base:- Those acid which have high percentage of dissociation (more than 30
percentage) are strong base.
Example:- NaOH, KOH etc.
Weak base:-Those acid which have low percentage of dissociation (less than 30 percentage)
are weak base.
Example: NH4OH, Al(OH)3 etc.
Neutralization:-This reaction between acid and base resulting information of a salt and water
is called neutralization. During neutralization H+ and OH- ions which are responsible for
characteristic of acid and base combine to form unionized water molecule.
example: H+ +OH- H2O
Acidity of base:-The number of hydroxyl ions presents in a molecule of base for example
KOH is mono acid base Ca(OH)2 is a di-acid base where as is tri-acid base.
Basicity of acid:- The number of replaceable or ionizable hydrogen atoms in the molecule of
an acid is called basicity of the acid.
Crystallization:- Crystal is a solid which possesses a definite geometrical shaped and the
process by which there crystal are prepared is called crystallization.

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CHAPTER 5 THE PERIOD TABLE
Q1: Write down the general characteristic group of IA, VIIA and VIIIA?
Ans: Group IA(ALKALI METAL): The alkali metals lithium, sodium, potassium,
rubidium, cesium and francium are light metal. They are very reactive and chemically are
strongly electropositively. As the group is descending there is a gradual decrease in ionization
potential with an increase in the size of the atom. They contain one electron in their outer most
shell and form ionic bonds by loss of valence electron. Compound of these metal were obtained
from wood ashes.
Group VIIA(HALOGEN FAMILY):- Flourine, chlorine, bromine and iodine constitute a
group or family of element called the halogen, a term which means "salt forms". The halogen are
very active non-metal and are very much a like in their chemical properties. Each of the halogen
has seven valence electron. Halogen are highly electronegative element and their electro-
negatively decrease down the group. Flourine and chlorine are gases at ordinary temperature
bromine is a liquid and iodine is a solid. all the halogen exit as diatomic molecule.
Group VIIIA(NOBLE GASES):-The element of group VIIIA are called "noble gases" or
"inert gases" or "zero gases" element. They are monoatomic and low boiling gases. Since the
outermost shell of these element are complete therefore these element are mostly chemically
unreactive. All the noble gases except radon are normally present in the atmosphere. They are
mostly obtained from air by liquefaction process.
Q2) What are transition element write four properties of them?
Ans: Transition element: Element of group IB, IIB, through VIIB are known as transition
element. They include the element scandium, yttrium, thanum and actinium and the two rare-
earth series of element the lantanide and actinide series.
properties:
(1) These element have incomplete inner electron shell.
(2) All transition element are metal.
(3) The bond between the atom are very strong and they have melting points.
(4) These compound are formed by coordinate covalent bond.

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CHAPTER 6 ATOMIC STRUCTURE
Q1: Describe the postulates of Dalton atomic theory? What are the draw backs
in this theory?
Ans: Dalton atomic theory:-The fundamental postulates of Dalton atomic theory are stated
below:
1) Matter is composed of extremely tiny invisible particles called atom.
2) Atom can neither be created or destroyed.
3) Atom of a particular element are identical in size shape mass and all other properties & differ
from atom of other element in these properties.
4) Chemical combination takes place between small whole number of atom.
According to the latest research on the structure of atom &matter neutral particle following
defect are observed in Dalton atomic model.
Drawbacks of Dalton atomic theory:-
1) Atom consist of charged particle called proton and electron & neutral particle called neutron.
2) The atom of the same element may differ in their atomic mass and such atom of an element
are called isotopes.
3) The ratio between atom of various element in many molecules of the organic compound is not
simple.
4) Matter can be converted into energy by Einstein equation E=mc2
Q2: How was electron discovered? describe in detail the experiment performed
for the discovery of electron?
Ans: Discovery of electron:-Electron is the smallest particle of atom. The most convincing
evidence for the existence of electron came from the experiment performed by Crookers,
Faraday, and J.J Thomson. A high voltage electric current was pass through gases at a very low
pressure(1mm of hg) in a dis charge tube. When high voltage is applied across the two metallic
electrode sealed in a discharge tube the rays begin to originate from cathode which are called
cathode ray. These rays travel in straight line towards the anode. If an electric field is applied ,
these rays bend towards the positive pole which show their negative nature.
Properties of cathode rays:-
1) Cathode rays travel in straight line away from the cathode.
2) Cathode rays are negatively charged as they bend towards the positive pole of the magnetic
field.
3) The rays upon striking glass or certain other material cause these material to glow.
4) The charge to mass ratio (e/m) of those particle was found equal to that of electron.
e/m = 1.76 * 10 power8 coulomb per gram
5) The mass of each negative particle was found equal to 1/1837 of the lightest Hydrogen atom.
On the basic of those properties it was concluded that cathode rays are negatively charged
particle called electron.

12
Q3: Discuss Bohrs atomic model &describe its significance in atomic structure?
Ans: Bohrs Atomic Model:- Neil Bohr proposed a new model for the structure of the atom in
1913.The salient features’ of this model are that.
1) Electron revolves around the nucleus in fixed circular paths which he called orbit or energy
level.
2) As long as an electron revolve in a particular energy level it does not emit or absorb energy.
3) When an electron absorbs energy it moves to a higher energy level further away from the
nucleus. When it lose energy it return to lower energy level closer to the nucleus & the energy is
emitted as light.
4) The electron loses a definite quantity of energy called quantum of energy when it jump down
from an orbit of higher energy level to a lower energy level. The energy is emitted in the form of
radiation. The frequency of the energy emitted is directly proportional to the difference in energy
between the two level.
5) The angular momentum (mvr)of an electron in any orbit is integral multiple of h/2x
mvr = nh/2x
Q4: Name the fundamental particle of an atom write the characteristic of each
particle?
Ans: fundamental particles of atom:- fundamental particle of an atom are:
1)Electron:-
1: It is a negatively charged particle.
2: Its mass is equal to 9.11*10 power-31 kg
3: The charge on electron is unit negatively or 1.6022*10power -19 coulomb
4: Electron are present around the nucleus of an atom.
2) Proton:
1: It is a positively charged particle.
3: The charge on proton is equal to that of electron.
4: Proton are present in the nucleus of an atom.
3) Neutron:
1: Neutron has no charge.
3: It is 1842 times heavier than an electron.
4: Neutron are also present in the nucleus of an atom.

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CHAPTER 7 CHEMICAL BONDING
Q1:Explain ionic bond and covalent bound with any one example?
Ans: Ionic bond:- It is a bond formed by the complete transfer of electrons from one atom to
the other atom. The atom which lose electron acquire positive charge and the one which again
which acquire negative charge. Example is given below;
Consider the formation of NaCl:- In formation of NaCl molecules one electron is
transferred from Na atom to Cl atom their by the octet of each atom is completed.
Covalent bond :-It is the bond formed by the mutual sharing of electron between the two
bonded atoms. Example is given below;
Formation of molecule:-Considered two hydrogen atoms. Each has one electron in its outer
most shell. thus the two atoms contribute there two electron to form a shared pair electron. the
pair of shared electron is known as covalent bond. it is donated by H-H.
Q2:Describe the types of covalent bond?
Ans: Types of covalent bonds
Single covalent bond:-A covalent bond formed by the mutual sharing of one electron pair is
called a covalent and is denoted by single short straight line. For Example in H-Cl, H-H etc.
Double covalent bond:-A covalent bond formed by sharing of two electron pair is denoted
by two short line. For Example in O2, C2 etc
Triple covalent bond:-A three electron pair bond is called a triple covalent bond and is
donated by three short line. In nitrogen there is a triple covalent bond.
Q3:Differentiate between ionic and covalent bond?
Ans: Ionic bond Covalent bond
1: It is formed by the complete transfer of
electron.
1: It is formed by the mutual sharing of electron.
2: In this bond one atom acquire negative
charge.
2: No charges are developed on the two bonded
atoms.
3: Ionic bond are strong. 3: Covalent bond are weak.
Q4:Differentiate between ionic and covalent compound?
Ans: Ionic compound Covalent compound
1: Ionic compound do not contain molecules. 1: Covalent compound contain molecules.
2: Ionic compound are mostly inorganic
compound.
2: Covalent compound are mostly organic
compound.
3: They are usually soluble in water. 3:They are usually insoluble in water.
4: They can conduct electricity. 4: They cannot conduct electricity.
5: They are non volatile in nature. 5: They are volatile in nature.

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Q5:What is chemical bond ?
Ans: Chemical bond: The attractive force which bonds atoms together is called chemical
bond.
Formation of chemical bond: When element react to from a compound, the chemical bond
are formed between atom. all chemical bond between atoms are formed by utilizing the electron
of outer most shell generally the atoms combine with are another in their way.
1) By using electron.
2)By gaining the electron.
3)By sharing the electron.
When the compound undergoes chemical reaction the bond b/w the atoms are rearranged.

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CHAPTER 8 HYDROGEN AND THE ACTIVE METAL
Q1:How Hydrogen is prepared commercially and give its properties?
Ans: Commercial hydrogen is relatively less pure and can be prepared by following methods.
1) Passing steam over red hot coke:- by passing steam over red hot coke we get.
C+H2O CO+H2
carbon monoxide can be separate from the gaseous mixture by liquefying at a temperature of -
200c.
2) By the electrolysis of water:- the purest but expensive hydrogen is obtained by the
electrolysis of water in the presence of little acid.
2H2O 2H2+O2
3) By thermal decomposition:-hydrogen is prepared by thermal decomposition of natural
gas.
CH4 C+2H2
4) pure and relatively in expensive hydrogen is prepared by passing steam aver red hot ion.
3Fe+4H2O Fe3O4+4H2
5) by heating a mixture of natural gas steam the presence of a suitable catalyst nickel.
CH4+H2O 3H2+CO
Properties of hydrogen:
a) Physical properties:-
1) hydrogen has got three isotopic forms known as protium ,deutrium and tritium.
2) at room temperature hydrogen is a colourless, tastelessand odourless gas.
3) molecular hydrogen is the lightest of all gases.
b) Chemical properties:-
1) Reducing agent: Hydrogen is a very reducing agent it can reduce metallic oxides to metal
easily, Example;
CuO+H2 Cu+H2O
2)Reaction with non metal: Hydrogen react with non-metal like oxygen and nitrogen on
heating.
2H2+O2 2H2O
3) Reaction with Helogen: Hydrogen immediately react with halogen to give halides.
H2+Cl2 2HCl
Q2: How Aluminium is extracted from its ore. Give its physical and chemical
properties?
Ans: Preparation:- it is prepared industrially by a proceed called the hall beroult process.
purification of ore:- naturally occurring bauxite contain impurities like silica and oxides of iron.
the first step is obtained aluminium therefore involves the purification of the mineral. the natural

16
bauxite is reacted with a hot concentrated solution of sodium hydroxide and form soluble sodium
alminate .The impurities remain undissolved and ore removed by filtration. aluminium hydroxide
is then precipitate from the solution and is heated to regenerate pure aluminium oxide.
Electrolysis of aluminium:- the pure aluminium oxide obtained by the above process is
dissolved in a molten mixture of cryolite and calcium flouride at 950c. this molten mixture is
electrolysed in a specially designed cell with carbon anode. the final result can be represented by
the following simplified electrode reaction.
Al2O3 2Al+3O
Aluminium is liberated at the cathode and oxygen is liberated at the anode however the atomic
oxygen released at the carbon anode reacts with anode itself to produce carbon dioxide gas.
thus the carbon anodes constantly consumed during the process and they must be replaced at
suitable intervals.
Properties Of Aluminium:-
Physical Properties :-
1)Aluminium has a silvery white lustrous shine.
2)it is a good reflector of heat and light.
3)it is a good conductor of heat and electricity.
4)it has a melting point 66C
Chemical Properties :-
1-Action Of Air :-Dry Has No Action .but in most air when aluminium powder is strongly
heated it forms Aluminium oxide.
2-Action Of Water :-cold water has no effect on pure aluminium. but aluminium powder
decompose water at 100C liberating and forms.
3-Reaction With Alkalis :-Aluminium react vigorously with strong alkalis eg to form
aluminates along with hydrogen .
Q3:What are isotopes? Describe the isotopes of hydrogen?
Ans: Isotopes are atom of same element with same atomic number but different mass number.
isotopes of hydrogen: there are three isotopes of hydrogen i.e.
1)Protium or ordinary hydrogen
2)Deutrium
3)Tritium
1) Protium(ordinary hydrogen):- it most frequently occur in nature. it is represented by
1H1. it has one electron in the nucleus and one electron in the k shell. it occur to 99.98%.
2) Deutrium(heavy hydrogen):- it occur to very little extent. ordinary hydrogen contain
about 1 part of Deutrium in 7000 part of it. it is represented by 1H2 or D. it has one electron and
one neutron in the nucleus and one electron revolves in the K shell.it is usually present in the
form of D2O (heavy water) in ordinary water is small amount.
3) Tritium:- it is the heaviest isotopes of hydrogen and very variously occur in nature. it is
represented by 1H3 or T . it has one proton and two neutron in the nucleus and one electron
revolve in the k shell. it has radioactive form of hydrogen.

17
Q4: How is sodium hydroxide manufactured electrolytically. Give its important
application.
Ans: sodium hydroxide commonly known as caustic soda is commonly manufactured by the
electrolysis of solution sodium chloride which is commonly known as brine.
in this electrolytic process nelson cell is used. in this cell anode consist of graphite rod and a u
shaped perforated steel cathode used. Brine is added in the u tube which on electrolysis gives
chloride anode and sodium at cathode sodium react with water to form sodium hydroxide(caustic
soda).
Application of sodium hydroxide:
1)it is an important laboratory reagent.
2)it is used in paper industry.
3)it is used in the refining of petroleum and oils.

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CHAPTER 9 IRON, COPPER, ZINC AND LEAD
Q1:How is iron manufacture by blast furnace?
Ans: Extraction of iron: iron metal is gradually extracted from its oxide ores by reducing
them with carbon in the form of coal and coke.
the charge, consisting of roasted ores, coke and limestone is fed into the top of the furnace. a
preheated blast of air at about 1500c is blown into the furnace under pressure near to the bottom.
The blast oxidizes the coke to carbon dioxide.
the reaction is highly exothermic considerable heat is librated which raises the temperature about
1900c in this region as the carbon dioxide passes upwards it react with more coke to form carbon
monoxide.
the formation of carbon monoxide is an endothermic process and the temperature in this region
falls to about 1100c .the carbon monoxide thus produced serves as the main reducing agent in the
upper region of the furnace.
the liquid iron runs downward to the bottom of the furnace and is withdrawn through a tap hole.
the lime stone which was added to the charged is known as flux.it decomposes to form CaO and
carbon dioxide. CaO react with the gangue(mostly silica and some aluminia)to form their
respective salts. They are known as slag.
the slag floats as the molten iron and is run off which molten iron is seen into sand moulds where
it cools down to solid blocks called pig iron.
Q2: What is rusting?
Ans: Rusting of iron:- when an iron is exposed to air and moisture its surface is gradually
corroded and converted into a brown mass. this brown mass is known as rust.
Q3: how is rusting conrolled by the cathodic protection and electroplating?
Ans: cathodic protection:-to protect their on object from corrosion by this method the object
is connected to a block of metal such as gine or aluminium which is comparitvely more reaction
than iron when corrsion starts an electrochemical reaction takes place and only the more reaction
prevented from rusting.
Electroplating:-electroplating is used to cover iron object chromium,nickel or other less easily
corroded metals.this process used to prevent decorative as well as protective coatings.
Alloying:-rusting is often prevented by converting the iron into an alloy such as stainless steel.
Painting:- paint is generally used for coating large object such as ship,bridges and soon.
Grease and oil:- grease and oil is used for coating the moving parts of machinery.
Q4: How copper is extracted?
Ans: Extraction of copper:- the extraction of copper from its ore involved concentration
roasting,melting,reducing and electrical refining.
1) Concentration:-the ore is concentrated by a process known as froth floation.in froth
floation the mixture of the mineral and impurities are mixed with water and oil. Pure oil or

19
creosote oil are usually used. air is blown into the mixture and the oil forms a froth which floats
to the surface.the ore particles tend to get coated with oil and are carried to the surface with it.the
froth along with the mineral particles is skimmen off from the top to get the concentrated.
2) Roasting:- the concentrated ore is roasted in a furnace. Part of the sulphur is converted to
sulphur dioxide and other impurities such as arsenic which are burnt off.
3) Smelting:-in the smelting process the roasted ore is mixed with sand and heated strongly
until it melts. The remaining impurities react with the silica to form a slag of molten silicates.
This is removed from the top of the molten mass which remain is called matte and consist of
mixture of CuS2 and FeS.
4) Reduction:-reduction of the matte is carried out in a converter where air is blown through.
The molten material and molten material and molten copper is obtained. more sand is added as a
flux to remove the iron in the form of an iron silicate slag.
5) Refining:- blistered copper is refined by electrolysis. blistered copper, in the anode and a
plate of pure copper is made cathode. a solution of copper sulphate act as the electrolyte. The
impure copper dissolves at the anode and is disposited in the form of pure copper at the cathode.
Q5: Write 3 chemical properties of copper?
Ans: Chemical properties:-
1) copper react with oxygen, sulphur and halogens under suitable condition to from the
corresponding compound.
2) it react with acid which contain oxygen,such as dilute nitric acid and concerned sulphuric
acid.
3) copper displace less reaction metal,such as silver andother precious metals like give and iron.

20
CHAPTER 10 CARBON,SILICON AND NITROGEN
Q1: what is allotropy? describe chief allotropic form of carbon.
Ans: Allotrophy:- various form of the same element which have same chemical properties but
different physical properties are called allotropic forma or allotropes and the phenomenon is
called allotropy.
Allotropic forms of carbon:-
1) diamond
2) graphite
1)Diamond:-diamond is a transparent and bright.it is the hardest of all naturally occurring
substances. It is used commercially for cutting glass, drilling rocks and ornamental purposes. It is
a non-conductor of heat and electricity.
2)Graphite:- it is greyish black and very soft.it is used in making lead pencils. graphite is a
good conductor of electricity.it is not affected by acids or alkalies. It is used as electrodes in
many electrolytic processes.
Q2: Describe the laboratory and industrial preparation of carbon dioxide. What
is the action of carbon dioxide on:
1)magnesium (2) carbon (3) lime water.
Ans: laboratory preparation of carbon dioxide:- it is prepared in the laboratory by the
action of dilute acid on metal carbonates or bicarbonates.
CaCO3+2HCl CaCl2+CO2+H2O
industrial preparation of carbon dioxide:- carbon dioxide is obtained on commercial
scale by heating lime stone in a furnace.
CaCO3 CaO+CO2
carbon dioxide is also obtained as a by product during the production of alcohol from molasses
by fermentation in the presence of yeast.
C6H12O6 2CO2+2C2H5OH
1) Action on megnesium:- highly reactive metals like magnesium continue to burn in
presence of carbon dioxide forming MgO.
2Mg+CO2 2MgO+C
2) Action on carbon:-carbon dioxide is reduced to carbon monoxide when heated in presence
of carbon which have sufficent chemical affinity for oxygen.
C+CO2 2CO
3) Action on lime water:- when carbon dioxide is passed through lime water it is turned
milky due to the formation of calcium carbonate.
Ca(OH)2+CO2 CaCO3+H2O
Q3: What is glass? how is it manufactured? discuss types of glass with their
usefulness?

21
Ans: Glass:-glass is an inorganic super cooled liquid having no definite melting point and has
high viscosity to present. Its crystallization. Glasses are formed by allowing molten silicate to
cool.
Types of glass:
1) ordinary window glass or soda glass:- it prepared by heating a mixture of silica sodium
carbonates and calcium carbonate in a furnace.
CaCO3+SiO2 CaSiO3+CO2
Uses:- it is used in making bottles, windows and all kinds flat glass.
2)borosilicate glass:- borosilicate glass is prepared from silica boronoxide,
aluminuimoxide,and sodiumoxide. This glass is commonly known as Pyrex.
Uses:-it is used for some kitchen and laboratory wares such as ovenware beakers, flask and test
tube.
3) crystal glass:-crystal glass is made from silica lead oxide, potassium carbonate and calcium
carbonate.
Uses:- it is heavy glass which can be cut to give decorative glass ware.
4) Coloured glass:- glass can be prepared in different colors by the addition of small
quantities of contain metallic oxide or salt to molten glass.
5) Water glass and silica gel:- sodium silicate is known as water glass. It is prepared by
heating a mixture of silica and sodium carbonate.
Na2CO3+SiO2 Na2SiO3+CO2
Uses:- water glass is used for various fire proofing materials.
Soda glass:-when an acid is added to a solution of water glass it turns into a jelly like state
known by chemist as a gel. On dehydrating this gel by heating a hard porous material is formed.
this is called silica gel and it is used to absorb gases and vapor.
6) fibre glass:-glass fibre is produced by dropping molten glass into a rotating refectory disc.
the glass files off the disc forming fibre.glass fibre are mixed with plastic are used to mould car
and boat bodies water tanks and sports good.
Q4: how can nitrogen be prepared in the laboratory? what is the action of N2
on:-
1)CaC2 (2) H2 (3) Ca
Ans: Laboratory preparation:- pure nitrogen is obtained in the laboratory by the following
method.
1) by heating a mixture of sodium nitrite and aqueous solution of ammonium chloride.
NH4Cl+NaNO3 NaCl+NH4NO2
NH4NO2 N2+2H2O

22
2) by heating ammonium dichromate.
(NH4)2Cr2O7 Cr2O3+4H2O+N2
3) by the fractional distillation of air.
nitrogen can be obtained by the fractional distillation of liquid air. air from which carbon dioxide
has been removed is liquefied by successive compression and expansion at low temperature.
upon distillation nitrogen gas is evolved first at-196c and thus separated from oxygen.
1)Action on CaC2:- calcium cyanamide is obtained by passing nitrogen over red hot calcium
carbide.
CaC2+N2 CaCN2+C
2) Action on H2:-if a mixture of hydrogen and nitrogen is heated at 400-450c in the presence
of iron oxide and aluminuim sulphate under 200 atmospheric pressure it is converted to
ammonia.
N2+3H2 2NH3
3) Action on calcuim:-calcium is converted to calcium nitrides when heated in a current of
nitrogen.
3Ca+N2 Ca3N2
Q5: Describe Haber process for the manufacture of ammonia.
Ans: this is the most important synthetic method for a large scale preparation of ammonia. a
mixture of pure nitrogen and hydrogen in the proportion of 1:3 by volume is compressed to 200
atmospheric pressure and then passed over iron oxide and alumminuim sulphate as catalyst(iron
containing a little molybdenum) at 400-450c million of tons of ammonia are prepared annually
by this method.
N2+3H2 2NH3
Q6: how is nitric acid manufactured from ammonia by outward method? What
is the action of HNO3 on:
1) CuO (2) Cu (3) Mg
Ans) nitric acid is obtained on a large scale by the oxidation of ammonia. If a mixture of
ammonia and air is heated up to 600c in the presence of platinum nitric oxide if produced.
4NH3+5O2 4NO+6H2O
this an exothermic process and large amount of heat is evolved for this reason the chemical
process continue and nitric oxide is converted to nitrogen peroxide in the presence of excess air.
nitrogen peroxide formed above react with water to from nitric acid.
3NO2+2H2O 2NHO3+NO
1) Action on CuO:- when copper oxide is reacted with nitric acid it produced copper nitrate
and water.
CuO+2NHO3 Cu(NO3)2+H2O
2)Action on copper: when copper is reacted with dilute nitric acid it produced copper nitrate
,nitric acid and water.

23
3Cu+8HNO3 3Cu(NO3)2+4H2O+2NO
3) Action on Mg: when Mg react with nitric acid it produced magnesium nitrate and hydrogen
gas is evolved.
Mg+2HNO3 Mg(NO)3+H2

24
CHAPTER 11 OXYGEN,SULPHUR AND CHLORINE
Q1: How is oxygen industrially prepared from air and water?
Ans: Industrial preparation: oxygen is obtained on an industrial scale from air and water.
1) from air:-
(a) air is a mixture of oxygen and nitrogen the ratio by volume being 21:78. the air is liquefied by
cooling under pressure and the liquid ait fractionally distilled. Nitrogen being more
volatile(boiling point-196c) escapes out first and oxygen being less volatile (boiling point -183)
is left behind.
(b) oxygen can also be obtained from air by a chemical method. barium oxide is heated upto
500c in air which combine with the oxygen of air and is converted into barium peroxide. barium
peroxide on heating at 1000c decompose into oxygen and barium oxide.
2BaO+O2 2BaO2
2) from water:-oxygen is obtained on large scale by electrolysis of water.
2H2O 2H2+O2
Q2: what is action of O2 on:-
1) C (2) Ca (3) Al
Ans: Reaction with non metal:- nonmetal such as carbon, sulphur, phosphorus burn in
oxygen forming their respective oxides. Hydrogen burns violently with oxygen to form water.
C+O2 CO2
2) Reaction with metal:-highly reactive metals such as sodium and potassium react rapidly
with oxygen at low temperature.
2Na+O2 2Na2O
3)Reaction with aluminium:- aluminuim powder burns violently in oxygen. Flash bulbs
used in photography contain aluminium foil in an atmosphere of oxygen.
2Al+3O2 2Al2O3
Q3: What are oxides? Discuss various type of oxide give their characteristic
properties.
Ans: Oxides:-the binary compounds of the element with oxygen are called oxides.
on the basic of valence number of oxygen they are ordinarily classified into four main groups,
namely:-
1) normal oxide
2) peroxide
3) super oxide
4) suboxide
1)Normal oxides:- there are the oxides in which the valence number of oxygen is -2.
normal oxide are classified into four types.

25
a) Aasic oxide:- these oxide react with acid to produced salt and water.
b) Acidic oxide:- these oxide react with base to from salt and water.
c) Nuetral oxide:- these oxide are neither acid or a base their have no action on blue or red
litmus.
d) Amphoteric oxide:-these are oxide which possess the properties of an acid as well as a
base.
2) Peroxide:-the valence number of oxygen in peroxide is -1.peroxide form hydrogen peroxide
on reaction with dilute acid. Example of peroxide are sodium peroxide, barium peroxide and
hydrogen peroxide.
3) Superoxides:- the valence number of oxygen in super oxide in -1/2. superoxide have an
excess amount of oxygen than normal and superoxides.
4) Suboxide:- suboxide have less quantity of oxygen than the normal oxides, they are unstable
and very few suboxide are known. an example of suboxide is C3O2 which is named as carbon
suboxide.
Q4: How is ozone produced? discuss the usefulness of protective layer of ozone
and its deplation
Ans: Ozone:-ozone,wich has a molecular formula O3, is an allotropic from of oxygen when an
electrical discharge passes through ordinary diatomic oxygen energy is absorbed and some of
oxygen is converted to ozone.
3O2 2O3
due to the presence of this extra oxygen ozone is used for disinfecting water supplies and large
summing pools the atomic oxygen kills any harmful bacteria present because of this property
ozone is used to sterilize air in confined and crowded spaces such as underground railway
stations and slaughter houses.
ozone also find applications as a bleaching agent for oils waxes starch and flour. the atomic
oxygen it releases, bleaches the organic dyes present in these material by oxidizing them.
Q5: How is sulphur extracted by frasch process.
Ans: Extraction of sulphur:- harmen frasch developed a method for extraction of sulphur.
the basic principle of this method is that sulphur is method under ground and pumped up to the
surface. the details of the method are describe below.
a bore is made to the deposits of sulphur and three concentric pipes are sunk into the bore. the
outermost pipe (20 cm diameter) is sunk up to the deposits and the most inner (10 cm diameter)
is held a little above the surface of deposits. Super-heated water at 170c under a pressure of 16
atom is pumped down the outermost pipe. This water melts the sulphur (m.p 113c) which collect
in a pool at the bottom. hot compressed air is blown down the innermostpipe.it forms a foam of
molten sulphur which arises through the amnular space between the inner most pipe and the next
when this foam of sulphur reaches the surface it is collected in big wooden basin. after
sometimes air escapes and sulphur solidifies in huge blocks at the bottom of tanks. Sulphur
obtained by this process is 99.5 percent pure.

26
Q6: How is Sulphur dioxide prepared in laboratory?
Ans: Laboratory preparation:- sulphur dioxide is prepared by heating copper turning with
concentrated sulphuric acid in round bottomed flask fitted with delivery tube and the gas is
collected by upward displacement of air.
Cu+2H2SO4 CuSO4+2H2O+SO2
Q7: What is the reaction of Sulphur dioxide on:-
H2O, H2S,FeCl3
Ans: reaction with water:- when sulphur dioxide is dissolved in water it froms sulphurous
acid which decompose into its constituent on heating.
SO2+H2O H2SO3
Oxidizing nature:- sulphur dioxide behaves as an oxidizing agent towards hydrogen sulphide
and carbon monoxide.
2H2S+SO2 2H2O+3S
Reducing nature:-because of its tendency to remove oxygen in the presence of water sulphur
dioxide acts as a strong reducing agent.
2FeCl3+SO2+H2O H2SO4+2FeCl2+2H2
Q8: How is Sulphuric acid manufactured?
Ans: contact process:- now a day sulphuric acid is mostly manufactured by contact process.
sulphur or iron pyrite is burnt in a regular supply of air to produce sulphur dioxide.
S+O2 SO2
4FeS2+11O2 2Fe2O3+8SO4
the resulting sulphur dioxide along with excess of air is purified from dust particles and
arsenious oxide by passing gases through a dust chember in to whch steam is injected.the solid
particles of impurities form droplet of water with steam and settle down.the moist gases are then
dried by passing through a drying tower on which concentrated sulphuric acid is
sprayed.arsenious oxide is then removed by passing the gases through a chamber provider with
shelves packed with freshly prepared ferric chloride.
after the removal of dust and other impurities the gases are passed through a contact chamber
packed with plantinished asbestos or vomaduim pentoxide. the chamber is heated upto 450c
where sulphur dioxide and air combine to form sulphur trioxide.
2SO2+O2 2SO3
sulphur trioxide thus obtained is absorbed in 97 percent sulphuric acid flovuing down a tower.
The oleum or pyrosulphuric acid thus produced is diluted in tanks with a calculated amount of
water in order to get 100 percent pure sulphuric acid.
SO3+H2SO4 H2S2O2
H2S2O2+H2O 2H2SO4

27
Q9: Give laboratory and industrial preparation of chlorine?
Ans: Laboratory preparation:- chlorine is usually prepared in the laboratory by the
oxidation of hydrochloric acid. concentrated hydrochloric acid and manganese dioxide are heated
slowly in a round bottom flask.
on heating greenish yellow chlorine gas comes out which is collected by the upward
displacement of air.it is poisonous gas and hence on efficient ventilation of the laboratory is
necessary.
MnO2+4HCl MnCl2+2H2O+Cl2
Industrial preparation:- the chlorine gas is obtained on a large scale by the electrolysis of an
aqueous solution of sodium chloride. chlorine is collected at the anode and sodium hydroxide is
produced in the cell around the cathode.
NaCl+H2O Cl2+H2+2NaOH
Q10: What is the action of chlorine on:-
1) CH4 (2) CO (3) NH3
Ans: Reaction with hydrocarbons:- chlorine reacts with hydrocarbons in chain reaction to
giveCCl4 and HCl
CH4+4Cl2 CCl4+4HCl
Reaction with carbon monoxide :- chlorine react with carbon monoxide to give phosgene.
CO+Cl2 COCl2
Reaction with nonmetal:-nonmetal like iron and tin combine with chlorine on heating.
Sn+2Cl2 SnCl4

28
CHAPTER 12 AN INTRODUCTION OF ORGANIC CHEMISTRY
Q1: Difference between organic compound and inorganic compound.
Ans: Organic compound Inorganic compound
1) carbon is essential constituent of organic
compound.
1) presence of carbon is not essential but it is present in
carbonates, bicarbonates and Cyanamid’s.
2) carbon and hydrogen are involved in their
preparation.
2) carbon and hydrogen may not even be present.
3) usually they decompose at high
temperature in the simple compound.
3) usually they are stable at high temperature.
4) most organic compound readily catch fire. 4) most inorganic compound do not catch fire.
5) their melting and boiling point are low. 5) their melting and boiling point are usually high.
6) organic compound contain covalent bond
.
6) ionic bond are frequently in inorganic compound.
7) their molecular mass is very high. 7) molecular mass are usually low.
8) these are usually soluble in organic
solvent.
8) these are insoluble in inorganic solvent.
Q2: write the structure of methane and its chemical properties?
Ans: Methane structure:- the carbon atom has four electron in tis valence shell. in molecule
of methane it shares these with four hydrogen atom forming four covalent bond.
each of the four covalent bond consist of a shared pairs of electron obviously these shared pair of
electron are negatively charged so they tend to repel catch other and move as far as possible the
maximum separation of the bond is achieved in a regular tetrahedral structure with the carbon
atom at the center and four hydrogen atom at the apiece the angle between any two C-H bond is
the same about 109.5c.
Chemical properties
Combustion:- methane is an important fuel and its most important chemical property is that it burns in air on
oxygen with a non-luminous flame. the burning of methane in air or oxygen is an exothermic reaction during which
carbondioxide water and heat energy are produced.
Reaction with helogens:- methane react with chlorine in presence of sunlight in such a way that the four
hydrogen atom of methane are replaced one by one in a step wise manner.
Q3: Write the process of fractional distillation of petroleum?
Ans: various fraction are separated according to the difference in their boiling points and put to
various uses. this method is known as fractional distillation and comprise as evaporation and
condensation.
the petroleum to be refined is first heated in a special furnace called pipe still about 371-426c.

29
the presence in the pipe is so adjusted as to avoid evaporation of the crude oil. the hot petroleum
from the pipe still then goes to bottom of a fractionating tower. here the pressure is released and
the liquid vaporizes. the vapor go up the fractionating tower where hydrocarbon that have high
boiling temperature range are easily condensed to liquid in the lower part of the tower the
fraction like gasoline which lower boiling temperature range continue to move up the tower as
vapors which are them led to condenser where they change to liquid state.
Q4: write difference between drugs and medicine and write important drugs and
their abuses?
Ans: Definition of drugs:- a drugs is defined as a substance which affect most of the
physiological function of a man or an animal.
definetion of medicine:- a medicine is defined as any drugs prescribed by a physician for the
treatment of an ailment of a patient. Important drugs and their abuses:- drugs (intoxicants) can be
put into four groups.
1) Sleeming drugs:- the drugs like alcohol, barbitroat and tranquilizes are included in this
group their continue use damages the will power and memory of a person continuous use of
alcohol can permanently damage the heart, liver and brain.
2) Stimulants:- drugs like cocaine, nicotine, caffeine, amphetamine are included in this group.
due to the use of such drugs the energy of the body begins to be used up rapidly their use
increases the normal heart beat and blood pressure.
3) Narcotics:- drugs like heroin codine and opium are included in this group the common
action in these drugs on the nervous system is that it make it quite dull and brain control of
bodies organs is lost. feeling of hunger is lost and one suffer from constipation.
4) Hallucinogens:- this includes charas, bhang and marijuana. in this case, the effect is so
dangerous that the addict loses his balance of mind his nerves get so much weak that his loses all
his thinking and the capacity of understanding.

Chemistry Notes for Class Ninth (by: Seetal Daas)

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Chemistry Notes for Class Ninth (by: Seetal Daas)