Carbon & Its Compounds CLASS X

YOUR LOGO
CLASS - X (CHEMISTRY)
CARBON AND ITS COMPOUNDS
99 92
0523
r i ter 79
ent W
Cont
Name: _________ Roll no. __
THIS MATERIAL AVAILABLE WITH YOUR NAME AND LOGO CONTACT ME 7905239992
Chapter
CARBON &
ITS COMPOUNDS

Chapter Outline

 Bonding in Carbon: The Covalent Bond

 Allotropes of Carbon
 Versatile nature of Carbon Diamond
 Organic Compounds
 Classification of Organic Compounds
 Hydrocarbons and Functional Groups
 Homologous Series
 Nomenclature of Organic Compounds
 Isomerism
 Chemical Reaction of
Carbon Compounds
 Some Important Organic Compounds
 Ethanol
 Ethanoic Acid Graphite
 Soaps & Detergents
Fullerene
01
MIND MAP
CARBON
Bonding in Carbon Allotropes of Isomerism in Important Carbon

& its Compound Carbon Carbon Compounds Compound
(Covalent Bonding)
Nomenclature of
Carbon Compounds
Ethanol Ethanoic
acid
Crystalline Non-Crystalline
Nature or Amorphous Chain Position Functional
Nature
Coal
Diamond Fullerene
Charcoal
Chemical Reactions of Carbon Compound
Graphite Lamp black
Combustion
Oxidation
Addition
Substitution
2 | Carbon and Its Compounds ________________________________________________CAREER POINT

02
CARBON AND ITS COMOPUNDS
Introduction
Carbon is a very important non-metal. The name carbon is derived from the Latin word 'carbon' which
means 'coal'. This is because it is the main constituent of coal. Carbon is the major chemical of most
organic matter from fossil fuels to complex molecules (DNA and RNA) that control genetic reproduction
in organisms. The earth's crust has only 0.02 % carbon in the form of minerals (like carbonates,
hydrogen carbonates, coal and petroleum) and the atmosphere has 0.04 % carbon dioxide. Inspite of
this small amount of carbon available in nature, the importance of carbon seems to be immense
because carbon forms innumerable compounds by combining with other elements.
Bonding in Carbon-The Covalent Bond

Let us now study the properties of some carbon compounds. Melting and boiling points of some carbon
compounds are given in Table.
Compound Melting Point (K) Boiling Point (K)
Acetic acid (CH3COOH) 290 391
Chloroform (CHCl3) 209 334
Ethanol (CH3CH2OH) 156 351
Methane (CH4) 90 111
From the above data it is clear that the boiling and melting points of carbon compounds are very low.
This is due to the reason that the forces of attraction between the molecules of these compounds are not
strong. Since these compounds are largely non-conductors of electricity, we can conclude that the
bonding in these compounds does not give rise to any ions.
The atomic number of carbon is 6. So, its electronic configuration is:
K L
6C 2 4 (1s2, 2s2 2p2)
The configuration shows that carbon is an element of 2nd period and 14th group, in the p-block.
Note : 14th group in the periodic table is called the carbon family. Other members of this group are Si, Ge, Sn, Pb.
 Formation of Covalent Bond

We know that the reactivity of elements is explained as their tendency to attain a completely filled
outer shell, i.e., attain noble gas configuration. Elements forming ionic compounds achieve this by
either gaining or losing electrons from the outermost shell. In case of carbon, it has four electrons in its
outermost shell and need to gain or lose four electrons to attain noble gas configuration. If it were to
gain or lose electrons:
(i) It could gain four electrons forming C4– anion but it would be difficult for the nucleus with six
protons to hold on to ten electrons, i.e., four extra electrons.
(ii) It could lose four electrons forming C4+ cation but it would require a large amount of energy to
remove four electrons leaving behind a carbon cation with six protons in its nucleus holding on the
just two electrons.
Thus, carbon can neither gain nor lose 4 electrons to acquire the nearest noble gas configuration. The
only way by which it can acquire the nearest noble gas configuration is by sharing of its valence
electrons with electrons of other carbon atoms or atoms of other element. Not just carbon, many other
elements also form molecules by sharing of valence electrons.
CAREER POINT _______________________________________________ Carbon and Its Compounds | 3
03
 Concept of Covalent Bond
Formation of covalent bond involves the sharing of electrons between the bonding atoms which may be
either same or different. Each atom contributes equal number of electrons for sharing. These shared
electrons form common pairs or shared pairs which belong to the outermost shells of both the
combining atoms. As a result, both the combining atoms acquire the stable configuration of the nearest
noble gas. Such bonds which are formed by mutual sharing of electrons between two atoms are called
covalent bonds. Thus, a chemical bond formed between two atoms by mutual sharing of valence
electrons between two atoms so that each atom acquires the stable electronic configuration of the
nearest noble gas is called a covalent bond and the compounds formed by sharing of electrons are called
covalent compounds.
 Examples of formation of Covalent Bonds
1. Formation of hydrogen (H2) molecules: The atomic number of hydrogen is 1. Hence, hydrogen
has one electron in its K-shell and thus requires one more electron to complete the K-shell,. So, two
hydrogen atoms share one electron each to form a molecule of hydrogen, H2. By doing so, each
hydrogen atom attains the stable electronic configuration of the nearest noble gas, helium, which
has two electrons in its K-shell. We can depict the formation of diatomic molecule of H2 using dots
or crosses to represent the valence electrons involved in sharing. Such structures of molecules are
called electron dot structures. The electrons dot structure of H2 molecule is shown in figure.
Shared electrons
or
Shared pair
H + H H H or H–H
Hydrogen atomHydrogen atom Hydrogen molecule

Electron dot structure of Hydrogen (H2)
molecule
The shared pair is said to constitute a single covalent bond between two hydrogen atoms and is
represented by a single line between the two hydrogen atoms.
Shared pairs are also called bond pairs since they bind the combining atoms together.
2. Formation of nitrogen (N2) molecule: The atomic number of nitrogen is 7. So, its electronic
configuration is:
7N = K L (1s2, 2s2 2p3)
2 5
Thus, nitrogen has 5 electrons in the L-shell (i.e., valence shell). Therefore, it needs three more
electrons to complete its octet. By doing so, each nitrogen shares three electrons with another atom
of nitrogen to form a diatomic molecule of nitrogen. By doing so, each nitrogen atom acquires the
stable electronic configuration of the nearest noble gas, neon. The three electrons contributed by
each nitrogen atom give rise to three shared pair of electrons. These three shared pairs of electrons
constitute a triple bond between the two nitrogen atoms which is represented by a triple line. One
pair of electrons on each nitrogen atom in N2 molecule which is not involved in bond formation is
called the lone pair. The electron dot structure of a diatomic molecule of nitrogen is shown in
figure.
Three shared pairs
N + N N N or N = N
Nitrogen atomNitrogen atom Nitrogen molecule

Electron dot structure of nitrogen (N2) molecule

04
3. Formation of methane (CH4) molecule: Methane is the simplest carbon compound. Its formula
is CH4. It is widely used as a fuel and is the major component of Bio-gas Compressed Natural Gas
(CNG). The atomic number of carbon is 6 and its electronic configuration is:
6C = K L
2 4
Thus, carbon has 4 electrons in the valence shell (i.e., L-shell) and hence, needs four more electrons
to complete its octet by acquiring the stable electronic configuration of the nearest noble gas, neon.
Thus, the valency of carbon is 4. In other words, carbon is tetravalent.
On the other hand, the atomic number of hydrogen is 1. In other words, hydrogen has one electron
in the K-shell (i.e., valence shell) and thus needs one more electron to complete its duplet by
acquiring the stable electronic configuration of the nearest noble gas, helium.
In order to complete its octet, carbon shares its four valence electrons, with one electron each of
four hydrogen atoms to form a molecule of methane. By doing so, each hydrogen atom completes its
duplet. The four shared pairs of electrons form four C–H single covalent bonds. The electron dot
structure of methane molecule is shown in figure.
H Shared pair H
×
C + 4 ×H H× C × H or H–C–
Four H-atoms × H
One C-atom Shared pair H Shared pair
Methane molecule
Electron dot structure of methane (CH4)
molecule
 Homoatomic and Heteroatomic Molecules
Molecules which are made up of only one kind of atoms such as H2, Cl2, O2, N2, etc., are called
homoatomic molecules while those which are made up of more than one type of atoms such as CH4,
NH3, HCl, etc., are called heteroatomic molecules.
COMPETITIVE LEVEL
Covalency: Covalency of an element may be defined as the number of electrons which an atom of an
element shares.
In H2 molecules both the atoms share one electron each hence, have a covalency of one. In O2 molecule
both the atoms share two electrons and hence, have a covalency of two while in nitrogen molecule both
the atom share three electrons and hence, have a covalency of three.
 Properties of Covalent Compounds

1. Physical State: Covalent compounds exist as gases, liquids or solids. For example, NH3, CH4, SO2,
etc, exist as gases, while H2O exist as liquid and C12H22O11, (C2H4)n exist as solids.
2. Melting and boiling points: Since, no ions are present in the covalent molecules, the attractive
forces in them are weak. Therefore, these compounds have usually low melting and boiling points.
3. Electrical conductivity: Covalent compounds do not conduct electricity. This means that covalent
compounds are bad conductor of electricity due to absence of free ions. For example, covalent
compounds like glucose, sugar, urea, alcohol and carbon tetrachloride, etc., do not conduct electricity
because they do not contain ions. Some polar covalent compounds like hydrogen chloride gas,
however, conduct electricity when dissolved in water since it dissociates into H+ (aq) and Cl– (aq)
ions and hence, it becomes a good conductor of electricity.
4. Nature of reactions: Covalent compounds generally undergo molecular reactions.
5. Solubility: Covalent compounds are usually insoluble in water but they are soluble in organic
solvents. For example, naphthalene is insoluble in water but dissolves in organic solvents like ether.
Some of the covalent compounds like glucose, sugar and urea, etc., are however, soluble in water.
The polar covalent compounds like hydrogen chloride and ammonia are also soluble in water.

05
Ex.1 Give differences between ionic and covalent compounds.
Sol. Difference in the properties of ionic and covalent compounds
S.No. Ionic Compounds Covalent Compounds

1. These are formed by the transfer These are formed by mutual
of one or more electrons from one sharing of electrons between the
atom to the other. bonded atoms.
2. These are formed between atoms These are formed between the
of metals and non-metals atoms of non-metals.
3. They are high melting and They have low melting and boiling
boiling points due to strong points because no ions are involved
forces of attraction between in their formation.
oppositely charged ions.
4. They are soluble in polar solvents They are generally insoluble in
like water but are insoluble in polar solvents like water but are
organic solvents like alcohol, soluble in non-polar solvents like
benzen, petrol, ether, chloroform, alcohol, benzene, petrol, ether,
etc. chloroform, etc.
5. They do not conduct electricity in They do not contain ions and hence,
the solid state but do so in the are generally bad conductors, of
molten state or in their aqueous electricity.
solution.
6. They undergo ionic reactions They undergo molecular reactions
which are very fast. which are slow.
Ex.2 What would be the electron dot structure of a molecule of sulphur which is made up of eight atoms
of sulphur?
Sol. The atomic number of sulphur is 16. So, its electronic configuration is
K L M
2 8 6
Thus, sulphur atom has 6 electrons in the valence shell. Therefore, it needs two more electrons to
complete its octer. Each sulphur atom shares two of its valence electrons, one each with the other
two sulphur atoms forming a eight membered ring as shown below:
S S
S S
S S S
S S S S
S S S
S S
a b
Electron dot structure of octagonal Crown shaped S8
S8 molecule molecule

06
Ex.3 Draw the electron dot structure of oxygen molecule.
Sol. The atomic number of oxygen is 8. So, its electronic configuration is:
K L
8O = 2 6 (1s2, 2s2 2p4)
The electron dot structure of oxygen molecule is shown in figure.
Two shared pairs
O + O O O or O = O
Oxygen atom Oxygen atom Oxygen molecule

Electron dot structure of oxygen (O2) molecule
Allotropes of Carbon
Allotropes: When an element is found in different forms having different physical properties but
almost similar chemical properties, the phenomenon is known as allotropy and different forms are
called allotropic forms of that element.
Elements such as carbon, oxygen, phosphorus and sulphur display allotropy.
Carbon exists in both crystalline and amorphous allotropic forms.
 Crystalline Allotropes of Carbon
 The crystalline varieties of carbon are diamond, graphite and fullerene.
1. Diamond:
 Structure of Diamond: Diamond possesses a three dimensional network of carbon atoms
joined together tertrahedrally through strong covalent bonds. Each carbon atom is linked
tetrahedrally to four neighbouring carbon atoms extended in three dimensions such that each
carbon atom lies at the centre of regular tetrahedron with the vertices occupied by other carbon
atoms. All C–C bonds are of equal lengths 154 pm (1.54 Å) with bond angle 109º 28'.
Structure of diamond
 Properties of Diamond:
(i) It is the purest and densest form of carbon having density 3.51 g cm–3. It is insoluble in all
solvents.
(ii) It is the hardest naturally known substance. Due to the presence of very strong covalent
bonds, the network is very hard and diamond is extremely hard with a very high melting
point (3843 K).
(iii) It is a bad conductor of electricity since all the valence electrons of each carbon atom are
involved in the formation of C–C bonds leaving no free and unpaired electron in the
crystal.
07
(iv) Diamond is resistant to almost all acids, alkalis and salts. However, it reacts with fused
sodium carbonate. On strong heating with a mixture of potassium dichromatic and
sulphuric acid to 475 K, it slowly gets oxidized to carbon dioxide.
(v) It is transparent and possesses high refractive index (2.45) and therefore diamond is a
precious stone and used to jewelleries. The market value of a diamond depends upn its
size and colour. Blusih-white diamonds are more precious and costly than those having
yellowish colour. Black diamonds being the cheapest and not used in jewellery.
 Uses of Diamond:
(i) As a precious stone in jewellery.
(ii) Black diamond is used for cutting glass and for making rock drills.
(iii) In preparation of dies used for drawing very thin wires of metals like tungsten.
(iv) Most industrial diamonds are often used as an abrasive because there very hard.
(v) Surgeons used diamond knives for performing delicate operations.
2. Graphite:
 Structure of graphite: Each carbon atom in graphite is covalently attached to three
neighboring carbon atoms lying in the same plane giving rise to planar hexagonal rings. The C–
C bond length in these rings is 142 pm (1.42 Å), and are separated by a distance of 340 pm (3.4
Å). Due to weak Van der Walls' forces, the sheets are not firmly attached and can slide over one
another. This is why graphite is soft and possesses lubricating properties.
Vander waal forces
Structure of graphite
 Properties of Graphite:
(i) It is a dark grey substance with a metallic luster.
(ii) Graphite has density (2.25 g cm–1) due to large separation between the adjacent layers. It
is very soft, opaque and slippery to touch.
(iii) It leaves a black mark on paper and is used in lead pencils.
(iv) It is a good conductor of electricity due to unpaired electron left on each carbon atom.
(v) It is not attacked by dilute acids, alkalis and chlorine. A mixture of potassium dichromatie
and sulphuric acid oxidizes it slowly to carbon dioxide.

08
 Uses of Graphite:
(i) in making electrodes and carbon arcs.
(ii) as a lubricant for machines working at high temperature.
(iii) in the manufacture of lead pencils. The powered graphite is mixed with clay and pressed
into sticks. These sticks are used to make pencils.
(iv) for making shoe polish and paints.
(v) as a moderator in atomic reactors.
Table: Difference in the properties of

diamond and graphite.
S.No. Diamond Graphite
1. Crystalline, transparent with extra brilliance. Crystalline, opaque and shiny substance.
2. Hardest form Soft having soapy touch.
3. Bad conductor of electricity. Good conductor of electricity.
3 3
4. High density (3.51 g/cm ) Low density (2.25 g/cm )
5. Colourless. Greyish white.
6. Tetrahedral structure Two dimensional layer structrure with regular
hexagonal sheets.
7. Less stable, more energy More stable, less energy.
8. Melting point is about 3527ºC Melting point is about 4027ºC
3. Fullerenes:
(i) Fullerene or Buckminster fullerene of molecular formula C60 was discovered by H.W. Kroto,
R.F. Curl and R.E. Smalley in 1985. They are awarded Nobel prize in 1996 for the outstanding
discovery of fullerenes.
(ii) The name Buckminster fullerene was given to C60 in the honour of Robert Buckminster fuller
whose geodesic dome structure incorporated patterns of hexagons with sufficient pentagons to
give clusters. The structure of Buckminster fullerene (C60) is shown in figure. Its shape
resembles to that of a soccer ball (football). Fullerenes containing carbon clusters upto 600
carbon atoms have been observed.
The soccer ball structure of

Buckminster Fullerene (C60)
Note: C60 molecules is made of 20 hexagons and 12 pentagons.
(iii) Fullerene is large spheroidal cage like molecules of carbon having formula C60.
(iv) Naturally fullerenes were discovered at the impact sites of ancient meteorites.
(v) Fullerenes are soluble in organic solvents and form coloured solutions. A solution of C60 in
toluene is purple, whereas that of C70 is orange red.

09
COMPETITIVE LEVEL
 Amorphous Forms of Carbon

Carbon also exists in amorphous forms. Some amorphous forms of carbon are as follows:
1. Coal: Coal deposits found in almost all parts of the world are formed by the slow carbonization of
the vegetable matter deep buried in the layers of earth long-long ago. In coal deposits carbon is in
impure form and exists in several varieties such as peat (60% C), lignite (70% C), bituminous coal
(78% C). semibituminous (83% C) and anthracite (90% C).
Coal is extensively used as fuel in boilers, engines, furnaces and in manufacture of fuel gases and
synthetic petrol.
   Destructive distillation of coal gives four products – coke, coal gas, coal tar and ammonical
liquor. Coke is a grayish black hard solid which contains about 80-95% carbon. It is mainly
used as a fuel and also as a reducing agent in metallurgical process.
2. Charcoal: Charcoal is a light, black residue, consisting of carbon and any remaining ash, obtained
by removing water and other volatile constituents from animal and vegetation substances. It is of
three types –
(i) Wood charcoal: Destructive distillation of wood gives a black, soft and porous solid wood
charcoal. It is capable of adsorbing colouring matter and odoriferous gases. It is used as a fuel
deodorant, decolourising matter and in gun powder.
(ii) Animal charcoal (Bone black): Destructive distillation of animal bones gives animal charcoal
containing about 10 % carbon. It is a better adsorbent than wood charcoal and is mainly used
for decolourising organic substances and raw sugar solutions.
(iii) Sugar Charcoal: The purest form of charcoal. Sugar charcoal is obtained by heating canesugar
in the absence of air.

C12H22O11  12C + 11H2O
Sugar charcoal
3. Lamp black (Soot): Burning carbon rich substances such as tar, turpentine oil, kerosene,
petroleum etc., in limited supply of air gives velvety (soft and smooth) black powder (called lamp
black) containing about 89-99 % carbon. It is commonly used in making printing ink, black paints,
boot polishes and as a filler in the rubber industry.
   Gas Carbon: During destructive distillation of coal some carbon present in smoke is condensed
on the inner walls of retort. The scrapped carbon taken out from the walls of retort called gas
carbon. It is a good conductor of electricity and is used for making electrodes
Versatile Nature of Carbon

Many of the things we use in our day to day life are made up of carbon compounds. In fact, we
ourselves are made up of carbon compounds. The number of carbon compounds known today is
approximately three million. This number far exceeds the total number of compounds formed by all
other elements.
Why is it that this property is seen in carbon and in no other element? The nature of the covalent bond
enables carbon to form a large number of compounds.
The four main characteristic properties of carbon atom which lead to formation of a very large number
of organic compounds are:
10 | Carbon and Its THIS

Compounds _______________________________________________CAREER POINT
MATERIAL AVAILABLE WITH YOUR NAME AND LOGO CONTACT ME 7905239992
10
1. Catenation: The main reason as to why carbon forms a large number of organic compounds is that
carbon can combine with other carbon atoms to form straight or branched chains of varying lengths
or rings of different sizes as shown below:
C C C C C C C
Straight chain C
Branched chain
C C
C
C C C C
Three-membered ring Four-membered ring
C
C
C C
C C
C C
C C C
Five-membered ring Six-membered ring

This unique property of self-linking of carbon atoms through covalent bonds to form long straight
or branched chains and rings of different sizes is called catenation.
No other element exhibits the property of catenation to the extent seen in carbon atoms. Silicon
forms compounds with hydrogen which have chains of upto seven or eight atoms, but these
compounds are very reactive. The carbon-carbon bond is very strong and hence, stable. This gives
us the large number of compounds with many carbon atoms linked to each other.
2. Tetra-valency of carbon: Carbon has a valency of four. Therefore, it is capable of bonding with
four other atoms. The bonds formed by carbon with other atoms are very strong and hence the
molecules are very stable. This further increases the number of carbon compounds.
3. Tendency to form multiple bonds: Due to small size, carbon also forms multiple (double and triple)
bonds with other carbon atoms, oxygen, sulphur and nitrogen. This multiplicity of carbon-carbon,
carbon-oxygen and carbon-nitrogen bonds further increases the number of carbon compounds.
4. Isomerism : Another reason for huge number of carbon compounds is the phenomenon of isomerism.
Isomerism is defined as follows:
If a given molecular formula represents two or more structures having different properties, the
phenomenon is called isomerism and the different structure structures are called isomers. For
example,
Isomers of Butane-C4H10 are:
CH 3
|
1
CH 3  CH 2  CH 2  CH 3 , CH 3  2 CH  3 CH 3
n  Bu tan e Isobu tan e
( Bu tan e ) ( 2  Methypropa ne )
Thus, the number of different structures with the same molecular formula further increases the
number of carbon compounds.
CAREER POINT ______________________________________________ Carbon and Its Compounds | 11

11
Organic Compounds
Two characteristic features of carbon i.e., tetravalency and catenation put together, give rise to a large
number of compounds. Many have the same non-carbon or group of atoms attached to different carbon
chains these compounds were initially extracted from natural substances and it was thought that these
carbon compounds or organic compounds could only be formed within a living system. Thus these
carbon compounds were named organic compounds and were defined as- 'Those compounds of carbon
that are directly or indirectly obtained from organism.'
 Berzelius Hypothesis or Vital Force theory
Organic compounds cannot be synthesized in the laboratory because they require the presence of a
mysterious force (called vital force) which exists only in living organisms.
 Wohler's Synthesis
In 1828, Friedrich Wohler synthesized urea (a well known organic compound) in the laboratory by
heating ammonium cyanate.
(NH 4 ) 2 SO 4 + 2KCNO  2NH 4 CNO + K 2SO 4
Ammonium Potassium Ammonium Potassium
sulphate cyanate cyanate sulphate
O
Heat |
|
NH 4 CNO     NH  C  NH
Re arrangement
Ammonium 2 2
cyanate
Urea
Ex.4 Why carbon shows the property of catenation?

Sol. The property of catenation is probably due to
(i) small size
(ii) unique electronic configuration, and
(iii) great strength of carbon-carbon bonds.
Ex.5 Name the first organic compound synthesized in the laboratory..

Sol. Urea is the first organic compound synthesized in the laboratory.
Modern Definition of Organic Compounds
With the downfall of the Vital force theory, the word organic pertaining to life lost its significance. An
analysis of these compounds revealed that all them contain carbon as their essential constituents.
Therefore, the organic compounds were regarded as the carbon compounds. This definition was little
confusing because according to this, typical inorganic compounds like carbon monoxide, carbon dioxide
and carbonates of certain metals should also be regarded as organic compounds.
However, a detailed investigation of the structure of the organic compounds revealed that almost all of
them essentially contain both carbon and hydrogen (hydrocarbons) and some of them also contain the
atoms of a few other elements such as nitrogen, oxygen, phosphorus, halogens, etc. These are regarded
as the derivatives of hydrocarbons since, they can be formed by replacing the hydrogen atoms in the
hydrocarbons by these atoms.
Thus: Organic compounds are the hydrocarbons and their derivatives and the branch of chemistry that
deals with the study of these compounds in known as organic chemistry.
Note: Oxides of carbon (like carbon monoxide and carbon dioxide), carbonates and hydrogen carbonate
salts are not considered to be organic compounds. This is because their properties are very different
from those of the common organic compounds.

12
Classification of Organic Compounds
The organic compounds can broadly be classified as follows:
Organic (Carbon) Compounds
Open chain or Closed chain (Cyclic)

Acyclic compounds or
Ring Compounds
Saturated Unsaturated
Homocyclic or Carbocylic Heterocyclic

Compounds Compounds
Alicyclic Aromatic Alicyclic Aromatic

Compounds Compounds Compounds Compounds
1. Open chain or Acyclic Compounds: Compounds containing open chains of carbon atoms are
referred to as open chain compounds or acyclic compounds or aliphatic compounds. The carbon
chains may be either straight or branched e.g.:
H
H C H
H H H H H
H H H
H C C C H H C C C H
H C H H C C H
H H H H H H
H H H
(CH3CH2CH3, Propene) (CH3–CH –CH3, Isobutane)
(CH4 methane) (CH3CH3, Ethane)
CH3
 Saturated compounds: A saturated compound is a chemical compound that have a chain of

carbon atoms linked together by single bonds.
 Unsaturated compounds: A unsaturated compound is a chemical compound that have a
chain of carbon-carbon atoms linked together by double or triple.
2. Closed Chain (Cyclic) or Ring Compounds: The compounds containing closed rings of carbon
atoms are referred to as cyclic or ring compounds. These are further classified into following
categories.
 Homocyclic or Carbocyclic Compounds: When the ring is entirely made up of carbon atoms,
the compound is said to be carbocyclic compound. Carbocyclic compounds are of two types.
(i) Alicyclic compounds: These compounds contain a ring of three or more carbon atoms only
and possess properties almost similar to those of aliphatic compounds e.g.:
CH2
H2C CH2
CH2 H3C CH2
H2C CH2
H3C CH3 H3C CH2
CH2
Cyclopropane Cyclobutane Cyclohexane

13
(ii) Aromatic compounds: These compounds also possess one or more rings made up of
carbon atoms only and have are characteristic aroma (smell). The parent aromatic
compound, benzene, has a ring of six carbon atoms joined together by alternate single and
double bonds. In general, when the compound contains one or more benzene rings, its is
said to be an aromatic compounds e.g.:
H CH3
C C
H H H H
C C C C
C C C C
H H H H
C C
H H
Benzene Toluene
Aromatic compounds possess properties quite different from those of aliphatic compounds.
 Heterocyclic compounds: These are also cyclic compounds but the ring contains one or more
atoms other than those of carbon. The atoms usually present in ring are of nitrogen, oxygen or
sulphur.
Hydrocarbons and Functional Groups

Hydrocarbons
The organic compounds made up of carbon and hydrogen atoms only are called hydrocarbons.
Hydrocarbons are the simplest organic compounds. Other compounds derived from them are regarded
as the derivatives of their parent hydrocarbons. These compounds are obtained when one or more
hydrogen atoms of a hydrocarbon are replaced by active atoms or groups of atoms called functional
groups.
Hydrocarbons may have straight chains, branched chains or rings.
1. Saturated hydrocarbons or Alkanes : The hydrocarbons in which all the carbon atoms are
linked together by single covalent bonds are called saturated hydrocarbons.
The saturated hydrocarbons are called alkanes. They can be represented by general formula
CnH2n+2, where n is an integer having values 1, 2, 3 …. etc. These are the parent hydrocarbons of all
aliphatic compounds. Some examples of alkanes are as follows.
CH 4 CH 3  CH 3 CH 3  CH 2  CH 3 CH 3  CH 2  CH 2  CH 3
( CH4 , Methane ) ( C 2H6 , Ethane ) ( C3H8 Pr opane ) (C 4 H10 Butane )
 Structure of ethane (C2H6): In ethane (C2H6), the two carbon atoms are linked together by a
single bond leaving each carbon with three valencies unsatisfied. These valencies are satisfied
by hydrogen atoms to form an ethane molecule. Thus ethane has one C–C single bond and six
C–H single bonds as shown below.
H H
H H
× ×
H × C × C × H or H C C H
× × H H
H H
Structure of ethane
(×  electron of carbon)
( electron of hydrogen)

14
 Structure of propane (C3H8): In propane (C3H8), all the three carbon atoms are linked together
by single bonds leaving three valencies each on the first and third carbon atoms unsatisfied and
two valencies on the second carbon atom unsatisfied. These valencies are satisfied by hydrogen
atoms as shown below.
H H H
H H H
× × ×
H × C × C × C H or H C C C H
× × ×
× × × H H H
H H H
Structure of ethane
Thus, a molecule of propane has two C–C and eight C–H single covalent bonds.
2. Unsaturated hydrocarbons: The hydrocarbons which contain one or more double or triple bonds
i.e. multiple bonds between carbon atoms are called unsaturated hydrocarbons.
 Alkenes: Unsaturated hydrocarbons having only one carbon-carbon double bonds are called
alkenes. These can be represented by the general formula CnH2n where n is an integer having
value 2, 3 ….. etc.
 Structure of ethene (ethylene, C2H4): In ethene (C2H4), the two carbon atoms share their
two electrons each to form a C = C double bond. Each carbon is now left with two electrons
which it share with the electrons of two hydrogen atoms to form two C–H single bonds as
shown below.
H H
× × H H
C ×× C or C C
× ×
H H H H
Structure of Ethene or Ethylene
Thus in C2H4, there is one C = C double bond and four C–H single bonds.
 Alkynes: The unsaturated hydrocarbons having only one carbon-carbon triple bond are called
alkynes. The can be represented by the general formula CnH2n–2 where n is an integer having
values 2, 3 ….. etc.
 Structure of ethyne (acetylene, C2H2): In ethylene (C2H2), the two carbon atoms share
their three electrons each to form a C  C triple bond. Each carbon is thus left with one
unshared electron only which it shares with the electron of a hydrogen atom to form a C–H
single bond as shown below.
H × C C × H
or H–CC–H
Structure of Ethyne (Acetylene)
Therefore in C2H2 there is one CC triple bond and two C–H single bonds.

15
COMPETITIVE LEVEL
Alkyl Groups:
When a hydrogen atom is removed from an alkane, the group obtained is called an alkyl group or
alkyl radical e.g. on removing a hydrogen atom from methane (CH4) the resultant left is CH3 – or
methyl group. In methane (CH4), all the four hydrogen atoms are identical. Therefore, removal of
any of the H-atom results in the formation of the same type of methyl group. Similarly in ethane on
removal of one H-atom gives only one ethyl group (i.e., CH3 – CH2 –) because all the six hydrogen
atoms present in it are of the same type. However in propane (CH3CH2CH3) two types of alkyl
groups are formed on removing H-atom e.g.:
CH3
CH and CH3CH2CH2
CH3 Propyl group
Isopropyl group
An alkyl group, in general, is represented by R. Therefore, an alkane can also be written as RH.
 Functional Groups
The chemical nature of an organic compound depends on the presence of a particular active atom or a
group of atoms which largely decides the mode of reactivity of a given compound. The formation of an
organic compound from parent hydrocarbon having functional group X can be shown as follows.
H
RH 
 RX
Hydrocarbon X Organic compound
In the molecule R – X, R represents an alkyl group in aliphatic compounds, whereas in aromatic

compounds, R stands for a aryl group. The group X is called functional group and decides the chemical
nature of the compound. For example, the chemical behaviour of ethyl alcohol (C2H5OH) and
ethylamine (C2H5NH2) are altogether different although they contain the same alkyl group.
CH3  CH2 – OH CH3  CH2 – NH 4

Alkyl Functional Alkyl Functional
group group group group
On the other hand, the properties of ethyl alcohol are almost similar to those of propyl alcohol due the
presence of the same functional group, although they contain different alkyl groups.
CH3  CH 2 — OH CH3  CH 2  CH 2 — OH
Ethyl alcohol Pr opyl alcohol
Similarly propanol (CH3CH2CH2–OH), Propanal (CH3CH2CHO), Propanone (CH3COCH3), Propanoic

acid (CH3CH2COOH) have altogether different nature on account of different functional groups i.e.,
–OH, –CHO, CO and – COOH groups respectively.
Organic compounds have been divided into different families on the basis of functional groups present.
This makes the study of organic compounds much easier, otherwise it would have been a Herculean
task to study five million of organic compounds individually.

16
Table: Some Important Functional Groups and Corresponding Families
Name of the
Functional Corresponding
Hetero atom Structure Functional Common Example
Group Family
Group
Halogen –X –X Halo Halogen CH3–CH 2–Br
(Cl, Br, or I) Compounds (Ethyl bromide or
Bromoethane)
–OH –O–H Hydroxyl Alcohols CH3–CH2–OH
(–ol) (Ethyl alcohol or Ethanol)
–CHO O aldehydic Aldehydes CH3–CHO
C
H
(–al) (Acetaldehyde or Ethanal)
Oxygen CH3
ketonic Ketones
CO C=O C=O
(–one) CH3
(Acetone or Propanone)
–COOH O Carboxylic Carboxylic CH3–COOH
C (–oic acid) acids (Acetic acid or Ethanone
OH
acid)
Homologous Series
The members of a family of organic compounds possess similar or almost similar chemical properties.
Their molecular formulae can be given by a general molecular formula e.g. CnH2n+1OH represents
alcohol family i.e., if n = 1 CH3OH is methyl alcohol, n = 2 C2H5OH is ethyl alcohol.
The members of a family arranged in the order of increasing molar mass gives homologous series. The
various members of a particular homologous series are called homologues.
Homologous Series of Alkanes (CnH2n+2)
Value Molecular Molar IUPAC
Strcutural Formula
of n formula Mass Name
1. CH4 CH4 16 Methane
2. C2H6 CH3–CH3 30 Ethane
3. C3H8 CH3–CH2–CH3 44 Propane
4. C4H10 CH3–CH2–CH2–CH3 58 Butane
5. C5H12 CH3–CH2–CH2–CH2–CH3 72 Pentane
 Characteristics of Homologous Series

The characteristics of a homologous series are as follows:
(i) All the members of a homologous series are represented by the same molecular formula. For
example, all the members of alkane, alkene and alkyne series can be represented by the general
formula CnH2n+2, CnH2n and CnH2n–2 respectively where n may have the value 1, 2, 3, …. For
alkanes and n = 2, 3, 4, …. For salkenes and alkynes.
(ii) The two successive members of a homologous series differ by –CH2 group in their molecular formulae.
(iii) The molecular mass of a compound in the series differs by 14 amu (CH2 = 12 + 2 × 1 = 14) from
that of its nearest neighbour.
(iv) All the members of a series have the same functional group.
(v) The physical properties such as density, melting point, boiling points, solubility, etc., of the members
of a homologous series show almost regular variation in ascending or descending the series.
(vi) Homologues show similar chemical properties.
(vii) The members of a homologous series can be prepared by almost similar methods known as general
methods of preparation.
17
Nomenclature of Organic Compounds
COMPETITIVE LEVEL
 Trivial Names
Initially organic compounds were named on the basis of the source from which they were obtained:
(i) Wood spirit for CH3OH – obtained by
Methyl alcohol destructive
distillation of wood.
(ii) Urea for NH2CONH2 – Obtained from
Urine
(iii) Acetic acid for CH3COOH – obtained from
acetum-vinegar
(iv) Oxalic acid for H2C2O4 – obtained from
oxalis plant
(v) Formic acid for HCOOH – obtained for red ants.
This system of naming the organic compounds was called trivial system and the names thus derived
were called trivial names. However the number of organic compounds increased tremendously towards
the end of nineteenth century and the trivial system could not serve the purpose.
  Primary, secondary, tertiary and quaternary carbon atoms:
(i) C atom attached with one carbon atom is primary C atom or 1º carbon atom.
(ii) C atom attached with two carbon atoms is secondary C atom or 2º carbon atom.
(iii) C atom attached with three carbon atoms is tertiary C atom or 3º carbon atom.
(iv) C atom attached with four carbon atoms is quaternary C atom or 4º carbon atom.
1º
CH 3
3º 2º
– C H  C H2 | 1º
1º 2º
C H3 – C H 2 | – C 4 º  CH 3
1º CH 3 |
1º CH 3
  Primary, Secondary and Tertiary H-atoms:

(i) H-atoms attached on 1ºC atom are primary H-atoms or 1ºH.
(ii) H-atoms attached on 2ºC atom are secondary H-atoms or 2ºH.
(iii) H-atoms attached on 3ºC atom are tertiary H-atoms or 3ºH.
3º
CH 3 – CH 2 – C H  CH 3
1º 2º | 1º
CH 3
1º
  Reactivity order of primary, secondary and tertiary H-atoms :

Relative reactivity order: 3ºH > 2ºH > 1ºH
hv
CH3CH2CH3 + Cl2  CH 3CHClCH3 + CH3 CH 2 CH 2Cl
More yield Less yield

18
IUPAC Name
In 1969, IUPAC (International Union of Pure and Applied Chemistry) convention led out the following
rules to name organic compounds. In 1993, on the basis of recommendations of IUPAC, some changes
were also made at basic level which have also been incorporated.
 General Rules for IUPAC Nomenclature

According to the IUPAC system, the name of an organic compound, in general, has the following three
parts:
1. Word root
2. Suffix
3. Prefix
1. Word root: The word root, a basic unit of the name represents the number of carbon atoms in the
parent chain Parent chain is the longest possible continuous chain of carbon atoms containing
maximum possible functional groups and multiple bonds present in the molecules. For organic
compounds containing parent chains upto four carbon atoms (C1 – C4) special word roots are used,
while for compounds containing parent chains having more than four carbon atoms Greek number
roots are used.
Table : Word Roots for Carbon Chains
Chain Length Word root Chain length Word root
C1 Meth– C6 Hex–
C2 Eth– C7 Hept–
C3 Prop– C8 Oct–
C4 But– C9 Non–
C5 Pent– C10 Dec–
2. Suffix: The suffix in word roots are added to show the main functional group (principal group). The
multiple bonds present in the given compound are indicated by adding specific suffixes to the word
root. The two types of suffix are used for this purpose.
 Primary suffix: The suffix used to represent the multiple bonds i.e. saturation or unsaturation
of carbon atoms present in the parent chain is called a primary suffix.
Table : Primary Suffixes

Primary General
Nature of carbon chain
suffix name
Saturated (C–C) –ane Alkane
Unsaturated, having one
–ene Alkene
double boind (C=C)
Unsaturated, having one
–yne Alkyne
triple bond (CºC)
If the parent carbon chain contains more than one double or triple bonds, their number is
indicated by numerical prefixes such as di (for two), tri (for three), tetra (for four) etc.
e.g.: CH3 – CH=CH2 Propene
CH2 = CH – CH = CH2 Butadiene
19
 Secondary suffix: Secondary suffix represents the nature of principal functional group
present in the compound.
Table: Secondary Suffixes of Some Common Functional Groups
Organic General Functional Seconary IUPAC name word
Compounds formula group suffix root + p-suffix + s-suffix
Alcohol R–OH –OH –ol Alkanol
Aldehyde R–CHO –CHO –al Alkanal
Ketone R–CO–R C O –one Alkanone
Carboxylic
R–COOH –COOH –oic acid Alkanoic acid
acid
Ester RCOOR –COOR –oate Alkanoate
A secondary suffix is added to the primary suffix according to the following convention.
(i) If the secondary suffix begins with a vowel, the terminal 'e' of the primary suffix is
dropped while adding secondary suffix to the primary suffix.
(ii) If the secondary suffix begins with a consonant, the terminal 'e' of the primary suffix is retained
while adding secondary suffix to the primary suffix i.e. alkane nitrile and alkane thiol.
(iii) The terminal 'e' of primary suffix is also retained if some numerical prefixed like di, tri,
etc., are used before the secondary suffix.
(iv) In case of more than one double (=) bonds are present, only 'ne, is replaced by diene, diyne
and so on …. e.g. IUPAC name of CH2 = CH – CH = CH2 is Buta-1,3-diene.
Table: IUPAC Rules for Addition of Primary and Secondary

Suffix in parent hydrocarbon.
IUPAC nadm
Secondary
Compound Word root Primary suffix (Word roto +
suffix
P. suffix + S, suffix)
CH3CH2OH Eth– –ane [Rule (i)] –ol Ethanol
CH3CH2COOH Prop– –ane [Rule (i)] –oic acid Propanoic acid
CH3CH=CH=CH2 But– –ene [Rule (iii)] – Buta-1,2-diene
3. Prefix : The alkyl groups and functional groups other than the principal functional group are
regarded as substituents or side chain. Their presence is indicated by writing suitable prefixes
before the word root.
Table: Some Alkyl Groups and Their Prefixes
Prefix used
Parent
Alkyl group Common name in IUPAC
alkane
name
CH4
CH3– Methyl Methyl
(Methane)
CH3–CH3
CH3–CH2– Ethyl Ethyl
(Ethane)

20
Table : Some Substituents and their Prefixes
Substituent Prefix
–Cl Chloro–
–Br Bromo–
–I Iodo–
–F Fluoro–
–NO Nitroso–
–NO2 Nitro–
–OR Alkoxy–
Therefore in writing the complete IUPAC name of a compound following points should be obeyed.
(i) The arrangement of the different parts of the name is as follows.
Prefix (es) + Word root + Primary suffix + Secondary suffix
(ii) Prefixes are arranged in alphabetical order and are separated by hyphen (–).
(iii) The position of prefixes, double bond, triple bond, or functional group is represented by
putting a suitable Arabic numeral immediately before them.
(iv) In case of cyclic compounds, the prefix cyclo is written immediately before the word root.
Example:
CH3
4 3 2 1
CH3–CH–CH2–CH2OH
3  methyl ....but.... … an * ..........1.......... – ol
(Pr efix ) ( Word root ) ( P. suffix ) ( Position of ( S. suffix )
Functional group )
i.e. IUPAC name of the given compound is 3-methybutan-1- ol

Where, * = if the secondary suffix start with a vowel then terminal 'e' of primary suffix is omitted.
 Nomenclature of Open Chain Hydrocarbons

 Straight Chain Alkanes: The straight chain alkanes are named including the number of carbon
atoms present in them. The names of such compounds end with –ane. Thus, the name of a straight
chain alkane consists only two parts-word root and primary suffix. Thus CH4, C2H6, C3H8 are called
Methane, Ethane and Propane respectively.
 Alkanes and their substituents: In a branched chain alkane, all carbon atoms are not present in
the straight chain. Some of the carbon atoms are presents in side chains at one or more positions.
The side chains i.e., alkyl groups are expressed as prefixes in the IUPAC name of the compound.
(i) Longest chain rule:
 The longest continuous chain of carbon atoms is selected as the parent hydrocarbon. The
compound is then named as a derivative of the parent hydrocarbon. For Example.
1 2 3 4 5 6 3 4 5 6 7
C H 3  C H  C H 2  C H 2  C H 2  C H 3 ( wrong); C H 3  C H  C H 2  C H 2  C H 2  C H 3 ( right);
| |
2
CH 2 CH 2
| |
1
CH 3 CH 3
If more than one set of longest possible chain are possible then the selected longest chain

which should have maximum number of side chain
21
(ii) Lowest number rule:
 The selected chain is numbered in terms of arabic numbers from one end to other.
1 2 3 4  right
e.g.: C H 3 – C H 2 – C H 2 – C H 3
4 3 2 1  wrong
 Lowest number is assigned to the first side chain (alkyl group) or substitutent (–Cl, Br, –I, –NO2).
right  4 3 2 1
e.g.: C H 3 – C H 2 – CH CH3
wrong  1 2 3 4
CH3
4 3 2 1  right
C H 3 – C H 2 – CH CH3
1 2 3 4  wrong
Cl
 If two different substituents are at the same position from opposite ends, lowest number is
given in order of their alphabets.
e.g.:
1 2 3 4 5 6 7  wrong
C H 3 – C H 2 – CH CH2 CH CH2 CH3
7 6 5 4 3 2 1  right
CH3 C2H
(methyl) (ethyl)
1 2 3 4  wrong
e.g.: C H 3  CH CH CH3
4 3 2 1  right
Cl Br
(chloro) (bromo)
 If more than two substituents and side chains are present, the sum of their numbers should
be lowest at the first preference, irrespective of the nature of side chain or substitutents,
3 2 1 1 2 3 4 1 2 3 4 5
4 C CH CH3 H3C–HC CH CH3 H3C–HC CH CH2 CH3
H3 C –
Cl Br Cl I CH3 Cl
2-Chloro-3- 3-Chloro-2-
2-Bromo-3- iodobutane methylpentane
chlorobutane
 If more than one similar alkyl chains or substituents are present names are suitably modified
by putting di, tri, …. terms. While arranging the substituents alphabetically, these prefixes
di, tri etc. are not considered.
1 2 3 4
C H 3 –CH CH CH3 i.e., 2,3-Dimethylbutane
CH3 CH3
 If more than one similar alkyl groups. Or substituents are present, at same position, their
no. is also repeated.
CH3
1 3
C H 3 –2 CH CH3 i.e., 2,2-Di methylpropane
CH3
22
 Alkenes, Alkyes and their derivatives:
(i) Select the longest possible carbon chain having maximum member of unsaturated carbon atoms
or maximum number of double or triple bonds, even if prior rules are violated.
C–C–C–C–C–C
C
 6 with the unsaturated C atom or no double bond. (wrong).

 5 with two unsaturated C atom or one double bond. (right).
 4 with two unsaturated C atom or one double bond. (wrong)
(ii) If double and triple bonds are at the same position from either ends, lowest number is assigned
to the double bond.
5 4 3 2 1
C  C – C –C =C
(iii) In case of unsaturation suffix name of unsaturation is used with hydrocarbon name, i.e.,
In case of double (=) bond 'ane' of hydrocarbon is replaced by 'ene' and
Triple bond () bond 'ane' of hydrocarbon is replaced by 'yne'
(iv) In case of more than one multiple bond of the same kind prefixes like di, tri etc. are used with
the suffix.
CH3–CH=C=CH2 Buta-1,2-diene
Note : If double and triple bonds are present in a compound (i.e., two suffix are to be used for compound
containing both the unsaturation), it is named as Alkenyne.
 For Functional groups:

(i) Select the longest possible carbon chain having maximum number of functional groups even if
prior rules are violated, e.g.:
C–C–C–C– C– C– OH
OH OH
(ii) The carbon atom of functional group is to be included in deciding the longest carbon chain.
C–C–CN 3C atom chain
C–C–C–CHO 4C atom chain
(iii) Lowest number is assigned to functional group even if prior rules are violated.
5 4 3 2 1
C C  C  C C
1 2 3 4 5
1 2 3 4 5
C C C C C
|
CH 3
5 4 3 2 1
C C C C C
| |
CH 3 OH

23
(iv) The order for numbering a carbon chain, thus, follows the order:
(a) Functional group
(b) Unsaturation
(c) Substituents and side chains (or alkyl groups)

7 6 5 4 3 2 1
C C  C  C  C  C  C Lowest number to OH gp.
|
OH
1 2 3 4 3 6 7
C  C  C  C  C  C  C OH at equidistant from two
| ends and thus, Next lowest
OH number to unsaturated
7 6 5 4 3 2 1
C  C  C  C  C  C  C Lowest number to OH gp.
|
OH
7 6 5 4 3 2 1
C C  C  C  C  C  C Lowest number to OH gp.
| |
OH OH
1 2 3 4 5 6 7
C C  C  C  C  C  C OH at equidistant from two
| | ends and thus, next lowest
CH 3 OH number to alkyl group.
Table: Functional groups, their prefixes and suffixes
Functional group Prefix name Suffix name
–COOH carboxy –oic acid
–CHO aldo or formo –al
CO keto or oxo –one
–OH hydroxy –ol
(v) If more than one kind of functional groups are present, the functional group placed above, i.e.,
principal functional group decides suffix name and the others placed below decide prefix name.
CH 3  C  COOH CH 3  C  CH 2 OH CH 3  C  CHO
|| || ||
O O O
2 ketopropanoic acid 1 hydroxypro pan 2 one 2 ketopropanal
(vi) The last 'e' of primary suffix is replaced by the suffix name of functional group.

24
Ex.5 What will the formula and electron dot structure of cyclopentane?
Sol. The general formula of cycloalkanes is CnH2n. Putting n = 5 in this general formula, the formula of
cyclopentance is C5H2×5 = C5H10.
Now carbon has 4 electrons in the valence shell and hydrogen has one. Therefore, to complete its
octet, each carbon shares two of its electrons, one each with two other carbon atoms forming a five-
membered ring. The remaining two electrons of each carbon share one electron each with two
hydrogen atoms. In this way, each hydrogen completes its duplet. The complete electron dot
structure of cyclopentane is shown.
H× H
×
H H
× C
×
C C
H× ×H
H× C C ×H
× ×
H H
Electron dot structure
of cyvlpoentane
Ex.6 Draw the structure of the following compounds:

(i) Ethanoic acid
(ii) Bromopentane
(iii) Butanone
(iv) Hexanal
Are structural isomers possible for bromopentane?
Sol. (i) Ethanoic acid contains carboxyl (COOH) group as the functional group. It contains two carbon
atons including the carbon atom of the carboxyl group. Thus, the structure of ethanoic acid is
H O
H C C O H Ethanoic acid
H
(ii) Bromopentane is obtained by replacing one hydrogen atom of pentane by bromine atom. So, its
structure is
H H H H H
H C C C C C Br Bromopentane
H H H H H
Bromopentane shows structural isomerism due to the presence of bromine on different carbon
atoms of the chain. If we number the carbon atoms of the chain from right to left as 1, 2, 3, 4
and 5 then bromine atom can be resent at three different positions, i.e. 1, 2 and 3. Thus,
bromopentane has three structural isomers. Their structures are:

25
H H H H H H H H H H H H H H H
5 4 3 2 1 5 4 3 2 1 5 4 3 2 1
H C C C C C Br H C C C C C H H C C C C C H
H H H H H H H H Br H H H Br H H
1-Bromopentane 2-Bromopentane 3-Bromopentane
(iii) Butanone contains keto (>C = O) group as the functional group. It contains four carbon atoms
including the carbon atom of the keto group. Since the keto group is a divalent group, it cannot
be placed at the end of the carbon chain. In other words, it has to be present in between the
chain. The only carbon atom at which >C = O group can be placed is position 2. Therefore, the
structure of butanone is as shown below:
H H H
4 3 2 1
H C C C C H Butanone
H H O H
(iv) Hexanal contains aldehyde (CHO) group as the functional group. It contains six carbon
atoms in all, including the carbon atom of the aldehyde group. Since aldehyde is a monovalent
group, it is always present at the end of the carbon chain. If we place the aldehyde group at
position 1, the structure of hexanal is as shown below:
H H H H H H
6 5 4 3 2 1 O
H C C C C C C C Hexanal
H
H H H H H H
Isomerism
Two or more organic compounds having same molecular formula but different properties are known as
isomers and the phenomenon as isomerism. Berzelius used the term first time, i.e., In Greek, iso-same
or equal, meros-apart e.g.:
Molecular formula: C3H7Cl ;
Isomers: CH3CH2CH2Cl and CH3CHClCH3
ISOMERISM
Structura Stereoisomerism
l
Chain Functiona Tautomeris Geometrical Optical

l m
group
Position Metameris
m
Structural Isomerism
Two or more organic compounds having same molecular formula but different structural formula are
known as structural isomers and the phenomenon as structural isomerism. e.g.: CH3CH2CH2Cl and
CH3CHClCH3

26
COMPETITIVE LEVEL
 Types of Structural Isomerism:
1. Chain or Nuclear or Skeleton Isomerism: Two or more organic compounds having same
molecular formula but different structure formula due to different nature of alkyl chain are
known as chain isomers and the phenomenon as chain isomerism.
C4H10: (i) CH3CH 2 CH2 CH3 (ii) (CH ) CHCH
3 2
Butane Isobu tan e or 2 methylpropane
2. Position Isomerism: Two or more organic compounds having same molecular formula but
different structure formula due to different positions of substituents, alkyl groups,
unsaturation or functional groups in carbon chain are known as position isomers and the
phenomenon as position isomerism.
(i) But-1-ene and But-2-ene have the same molecular formula, C4H8 and are position isomers
because they have different positions of double bond as shown below.
C4H8: CH 2  CH  CH2  CH 3
But 1 ene
and CH3 – CH  CH  CH3

But 2  ene
(ii) Similarly, Propan-1-ol and Propan-2-ol have the same molecular formula but possess –OH
groups at different positions. Therefore, they are also position isomers.
C3H8O: CH3  CH2  CH2  OH and CH 3  CH  CH 3
Pr opan 1 ol
|
OH
Pr opan 2  ol
(iii) CH3CH2CH2Cl (1-chloropropane) and CH3CHClCH3(2-chloropropane).

CH3
CH3
(iv) (m-xylene or 1,3-dimethylbenzene) and (p-xylene or 1,4-dimethylbenzene)
CH3 CH3
3. Functional Isomerism: Two or more organic compounds having same molecular formula but
different structure formula due to different nature of functional groups are known as functional
isomers and the phenomenon as functional isomerism.
(i) Ethanol (ethyl alcohol) and methoxymethane (dimethyl ether) both have the same
molecular formula, C2H6O but contain different functional groups. Ethanol contains –OH
group and belongs to the alcohol family, whereas methoxymetahne contains –O– group and
belongs to the ether family.
C2H6O: CH3  CH 2  OH and CH3  O  CH3
Ethanol Methoxymethane
( ethyl alcohol ) ( dimethyl ether )
(ii) Proapanal and Propan-2-one possess the same molecular formula, C3H6O and are
functional isomers because the functional groups present in them are different. The former
H
contains as aldehydic (– | =O) group while the letter possesses a ketonic group ( C = O ).
C
H O
C3H6O: CH3– | and ||
CH 2  C  O CH 3  C  CH 3
Pr opanal Pr opan  2  one

27
Common IUPAC Functional
Molecular Formula
name name group
1. Alcohol and ethers
CH3CH2OH Ethyl alcohol Ethanol –OH
CH3OCH3 Dimethyl ether Methoxymethane –O–
2. Acids and esters
CH3COOH Acetic acid Ethanoic acid –COOH
HCOOHCH3 Methyl formate Methyl methanoate –COOR
3. Aldehydes and ketones
CH3CH2CHO Propyl aldehyde Propanal –CHO
CH3COCH3 Acetone Propanaone C=O

CH2=CHCH2OH Allyl alcohol Prop-2-enol –ene and – ol
4. Cyanides and isocyanides
CH3CN Methyl cyanide Ethane nitrile –CN
CH3NC Methyl isocyanide Methane isonitrile –NC
5. Diene and yne
CH2=CH–CH=CH2 – Buta-1,3-diene diene
CH3–CHºC=CH3 – But-2-yne yne
Chemical Reactions Of Carbon Compounds

1. Combustion or oxidation in air: The burning of a compound in the excess of oxygen or air is
called combustion. It is always exothermic process and releases energy in the form of heat and
light. Combustion reactions are infact the oxidation reactions. e.g.:
C + O2  CO2 + Heat
All allotropic forms of carbon burns in oxygen to give carbon dioxide, liberating heat and light.
Carbon compounds being combustible evolve a large amount of heat and light. This is why carbon
and several carbon compounds are used as fuels.
Saturated hydrocarbons burn with a blue, non-sooty flame due to low percentage of carbon in them
and the entire carbon present in them gets completely oxidized during combustion. Higher alkanes
also burn with a blue non-sooty flame and thus are used as fuels. e.g.:
CH4 (g ) + 2O (g )
2  CO2(g) + 2H2O() + Heat and Light
Methane Oxygen ( from air )
2C 2 H 6 (g ) + 7O2(g)  4CO2 (g) + 6H2O () + Heat and Light

Ethane
C3 H6 (g ) + 5O2(g)  3CO2 + 4H2O() + Heat and Light

Pr opane
Unsaturated hydrocarbons burn in air with a yellow and sooty flame with lots of black smoke, due
to higher percentage carbon in them. During the process of combustion, the entire carbon present
in them is not completely oxidized and the flame contains smoke due to the presence of unburnt
carbon. i.e.,
C 2 H 4 (g ) + 3O (g )
2  2CO2(g) + 2H2O () + Heat and Light
Ethene Oxygen ( from air )
2C 6 H 6 (g) + 15O2 (g)  12CO2(g) + 6H2O (l) + Heat and Light

Benzene

28
 Disadvantages of incomplete combustion of fuel:
(i) Fuel on burning under insufficient supply of oxygen leads to unburnt carbon in the form of
black soot causing air pollution as well as block chimneys in factories.
(ii) The black soot so formed blackens the bottom of cooking utensils.
(iii) Formation of highly dangerous and poisonous carbon monoxide.
(iv) Leading to less heat generation.
COMPETITIVE LEVEL
Formation of Coal and Petroleum

Coal and petroleum are fossil fuels formed from remains of plants and animals which has undergone
many of biological and geological processes over millions of years. It is believed that coal is formed by
the burial of different types of plants that lived millions of yeas ago into the earth on account of natural
disturbances like earthquakes or volcanic eruptions. These underwent slow combustion under pressure
between the layers of earth due to high temperature prevailing inside and changed into coal. Other
carbon forms as oil and gas have been formed in the same way from the remains of dead plants and
animals. The bodies of plants and animals sank in the sea bed and got covered by silt. Bacteria turned
them into oil and gas under the high pressure of sea water. In due course of time, the slit slowly
changed into porous rock. The oil and gas seeped into the pores of the rock and got trapped there. The
natural oil and gas thus came into existence.
2. Oxidation: Oxidation is a process in which oxygen is added to a substance. The substances which
add oxygen to other substances are called oxidizing agents. There are many oxidizing agents such
as alkaline potassium dichromate (K2Cr2O7), nitric acid (HNO3), acidified potassium dichromate
used in organic chemistry. Some common reactions of oxidation are -
(i) CH 2  CH 2 +H2O+(O)Alakline
 kMnO 
4
CH 2  CH 2
Ethene | |
OH OH
Ethylene glycol
(ii) CH  CH + 4(O) Akaline

KMnO 4
   COOH
Ethyne
|
COOH
Oxalic acid
(iii) CH 3CH 2 OH () + (O) Alkaline

  KMnO 4 , Heat
   Alkaline
  KMnO 4 , Heat
   CH 2 COOH() + H2O()
Ethyl alcohol Nascent oxygen Cu tube or acidified K 2Cr2 O 7 , Heat Acetic acid
( From the oxidi sing agent ) ( a carboxylic acid )
(iv) CH 3CHO Alkaline

 KMnO 4 or
  CH 3COOH
Ethanal Acidified K 2 Cr2 O 7 Ethanoic acid
Alkaline KMnO4 or acidified K2Cr2O7 provides oxygen to ethyl alcohol and are known as oxidizing
agents.
3. Addition Reactions: The unsaturated molecules containing a double bond or triple bond show
reactions in which they add molecules across the multiple bonds. These are called addition
reactions.
Addition reactions (e.g.: addition of hydrogen, addition of chlorine, addition of HCl etc.) are the
characteristic reactions of unsaturated compounds. During addition reaction cleavage of one of the
bond (double bond or triple bond) takes place and an attacking species adds to the molecule of an
unsaturated compound at the site of its double or triple bond.

29
 Addition of Hydrogen on Unsaturated Hydrocarbons
Unsaturated hydrocarbons add hydrogen in the presence of a catalyst palladium or nickel. A catalyst is
the substance which alters the rate of a chemical reaction providing a new pathway for reaction
without being used up in the reaction. e.g.:
H H
H H
Nickel
C= + catalyst
H C C H
H C H
H H
Ethane
(Saturated)
H H
Nickel
H–CC–H + 2H2 H C C H
catalyst
Ethyne or
Acetylene H H
(unsaturated) Ethane
(Saturated)
In the first reaction, the molecule of ethene adds one H-atom on each carbon by cleavage of the double
bond. Thus, a hydrogen molecule is added at the site of the double bond and ethene (an unsaturated
hydrocarbon) changes to ethane (a saturated hydrocarbon). In the second reaction, the ethyne molecule
adds two hydrogen molecules at the site of triple bond to form ethane.
The addition of hydrogen to an unsaturated compound to obtain a saturated compound is called
hydrogenation and is largely used in the preparation of margarine (Vegetable Ghee or Vanaspati Ghee)
from edible vegetable oils.
 Hydrogenation of Oils: Vegetable oils such as groundnut oil, soyabean oil, cotton seed oil,
(liquids at room temperature) etc., are unsaturated organic compounds having many double bonds
between the carbon atoms in their molecules.
Hydrogenation of vegetable oils is carried out by heating them with hydrogen in the presence of
nickel as catalyst. In this process, double bonds present in the oil change into single bonds due to
addition of hydrogen at their sites and the oil gets solidified as semi solid mass into a saturated fat
called Vanspati Ghee.
Nickel
Edible oil  H 2 +   Vanaspati Ghee

unsaturated oil Heat ( saturated fat )
( Liquid at room temp.) ( solid at room temp.)
However saturated fats thus obtained by the hydrogenation of edible oils are not good for our
health. Animal fats such as butter, butter oil, desi ghee etc., are also said to be harmful for health.
Therefore, we should prefer to use those edible oils which are least saturated and contain a higher
proportion of unsaturated fatty acids.
 Addition of Cl2 and Br2 on Unsaturated Hydrocarbon
The addition of Cl2 and Br2 takes place in the same manner, but the addition of Br2 on unsaturated
hydrocarbons is a test for unsaturation in molecule. 5 % Br2 – water, a brown solution is used in
addition reaction and the colour of Br2 – water disappears.
CH2 = CH2 + (Br2 - water)CCl
 CH2Br – CH2Br 4
H2C = CH2 + Cl2  CH2Cl – CH2Cl

Similarly on addition of Br2 – water to cooking oil, the colour of Br2 – water disappears. This confirms
that oils contain unsaturated molecules or compounds. On the other hand butter does not decolorizes
Br2 – water showing saturation nature.
30
4. Substitution Reactions : The reactions involving replacement of an atom or group of atoms
present in a compound by some other atom or group without bringing any change in the structure
of the compound, are called substitution reactions.
Saturated hydrocarbons are less reactive and remain inert for most of the reagents. However, they
undergo substitution reaction under specific sets of conditions.
Substitution reactions involving replacement of one or more H-atoms of an alkane with chlorine in
the presence of sunlight are also referred to as chlorination. An alkane on treating with chlorine in
the presence of sunlight shows replacement of all the hydrogen atoms present in the alkane
molecule one by one by chlorine atoms. The reaction is very fast. e.g.:
H H Cl Cl Cl
Cl2 Cl2 Cl2
H C H Sunlight
H C Cl Sunlight
H C Cl Sunlight
H C Cl Sunlight
Cl C Cl
(–HCl) (–HCl) (–HCl) (–HCl)
H H H Cl Cl
Chloromethane Dichloromethane Trichloromethane Tetrachloromethane
(methyl chloride) (chloroform) (carbon tetrachloride)
Chlorination of methane, therefore gives a mixture of chloromethane, dichloromethane,

trichloromethane and tetrachloromethane to give a large number of products.
Ex.5 Why is the conversion of ethanol to ethanoic acid an oxidation reaction?

Sol. A molecule of ethanol contains one oxygen atom while that of ethanoic acid contains two oxygen atoms.
Since oxidation involves addition of oxygen, therefore, conversion of ethanol to ethanoic acid is an
oxidation reaction.
Alternatively, a molecule of ethanol contains six hydrogen atoms while that of ethanoic acid
contains four hydrogen atoms. Since oxidation involves removal of hydrogen, therefore, conversion
of ethanol to ethanoci acid is an oxidation reaction.
O
CH3  CH2  OH + O2 CH3  C  OH + H2O
Ethanol Ethanoic acid
Ex.6 A mixture of oxygen and ethyne is used for welding. Why do you think a mixture of ethyne and air
is not used?
Sol. Ethyne is an unsaturated hydrocarbon, therefore, combustion of ethyne in air produces a yellow
flame with lot of black smoke due to the presence of unburnt carbon in it. Due to this incomplete
combustion, heat produced is also low and a high temperature usually needed for welding cannot
be attained. In order to ensure complete combustion and to obtain a high temperature needed for
welding, a mixture of ethyne and oxygen is used instead of ethyne and air.
2 HC  CH + 5 O2 4 CO2 + 2 H2O + heat and light
Ethyn Oxygen Carbon
e dioxide
Ex.7 Draw all the possible isomers of pentane.

Sol. Isomers of Pentane-C5H12 are:
CH3 CH3
| |
1
CH3  CH2  CH2  CH 2  CH3 CH3 2 CH 3 CH2 4 CH3 and 1
CH3 2 C 3 CH3
n Pentane
( Pentane )
Isopen tan e |
( 2  Methybutan e )
CH3
Neopentan e
( 2, 2  Dimethylpropane)

31
Some Important Organic Compounds
Ethanol (Ethyl Alcohol), C2H5OH
It belongs to alcoholic family of organic compounds.
 Manufacture of Ethanol
(i) By Hydration (hydrolsis) of Ethene: Ethene (ethylene) on reacting with concentrated sulphuric
acid at 353 K, gives ethyl hydrogensulphate. Ethyl hydrogensulphate thus obtained is then
hydrolysed with boiling water or steam to obtain ethyl alcohol.
353 K
CH2CH 2 + H2SO4   CH3CH 2 HSO 4
Ethene 30 atm Ethyl hydrogensu lphate
( ethylene)
CH CH HSO + H 2 O  CH 3CH 2 OH  H 2 SO 4
3 2 4
Ethyl hydrogen sulphate ( boiling ) Ethanol ( ethyl alcohol )
(ii) By Fermentation: The slow decomposition of large, complex molecules of certain organic
compounds into simpler ones by the catalytic activity of enzymes is known as fermentation.
COMPETITIVE LEVEL
 Enzymes are complex biological, nitrogeneous, macromolecules (proteins). These act as catalyst
during biological reactions and are selective and hydrolytic in nature. The optimum temperature
for most of the enzymes is 25º–35ºC. Enzymes are colloidal in nature and pH susceptible.
Preparation of ethanol (ethyl alcohol) from carbohydrates is the oldest known fermentation process.
Even today, fermentation of carbohydrates is one of the most widely used method for the industrial
preparation of ethyl alcohol. The carbohydrates generally used for this purpose are sugars (present
in molasses, grapes, beets etc.) or starch (present in barley, potatoes, rice etc.).
Ethanol form sugars (molasses): Molasses obtained from sugar industry is a dark coloured thick
syrupy liquid and contains unrecovered sugars about 60 %. The extraction of left sugars from
molasses is not profitable. Therefore, it is largely used for the manufacture of ethanol by
fermentation.
The molasses is diluted with water to bring down the concentration of sugars to about 10 %. Some
diluted with a small amount of sulphuric acid to check the growth of unwanted bacteria. Excess of
acid hampers the growth of enzymes needed for fermentation. Now, yeast (enzymes) is added to
this solution and the temperature is maintained at about 30ºC for a few days. Arrangements are
made for proper aeration. The enzymes invertase and zymase present in the yeast convert the
sugars into ethyl alcohol.
C12 H12 O11 + H2O Invertase
  C 6 H12 O 6 + C 6 H12 O 6
Sucrose Glu cos e Fructose
Zymase
C6H12O6  
 2C 2 H5 OH + 2CO2
Ethanol
 Physical Properties of Ethanol (Ethyl Alcohol)

(i) Ethyl alcohol is a colourless liquid having boiling point 351.3 K.
(ii) It possesses characteristic smell and a burning taste.
(iii) It is miscible in water in all proportions. The mixing of ethanol with water is followed by the
evolution of heat and mixture shows contraction in volume, It forces a constant boiling (azeotrpic)
mixture with water (95.6 % alcohol + 4.4 % water) which boils at 351.15 K.
(iv) It has a stimulant effect followed by depressant and anesthetic action on the central nervous system.
(v) It is a good solvent for fats, oils, paints, etc. and for several inorganic substances like NaOH, KOH,
sulphur, phosphorus, etc.

32
 Chemical Properties of Ethanol (Ethyl alcohol)
The chemical properties of ethanol are mainly due to alcoholic (–OH group) group.
(i) Reaction with sodium: Ethanol reacts with sodium (or potassium) to form ethoxide liberating
hydrogen gas. This is a test for alcoholic group.
2C 2 H 5 OH + 2Na  2C 2 H3 ONa + H2
Ethanol Sod. ethoxide
( ethyl alcohol )
Experiment: A small piece of sodium metal is added into 100 % pure ethanol (absolute alcohol)
taken in a dry test tube. Rapid effervescene due to evolution of a gas are noticed. On bringing a
burning splinter near the mouth of test tube the gas coming out of the test tube burns with a
"pop" sound. This indicates that the gas evolved is hydrogen.
(ii) Reaction with concentrated sulphuric acid (dehydration): Ethanol on heating with excess
of concentrated sulphuric acid at 443 K eliminates a water molecule showing dehydration
(removal of water molecule) to form ethene. Concentrated sulphuric acid acts as a dehydrating
agent.
conc . H SO
CH3CH 2 OH    CH2  CH 2  H 2O
2 4
Ethanol 443 K Ethene

( ethyl alcohol ) ( dehydration ) ( ethylene )
COMPETITIVE LEVEL
In excess of ethanol at 140ºC ether is formed.
H 2SO 4
CH3CH2 OH  H OH2CCH3 
140 º C
CH3CH2OCH2CH
(iii) Reaction with ethanoic acid (esterification): Ethanol reacts with ethanoic acid in the
presence of conc. Sulphuric acid to form ethyl ethanoate, (an ester) having fruity smell. This is an
other test for alcoholic group in molecule. The reaction is called esterification as it is
characterized by the formation of an ester.
C2H5O H  HO OCCH3 +conc

. 
H SO
 CH3COOC 2 H 5 + H2O 2 4
Ethanoic acid Ethyl ethanate

( acetic acid ) ( ethyl acetate )
COMPETITIVE LEVEL
(iv) Reaction with halogen acids: It reacts with HCl or HBr in presence of anhydrous ZnCl2 to give
corresponding alkyl halides immediately. For example,
C 2 H 5 OH +HClAnhyd
Heat
 . ZnCl
 C 2 H 5Cl + H2O
 2
Ethanol Chlomethane
( ethyl alcohol ) ( ethyl chloride )
C 2 H 5 OH + HBr Anhyd
Heat
 . ZnCl
 C 2 H 5 Br + H2O
 2
Ethanol Bromoethane
( ethyl alcohol ) ( ethyl bromide )
(v) Combusion: It readily burns in air or oxygen to form carbon dioxide and water.
C 2 H 5 OH  3O 2 
 2CO 2  3H 2 O
Ethanol
( ethyl alcohol )
Ethanol burns with a blue non-sooty flame and liberates lots of heat and is therefore used as a
fuel in spirit lamps. It is a clean fuel as on burning, it gives only carbon dioxide and water which
do not cause much pollution. The fossil fuels such as coal, petrol, etc. produce several harmful
gases on burning which give rise to serious pollution problems.

33
(vi) Oxidation: Oxidising agents such as acidified potassium dischromate oxidise ethanol to ethanal
which further undergoes oxidation to form ethanoic acid.
K 2Cr2O7  H2SO4
CH3CH2 OH +[O]    CH3 CHO + H2O
Ethanol Ethanal
( ethyl alcohol )
K Cr O  H SO
CH3CHO + [O]    CH3 COOH
2 2 7 2 4
Ethanoic acid
( acetic acid )
(vii) Reduction: On reduction with hydroiodic acid in presence of red phosphorus, it gives ethane.
HI  Re d P
C 2 H5 OH   C 2 H 6 + H2O
Ethyl alcohol Ethane
 Uses of Ethanol
(i) in the manufacture of alcoholic beverages.
(ii) as a fuel for spirit lamps and stoves.
(iii) as a solvent for paints, varnishes, lacquers, dyes, cosmetics, perfumes, drugs, tinctures etc.
(iv) as a starting material for the manufacture of ether, chloroform, iodoform, acetaldehyde, acetic acid etc.
(v) as a substitute of petrol.
(vi) as a preservative for biological specimens.
(vii) as an antifreeze for automobile liquid in thermometers and spirit level.
 Commercial forms of Ethanol

(i) Methylated spirit or denatured alcohol: Alcoholic beverages contain ethyl alcohol. Therefore,
the manufacture and sale of ethyl alcohol is controlled by the government and heavy excise duty is
levied on alcoholic beverages. The alcohol used for various other industrial purposes is however
duty free and is sold much cheaper. Therefore, in order to prevent the misuse of cheaper industrial
alcohol for drinking purposes, the industrial alcohol is made unfit for drinking by the addition some
poisonous substances to it.
Industrial alcohol is usually made poisonous by the addition of poisonous substances like methyl
alcohol, pyridine and some colouring matter. Such a sample of alcohol is called methylated spirit or
denatured alcohol. It is poisonous and unfit for drinking.
This process is known as denaturation and alcohol is known as denatured spirit.
COMPETITIVE LEVEL
(ii) Rectified spirit: Rectified spirit is the commercial form of ethanol obtained by the fractional
distillation of wash obtained during the manufacture of ethyl alcohol by fermentation. It is
usually referred to as industrial alcohol. It contains about 95.57 % ethyl alcohol, rest being water.
(iii) Absolute alcohol: It is 100 % pure ethanol obtained by azeotropic distillation of rectified spirit
using benzene. In azeotropic distillation, rectified spirit is mixed with a suitable quantity of
benzene and the mixture is subjected to fractional distillation. The third and the last fraction
obtained at 79.1ºC is absolute alcohol i.e., 100 % ethanol.
(iv) Power alcohol: The alcohol used for the generation of power is called power alcohol (a mixture
of petrol and alcohol in the ratio of 4: 1 and little benzene). Since alcohol does not mix with petrol,
a third solvent such as benzene, ether or tetrahydronapthalene (tetralin) is also added as a
cosolvent. Power alcohol can be used as a substitute for petrol and can meet the everyday
increasing demand of gasoline all over the world.

34
Harmful Effects of Alcohols
All alcoholic beverages (e.g.: Rum, whisky, wine, beer, etc.) contains ethyl alcohol as an essential
constituent. People who consume alcoholic beverages everyday become alcohol adduct. Toxicity of alcohols:
Ethyl alcohol < isopropyl alcohol < methyl alcohol
When taken in small dose, ethanol acts as a stimulant and provides extra energy to the body. But if
used in excess it develops damaging effect in human body e.g. acidity to slow down metabolic processes,
a depressant and anaesthetic action on the central nervous system. This leads to lack of coordination,
mental confusion, drowsiness, lowering of sense of discrimination and finally unconsciousness. Heavy
drinking may even lead to death. One should not consume alcohol due to very harmful effects on
human body.
 Analytical Test for –OH group

(i) Action of Na: Evolution of H2 gas with effervescence. A good test for primary alcoholic groups.
(ii) Action of PCl5: Pass PCl5 to alcohol, warm the solution; outcome of HCl indicates the presence of
–OH group.
(iii) Ceric ammonium nitrate test: Addition of few drops of ceric ammonium nitrate (yellow colour)
to alcohol gives red colour.
Ethanoic Acid (Acetic Acid) CH3COOH

Ethanoic acid commonly known as acetic acid is the main constituent of vinegar and is known since
ancient times. Vinegar widely used as a preservative in pickles, contains 5-8 % of acetic acid solution in
water. Ethanoic acid belongs to the carboxylic acid family of organic compounds and has – COOH
group.
 Manufacture of Ethanoic Acid (Acetic Acid)
(i) From acetylene (ethylene): Acetylene on bubbling through a dilute solution (42 %) of sulphuric
acid containing about 1% mercuric sulphate as catalyst at 333 K, gives acetaldehyde.
Acetaldehyde on oxidation by air in the presence of manganese acetate as catalyst yields acetic
acid.
Dil . H2SO4 1% HgSO4
HC  CH + H2O      CH3CHO
Ethyln e Ethanal
( acetylene) ( acetaldehyde )
2 CH3 CHO +O2 ( CH

COO
 ) Mn
 2CH3 COOH
3 2
Ethanal Ethanoic acid

( acetaldehyde ) ( acetic acid )
This is one of the cheapest methods and gives a very good yield (about 97 %) of acetic acid.
Acetylene used in the method is obtained by treating calcium carbide with water.
(ii) From ethanol: Ethanol (ethyl alcohol) vapours on passing over copper catalyst at 573 K gives
ethanal (acetaldehyde), which on further oxidation by air in the presence of manganese acetate
yields ethanoic acid.
Cu
CH3CH2OH 
 CH3CHO + H2
373 K
( CH COO ) Mn
2CH3CHO + O
2    2CH3COOH 3 2
( Air )

35
COMPETITIVE LEVEL
(iii) Quick vinegar process: Fermented liquors obtained by the fermentation of sugars or starch
contain about 12-15% ethanol. The ethanol present in the fermented liquors is oxidsed by air in
the presence of the enzyme bacterium acetii to give vinegar having 4-7% acetic acid. The process
requires 8-10 days for completion and the maximum concentration of acetic acid that can be
obtained by this method is about 10 %.
(iv) From methanol: Now-a-days ethanoic acid is manufactured by passing carbon monoxide in
methanol in presence of I2-Rh catalyst.
I  Rh
CH3 OH + CO   CH3 COOH 2
methanol Catalyst ethanoic acid
 Physical Properties of Ethanoic acid (Acetic Acid)

(i) Ethanoic acid is a colourless liquid (b. pt 391 K) with a pungent vinegar odour and sour in taste.
(ii) On cooling pure acid below 290 K, it forms ice-like crystals usually called glacial acetic acid
(glacial: ice like).
(iii) It is miscible with water, alcohol and ether in all proportions. It dissolves in water with the
evolution of heat and showing contraction in volume of mixture.
(iv) It is corrosive in nature and produces blisters on the skin.
(v) It dissolves sulphur, iodine and many organic compounds.
 Chemical Properties of Ethanoic Acid (Acetic Acid)

The chemical properties of ethanoic acid are mainly due to the presence of carboxyl (–COOH) group i.e.
functional group present in all carboxylic acids.
(i) Acidic nature: Ethanoic acid shows acidic nature as it turns a blue litmus paper red.
Ethanoic acid is a much weaker acid than hydrochloric acid. All carboxylic acids (organic acids)
are much weaker acids than the mineral acids (e.g.: HCl, H2SO4, etc.)
The mineral acids like HCl are completely ionized and furnish a large number of H+ ions in
solution. On the other hand, carboxylic acids such as CH3COOH being covalent in nature are
weakly dissociated in solution and furnish only a few H+ ions. This is why carboxylic acids are
much weaker acids as compared to the mineral acids.
HCl + H2O  H3O+ + Cl–
CH3COOH + H2O CH3COO– + H+
(ii) Reaction with sodium carbonate and sodium hydrogencarbonates: Ethanoic acid reacts
with sodium carbonate and sodium hydrogencarbonate to yield a salt, effervescence of carbon
dioxide and water.
2CH3COOH + Na 2CO 3  2CH3 COONa + CO 2 + H 2O
Ethanoic acid Sodium Sodium ethanoate Carbon Water
( acetic acid ) carbonate ( Sodium acetate) dioxide
CH3 COOH + NaHCO3  CH3 COONa + CO 2 + H 2O

Ethanoic acid Sodium Sodium ethanoate Carbon Water
( acetic acid ) hydrogenca rbonate ( sodium acetate) dioxide
The evolution of carbon dioxide in the reaction of ethanoic acid with sodium carbonate or sodium
hydrogencarboate is used as identification test for carboxylic group (acidic group).
36
Experiment: Put a little sodium hydrogen carbonate in a boiling tube and set up the apparatus
as shown in figure. Now add 2 mL of dilute ethanoic acid through the thistle funnel. Brisk
effervescence due to evolution of gas is noticed. On passing the gas in freshly prepared limewater
through the delivery tube, the limewater turns milky. Since carbon dioxide turns limewater
milky, it may be concluded that the gas evolved is carbon dioxide.
Thistle funnel
Delivery tube
Cork
Boiling tube Carbon

Dioxide gas
Dilute Limewater
ethanoic
acid
Sodium
Hydrogen
carbonate
Reaction of ethanoic acid with sodium carbonate
Similar observation can be made by taking sodium carbonate in place of sodium hydrogencarbonate.
(iii) Reaction with a base (Neutralisation reaction): Ethanoic acid with alcohols in the presence
an acid (conc. H2SO4) forms salt and water.
CH3 COOH + NaOH  CH3 COONa + H 2O
Ethanoic acid Sodium Sodium ethanoate Water
( acetic acid ) hydroxide ( sodium acetate)
(iv) Reaction with alcohol (Esterification): Reaction of ethanoic acid with alcohol in the presence
an acid (conc. H2SO4 a dehydrating agent) to form ester is called esterification reaction.
O
O
|| CH3–C–O–CH2–CH3+H2O
CH 3  C  OH + CH3CH2 OH
Ethanoic aicd Ethanol conc
. 
H SO
2
 4 Ethylethanoate(ethylacetate)
( acetic acid ) ( ethyl alcohol ) an ester
Experiment: 1 mL of ethanol (absolute alcohol) and 1 mL of glacial acetic acid are taken in a test tube.
Now few drops of concentrated sulphuric acid are added to the mixture and the test tube is warmed in
a water bath as shown in figure. After sufficient warming, the test tube is taken out of water and on
smelling it indicates the presence of an ester in the resulting mixture.
Test tube
Beaker
Reaction mixture
(CH3COOH + CH3CH2OH)
Water + conc. H2SO4
Wire gauze
Formation of ethyl acetate

37
Note: All esters are sweet-smelling substances and are used in making perfumes and as flavouring agents.
The estrification reaction can also be used to identify carboxylic acid.
 Uses of Ethanoic Acid
(i) as a laboratory reagent and as a solvent for carrying out reactions.
(ii) as vinegar.
(iii) in medicine as a local irritant.

(iv) in the manufacture of various dyes, plastics, rayons, silk and perfumes.
(v) as a coagulating agent in rubber industry.
(vi) in the manufacture of acetates, acetone and esters.
 Test for Ethanoic Acid:
Ethanoic acid (acetic acid) gives following test:
(i) Its aqueous solution turns blue litmus red.

(ii) Its aqueous solution gives effervescence with sodium hydrogencarbonate.
(iii) Ferric chloride gives a wine-red colour with neutral solution of acetic acid.
(iv) On heating with ethyl alcohol and a small amount of sulphuric acid, a fruity smell due to formation
of ethyl acetate is noticed.
 Hydrolysis of Ester:
(i) Acidic hydrolysis: An ester on heating with water in the presence of a mineral acid under goes
hydrolysis to form the parent carboxylic acid and alcohol e.g. ethyl ethanoate on heating with water
in the presence of an acid gives ethaboic acid and ethanol back. The reaction is reversible in nature.
H+
CH3COOC 2 H 5 +H2O CH3 COOH + C 2 H 5 OH
Ethyl Ethanoate Ethanoic acid Ethanol
( ethyl acetate) ( acetic acid ) ( ethyl alcohol )
Thus, acidic hydrolysis of an ester is the reverse of the esterfication process.
(ii) Alkaline hydrolysis (Saponification): Hydrolysis of ester carried out in the presence of an
alkali such as sodium hydroxide, gives sodium salt of the parent acid and the parent alcohol.
CH3COOC 2 H 5 + NaOH  CH3 COONa + C 2 H 5 OH

ethyl ethanoate Sodium Sodium ethanoate Ethaol
( ethyl acetate) ( hydroxide ) ( sodium acetate) ( ethyl alcohol )
The alkaline hydrolysis of esters is known as sponification and is used in the preparation of soaps.
Ex.8 How would you distinguish experimentally between an alcohol and a carboxylic acid?
Sol. A carboxylic acid can be distinguished from an alcohol by the following tests:
1. Sodium bicarbonate test. Take a small amount of each compound in a test tube and add to it
an aqueous solution of NaHCO3. The compound which produces brisk effervescence due to the
evolution of CO2 must be a carboxylic acid.

38
2. Alkaline potassium permanganate test. Take a small amount of each compound in a test
tube and add to it a few drops of alkaline potassium permanganate solution and warm. The
compound which discharges the pink colour of alkaline potassium permanganate must be an
alcohol.
Ex.9 How can ethanol and ethanoic acid be differentiated on the basis of their physical and chemical
properties?
Sol. Physical properties. Ethanol and ethanoic acid can be differentiated on the basis of the following
physical properties.
1. Smell. Ethanoic acid has a pungent smell while ethanol has a pleasant smell.
2. Melting point. The melting point of ethanol is much lower (156 K) than that of ethanoic acid (290
K). In winter season, ethanoic acid freezes to form glacier like crystals while ethanol remains as a
liquid.
3. Boiling point. The boiling point of ethanoic acid is much higher (391 K) than that of ethanol (351 K).
4. Action of litmus. Ethanol is a neutral compound and hence it neither turns blue litmus red nor
red litmus blue. In contrast, ethanoic acid is acidic in nature and hence turns blue litmus red.
Chemical properties:
1. Action of sodium carbonate or bicarbonate: Ethanoic acid produces brisk effervescence

due to the evolution of CO2 gas from sodium carbonate or bicarbonate but ethanol does not.
2 CH3COOH + Na2CO3  2 CH3COONa + CO2 + H2O
CH3COOH + NaHCO3  CH3COONa + CO2 + H2O
2. Action of alkaline potassium permanganate. Ethanol discharges the pink colour of KMnO4
but ethanoic acid does not.
Soaps and detergents

Surfactants are the substances which possess surface activity i.e., these reduce the surface tension of
water. Soaps and detergents are the substances which possess surface activity as well as detergency
(cleasing action). The term detergent was originated from Latin word (detergere-to wipe clean).
Soaps and synthetic detergents are commonly used cleaning agents and improve the cleansing
properties of water by easily removing oily dirt present on clothes or skin.
Detergents are of three types:
(i) Anionic detergents
(ii) Cationic detergents
(iii) Non-ionic detergents
 Soaps
Soaps are anionic class of detergents. The commonly used soaps are the sodium or potassium salts of
higher fatty acids such as palmitic acid, stearic acid, oleic acid, etc.

39
COMPETITIVE LEVEL
Preparation of Soaps
The soaps are usually prepared by saponification of oils and fats i.e. the hydrolysis of an oil or fat with
an alkali (sodium hydroxide or potassium hydroxide). Oils and fats are glyceryl esters of fatty acids and
are mixed glycerines.
Sodium soaps are prepared by heating an oil or a gas with aqueous sodium hydroxide solution.
O
CH2–O–C–C17H35
O CH2OH
HC–O–C–C17H35 + 3NaOH  3C17H35COONa + CHOH
O Sodium stearate (soap)
CH2OH
CH2–O–C–C17H35 Glycerol
(or Glycerine)
Glyceryl ester of Steric Acid
(fat)
 Cleasing Action of Soaps

Soaps are widely used as cleansing agents. The cleasing action of a soap is mainly due to its ability
to emulsify the greasy or oil dirt through micelle formation. The mechanism of micelle formation in
soap solution and the cleasing action of soaps are described below.
 Micelle formation in soap solution: A soap can be represented as RCOONa, where R
represents a long chain alkyl group. When dissolved in water soap ionises to give RCOO– ion.
The RCOO– ion possesses two parts-long hydrocarbon chain R (tail) and the polar group –COO–
as shown in figure. The hydrocarbon tail R being non polar and is hydrophobic i.e., water
repelling whereas the –COO– group being polar is hydrophilic i.e., water loving. Therefore
RCOO– ion orients itself in such a way that –COO– end dips in water and the hydrocarbon tail
R orients away from water. The –COO– group of different RCOO– ions tends to stay far away
from one another due to the like charges whereas the R-groups try to approach each other to
form a bunch. This leads to the formation of a micelle as shown in figure.
RCOONa H
2O
 RCOO– + Na+
Na+
Na+
Hydrophobic
Hydrocarbon tail (R) Na+
Hydrophilic
polar
(a) RCOO– ion Na+
(b) Micelle formation by RCOO– ions
Thus, a soap micelle is a negatively charged colloid particle in which the negatively charged –
COO– groups present at the surface whereas the hydrocarbon chains point towards the centre.
The –COO– groups present at the surface of the micelle get surrounded by Na+ ions which tend
to drag the micelle in the bulk of the solution. A micelle may contain as many as 100 molecules
or more. The minimum concentration of soap at which it forms micelle may contain as many as
100 molecules or more. The minimum concentration of soap at which it forms micelle is called
critical micelle concentration or CMC.

40
 The cleasing action of soaps: Water is not capable of wetting oily or greasy substances.
However, the hydrocarbon residue R of the soap anion (RCOO–) can do so. When dirty cloth due
to the deposition (hydrophobic) of RCOO– ion dissolves the non polar impurities of oily or
greasy dirt and encapsulate it in cleaning action of soap is shown in figure.
Greasy
dirt
Soap micelle containing greasy dirt
COMPETITIVE LEVEL
 Limitation of Soaps as Cleansing Agents in Hard Water

No doubt the soaps are capable of removing greasy dirt from a dirty article and are therefore,
widely used as cleansing agents. Their cleansing action with soft water is good but not with hard
water.
The commonly used soaps are the sodium and potassium salt of higher fatty acids. They are soluble
in water to give 100 % ionization. The RCOO– ions so formed shows micellization and give good
lather in solution.
Hard water contains Ca2+ and Mg2+ ions. When a sodium or potassium soap is added to hard water,
it gets converted into a insoluble calcium or magnesium soap.
O
Ca 2 ||
2RCOONa + ( From hard water )  (R  C  O  ) 2 Ca 2  2Na 
Calcium soap
( insoluble in water )
O O
|| ||
2R  C  O  Na  + Mg 2  (R  C  O  )2 Mg 2  2Na 
( From hard water )
Sodium soap Magnesium soap
( so luble in water ) ( insoluble in water )
The conversion of soluble sodium or potassium soaps into insoluble calcium or magnesium soaps in
the presence of hard water, the common soaps are unable to form micelles till all the Ca2+ and Mg2+
ions are removed by using excessive amount of soap. Therefore neither they produce lather with
hard water nor they remove greasy material from cloth. The calcium and magnesium soaps thus
produced, appear on the surface as insoluble sticky grey scum, resulting in decolorisation and
hardening of fabrics. This is why the commonly used sodium and potassium soaps cannot be used
as cleaning agents with hard water.

41
 Synthetic Detergents (Syndets)
Now a days, the term detergent is mainly used to denote synthetic detergents or syndets.
The most commonly used synthetic detergents are either anonic such as sodium salts of long chain
alkyl substituted benzene sulphonic acids or sodium salts of sulphuric acid ester of long chain aliphatic
alcohols or cationic detergents as alkyl ammonium halides.
– + – +
C12H25 SO3Na C12H25–O–SO2–ONa
,
Sodium p-dodecyl Sodium lauryl
benzenesulphonate sulphate
 Detergent vs. Soaps: Synthetic detergents are better cleaning agents than soaps due to the
following reasons.
(i) Detergents can be used both in soft as well as in hard water as their calcium and magnesium
salts are water soluble. On the other hand, soaps form insoluble salts with calcium and
magnesium ions and cannot be used in hard water.
(ii) The aqueous solutions of detergents are usually neutral. Therefore, they do not damage
delicate fabrics and can be used for washing almost all types of fabrics. On the other hand,
aqueous solutions of soap are alkaline and damage delicate fabrics. Therefore, soaps cannot be
used for washing delicate fabrics.
Biodegradable & Non-Biodegradable and Pollution
The detergents having great deal of branching in the hydrocarbon tail are not biodegradable and cause
pollution in rivers and waterways. The presence of side chains in the hydrocarbon tail prevents bacteria
from attacking and breaking the chain. This results in slow degradation of detergent molecules leading to
their accumulation in water.
Efforts are being made of minimize the branching in the detergent molecule in order to make them easily
biodegradable. Since unbranched chains are more easily attacked by the bacteria, the detergents having no
branching or minimum branching are easily biodegraded and pollution is prevented.
Ex.10 Would you be able to check if water is hard by using a detergent?

Sol. No, because detergents produce foam and do not produce curdy white precipitates even in hard water.
Ex.11 People use a variety of methods to wash clothes. Usually after adding the soap, they beat the
clothes on a stone, or beat them with a paddle, scrub with a brush or the mixture is agitated in
a washing machine. Why is this agitation necessary to get clean clothes?
Sol. When dirty clothes are soaked in soap solution, soap micelles containing the oily dirt at the
centre are formed. In these micelles, soap is attracted both by the oily dirt and water. As a
result, the surface tension of water decreases and a stable emulsion of oil in water is formed. To
wash away the loosened dirt particles in form of micelles from the surface of the cloth, it is
either scrubbed mechanically or beaten on a stone or with a paddle or agitated in a washing
machine.
Ex.12 Why does micelle formation take place when soap is added to water? Will a micelle be formed in
other solvents like ethanol also?
Sol. A soap molecule has two ends which have different properties, one end is polar, i.e., hydrophilic
and is water soluble while the other end is non-polar, i.e., hydrophobic, and hence water
insoluble. When soap is added to water, the polar ends dissolve in water while the non-polar ends
dissolve in each other. As a result, spherical ionic micelles are formed. Since soap is soluble in
ethanol, therefore, micelle formation does not occur.

42
EXERCISE-1
 Very Short Answer Type Questions Q.13 Write the molecular formula condensed
formula and structural formula of ethyl
Q.1 Write the formulae of Butanoic acid. alcohol. What is its IUPAC name?
Q.2 Write the IUPAC name of the compound Q.14 How does ethanoic acid react with
CH3COOH. (i) Sodium metal
(ii) Sodium carbonate
Q.3 Complete the reaction (iii) Sodium hydroxide
CH3COOH + NaHCO3 
Q.15 Complete the following reactions:
Q.4 Give the names of the following functional Alk .KMnO
(i) CH3CH2OH   4
group.
(ii) C2H5OH + Na 
– CHO, > CO
(iii) CH3CH2OH + O2 
Q.5 Name the functional groups present in the
following compounds. Q.16 What is an unsaturated hydrocarbon?
(i) CH3CH2CH2COOH Name one such hydrocarbon. Give its
(ii) CH3CH2CH2OH molecular and structural formula.
 Short Answer Type Questions – Type I Q.17 What is meant by saponification? Given an
example.
Q.6 What are hydrocarbons? Give example.
Q.18 What is hydrogenation? What is its industrial
Q.7 What are alkynes? Give example. application?
Q.8 Write the molecular formulae and names of Q.19 An organic compound A having molecular
lower and higher homologoue of C4H6. formula C2H4O2 reacts with sodium metal
and evolves a gas B which readily catches
Q.9 With the help of a balanced chemical
fire. Also reacts with ethanol in the
equation, describe the formation of ester.
presence of concentrated sulphuric acid to
Q.10 How will you show formation of ethylene form sweet smelling substance C used in
molecule with the help of Lewis dot making perfumes.
structure. (i) Identify the compounds A, B and C.
(ii) Write balanced chemical equations to
 Short Answer Type Questions – Type II represents the conversion of:
(a) Compound A into compound B
Q.11 Write the general formulae of alkanes, . (b) Compound A into compound C.
alkenes and alkynes.
Q.20 (i) Why are covalent compounds generally
Q.12 Give an example of each poor conductors of electricity?
(i) a straight chain hydrocarbon (ii) Why are carbon and its compounds
(ii) branched chain hydrocarbon, and used as fuels for most applications?
(iii) ring chain hydrocarbon

43
 Long Answer Type Questions Q.25 A hydrocarbon has three carbon atoms.
Write down its molecular formulae as
Q.21 An organic compound ‘A’ is an essential (i) alkane
constituent of wine and beer. Oxidation of (ii) alkene
‘A’ yields an organic acid ‘B’ which is (iii) alkyne
present in vinegar. Name the compounds (iv) alcohol derivative
‘A’ and ‘B’ and write their structural (v) aldehyde derivative
formula. What happens when ‘A’ and ‘B’ (vi) ketone derivative
react in the presence of an acid catalyst? (vii) acid derivative
Write the chemical equation for the
reaction.
Q.22 What is homologous series? State three

characteristics of homologous series.
Q.23 Which properties of carbon make it a versatile

element. Discuss its bonding in saturated and
unsaturated hydrocarbons.
Q.24 Explain isomerism. State any four

characteristics of isomers. Draw the
structures of possible isomers of butane,
C4H10.

44
EXERCISE-2
Q.1 Which of the following is a crystalline form Q.10 In acetylene, the two carbon atoms are
of carbon? joined by a
(A) Charcoal (B) Coal (A) single bond (B) double bond
(C) Graphite (D) Lamp black (C) triple bond (D) ionic bond
Q.2 Which of the following statements Q.11 Distribution of electrons in carbon is as

regarding graphite is not correct? follow
(A) Graphite is a black and soft crystalline (A) 4, 2
substance (B) 2, 2, 2
(B) Graphite is manufactured by heating
(C) 2, 4
coke at 3000 oC.
(C) Graphite is a bad conductor of heat and (D) None of the above
electricity.
(D) Graphite possesses a metallic lusture. Q.12 Give IUPAC name for the following
compound
Q.3 Organic compounds will always contain CH3
(A) carbon (B) hydrogen
CH3 – C – CH2 – CH3
(C) nitrogen (D) sulphur
CH3
Q.4 Organic compounds are generally - (A) 2, 3 –Dimethyl butane
(A) covalent in nature (B) 3, 3 – Dimethylbutane
(B) ionic in nature (C) 3, 2 – Dimethyl butane
(C) insoluble in organic solvents (D) 2, 2 – Dimethyl butane
(D) soluble in water
Q.13 Which of the compounds is an organic acid?
Q.5 The isomers have the same (A) H — C — H (B) CH3 CCH3
(A) chemical properties
(B) molecular formula O O
(C) physical properties (C) HCOH (D) CH3 CHOH
(D) structural formula
O CH3
Q.6 The number of chain isomers in pentane is

(A) 1 (B) 2 (C) 3 (D) 4 Q.14 Which of the following is an aldehydic
functional group?
O
Q.7 The general formula of alkane series is
(A) Cn H2n–2 (B) Cn H2n (A) — C  C — (B) — C — H
(C) Cn H2n+2 (D) Cn H2n+4 O
Q.8 The next higher homologue of propane is (C) — C — OH (D) — OH

(A) C2H6 (B) C3H4
(C) C4H10 (D) C5H12 Q.15 The IUPAC name of CH2CHO is -
CH3
Q.9 The IUPAC name of CH3CH2CH = CH2 is
(A) propanal
(A) butene (B) isobutene
(B) propanol
(C) butene-2 (D) 3- methy1propene
(C) propanoic aldehyde
(D) 2-methylethanal.

45
Q.16 Identify the 'product' in the reaction Q.25 When a sodium piece is added to acetic acid
conc .H SO
CH 3COOH  C 2 H5 OH    Product
2 4 solution, a gas is evolved. The gas is-
+ H 2O (A) CH4 (B) CO2
(A) alcohol (B) aldehyde (C) H2 (D) O2
(C) ketone (D) ester
Q.26 Esterification is the name given to –
Q.17 The 'product' in the reaction (A) Reaction of an alcohol with a carboxylic
Al O
CH3CH2OH   'product' + H2O is -
2 3 acid in the presence of sulphuric acid
350 º C
(B) Formation of a new substance
(A) alkane (B) alkene (C) A type of addition reaction
(C) alkyne (D) none of these
(D) A type of rearrangement reaction
Q.18 What is formula of carbon tetrachloride ?

Q.27 The slow decomposition of large organic
(A) CCl4 (B) CCl3
molecules by enzymes is known as –
(C) CCl3 (D) CCl
(A) Esterification (B) Fermentation
Q.19 The two consecutive members of a (C) Denaturation (D) Saponification
homologous series differ by –
(A) CH group (B) 14 u Q.28 The substance which is added to ethanol
(C) functional group (D) CH3 group (used in industry for manufacturing
various products) to make it unfit for
Q.20 The molecular formula of benzene is – drinking is –
(A) C6H6 (B) C6H10 (A) Vinegar (B) sodium chloride
(C) C6H12 (D) C6H14 (C) Methanol (D) Ester
Q.21 The IUPAC name of given compound is Q.29 The alcohol obtained from the molasses
CH3  CH  CH 2  CH 3 is –
| (A) Methanol (B) Ethanol
Cl
(C) Propanol (D) Butanol
(A) chloro butane (B) 2-chloro butane
(C) Propane (D) 2-chloro Propane Q.30 Substitution reactions are those reactions
in which –
Q.22 The unique ability of a carbon atom to form (A) saturated hydrocarbons replace the
bonds with other atoms of carbon is called- cations of an inorganic compound
(A) Catenation (B) Allotropy (B) one type of atoms or a group of atoms
(C) Isomerism (D) Isotopes takes the place of another
(C) alkyl group replaces the anion of an
Q.23 Spherical aggregate of soap molecules in inorganic compound
the soap solution is called – (D) alkyl group replaces the cation of an
(A) a micelle (B) an ester inorganic compound
(C) a molasses (D) a vinegar
Q.24 The organic compound, which are non-

biodegradable in nature is –
(A) detergents (B) soaps
(C) esters (D) alcohols

46
EXERCISE-3
Q.1 What is IUPAC name of the following Q.7 Fullerence, an allotrope of carbon contains –
compound CH3–CH2–CH2–OH ? [Haryana NTSE Stqage-1/13]
[Maharastra NTSE Stage-1/13] (A) 30 six membered rings
(A) propan-1-ol (B) Propan-2-ol (B) 24 five membered rings and 10 six
(C) Ethan-1-ol (D) Ethan-2-ol membered rings
(C) 12 five membered rings and 20 six
membered rings
Q.2 In which of the following reactions CO2 is
(D) 18 give membered rings and 15 six
not produced? [NTSE-HR/09] membered rings
(A) burning carbon or its compounds in air
(B) by strongly heating metal carbonates Q.8 The IUPAC name of (CH3)3 C–OH is –
and bicarbonates [Haryana NTSE Stage-l/13]
(C) by reaction of dilute HCl on Ca(OH) 2 (A) 2-Methylpropan-2-ol
(D) by action of dilute H2SO4 on CaCO3 (B) 2-Methylpropan-1-ol
(C) 1,1-Dimethylethanol
Q.3 A gas formed during destructive distillation (D) Butan-1-ol
of wood, turns lime water milky. This gas is -
[NTSE/Delhi/07] Q.9 Unsaturated hydrocarbon is –
(A) CO2 (B) O2 (C) CO (D) NO2 [M.P. NTSE State-I/13]
(A) CH4 (B) C2H6
Q.4 Which of the following contains all methane, (C) C2H4 (D) C2H5OH
hydrogen and carbon monoxide?
[NTSE/Bihar/08/] Q.10 How many isomers are possible for an alkane
(A) Producer gas (B) Water gas having molecular formula C6H14?
(C) Coal gas (D) Bio-gas (A) 3 (B) 4 (C) 5 (D) 6
Q.11 Identify X in the following reaction –

Q.5 When a compound A is heated, a gas B is
CH3–CH2–OH Hot
 ,conc .
evolved which turns lime water milky.  (X) + H2O
H 2SO 4
Compound A is used in the manufacture of [Rajasthan/NTSE Stage-I/16]
glass. Gas B has a property of extinguishing (A) Ethane (B) Methane
fire and it does not support animal life. The (C) Ethene (D) Ethanol
compound A and B are respectively
[Rajasthan/NTSE Stage-II/07] Q.12 Which type of catalyst is ethanol in the
(A) NaHCO3 and CO following reaction?
(B) CaCO3 and CO CHCl3+ O2 C 2 H 5 OH
 2COCl2 + 2HCl
(C) Na2CO3 and CO2
[Rajasthan/NTSE Stage-I/17]
(D) NaHCO3 and CO2 (A) Positive catalyst (B) Negative catalyst
(C) Bio-catalyst (D) Autocatalyst
Q.6 Saloni took a piece of burning charcoal and
collected the gas in a test tube. Then she CH3
poured about 10 ml water in the test tube. Q.13 The IUPAC name of C=CH2 is:
She shaked the test tube and mixed blue CH3
litmus solution in it. What would be the [Rajasthan/NTSE Stage-I/17]
colour of the solution : (A) 1, 1-dimethyl-2-ethene
[Raj/NTSE/09/Stage-II/8.6] (B) 2-methyl-1-propene
(A) blue (B) red (C) 2, 2-dimethyl ethane
(C) mauve (D) colourless (D) 2-methyl prop-2-ene

47
Q.14 Formula of Freon – 112 is: Q.17 To prevent the misuse of the important
[Rajasthan/NTSE Stage-I/17] commercial solvent ethanol is mixed with .....
(A) C2F2Cl4 (B) CF2Cl2 [Maharashtra/NTSE Stage-I/2018-19]
(C) CFCl3 (D) CCl3F (A) Methanol (B) Propanol
(C) Ethanoic acid (D) Propane
Q.15 IUPAC name of isopentane is
[Rajasthan/NTSE Stage-I/18] Q.18 In water purification Fullerene is used as ....
(A) 2-ethyl propane [Maharashtra/NTSE Stage-I/2018-19]
(B) Pentane (A) Fuel (B) Insulator
(C) 2-methyl butane (C) Catalyst (D) Reductant
(D) 2,2-dimethyl propane
Q.19 What is the condensed structural formula
Q.16 Ethane with the molecular formula C2H6 of alcohol ?
has [Delhi/NTSE Stage-I/18] [Maharashtra/NTSE Stage-I/2018-19]
(A) 6 Covalent bond (B) 7 Covalent bond (A) –OH (B) –CHO
(C) 8 Covalent bond (D) 9 Covalent bond (C) –COOH (D) –NH2

48
ANSWER KEY
EXERCISE - 2
Ques. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Ans. C C A A B C C C A C C D C B A
Ques. 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Ans. D B A B A B A A A C A B C B B
EXERCISE – 3
Ques. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Ans. A C A C C B C A C C C B B A C
Ques. 16 17 18 19
Ans. B A C A

49
EXERCISE-1
 Very Short Answer Type Questions Sol.10
H H
× ×
Sol.1 CH3 – CH2 – CH2 – COOH  C4H8O2. C ×× C
× ×
H H
Sol.2 Ethanoic acid.
Sol.3 CH3COOH + NaHCO3 
CH3COONa + H2O + CO2
 Short Answer Type Questions – Type II
Sol.4 Aldehyde  – CHO
Ketone  >C = O Sol.11 CnH2n + 2
CnH2n
Sol.5 (i) Carboxylic acid CnH2n – 2
(ii) Alcohol
H H H
Sol.12 (i) H C C C H
 Short Answer Type Questions – Type I H H H
(CH3CH2CH3, Propene)
Sol.6 Compound of carbon and hydrogen H
CH4, C2H6
H C H
H H
Sol.7 The unsaturated hydrocarbons having one
(ii) H C C C H
carbon-carbon triple bond are called
alkynes. The can be represented by the H H H
general formula CnH2n–2 (CH3–CH –CH3, Isobutane)
Eg. HC  CH (C2H2) CH3
(iii) H3C CH2
Sol.8 Propyne (C3H4) & Pentyne (C5H8).
H3C CH2
Sol.9 Reaction of ethanoic acid with alcohol in
the presence an acid (conc. H2SO4 a Cyclobutane
dehydrating agent) to form ester is called
esterification reaction. Sol.13 Molecular formula of ethyl alcohol – C2H5OH
O or (C2H6O)
|| Condensed formula of Ethyl alcohol –
CH 3  C  OH + CH3CH2 OH CH3CH2OH
Ethanoic aicd Ethanol conc
. HSO
2

4
( ethyl alcohol )
( acetic acid ) Structural formula of ethyl alcohol
O H H
CH3–C–O–CH2–CH3+H2O H C C OH
Ethylethanoate(ethylacetate)
an ester
H H
CAREER POINT _______________________________________________ Carbon

THIS MATERIAL AVAILABLE WITH YOUR NAME AND LOGO CONTACT ME and Its Compounds | 1
7905239992
50
Sol.14 Sol.19
(i) 2CH3COOH + 2 Na  (i) A  CH3COOH
Ethanoic acid Sodium B  H2
( acetic acid )
C  CH3COOC2H5
2CH 3COONa + H2 (ii) (a) Reaction for compound A into compound B
Sodium ethanoate Hydrogen
( sodium acetate ) 2CH3COOH + 2 Na  2CH 3COONa + H 2
Ethanoic acid Sodium Sodium ethanoate Hydrogen
(ii) 2CH3COOH + Na 2 CO3  ( acetic acid ) ( sodium acetate )
Ethanoic acid Sodium
( acetic acid ) carbonate (b) Reaction for compound A into compound C
2CH 3COONa + CO 2 + H 2O O
Sodium ethanoate Carbon Water ||
(Sodium acetate ) dioxide CH 3  C  OH + CH3CH2 OH conc . H SO
Ethanoic aicd Ethanol    2 4
(iii) CH 3COOH + NaOH  CH 3COONa + H 2O ( acetic acid ) ( ethyl alcohol )

Ethanoic acid Sodium Sodium ethanoate Water
( acetic acid ) hydroxide (sodium acetate )
O
CH3–C–O–CH2–CH3+H2O
Alk.KMnO4 Ethylethanoate(ethylacetate)
Sol.15 (i) CH3CH2OH  CH3COOH + H2O
    an ester
(ii) C2H5OH + Na C2H5ONa + H2 Sol.20 (i) Covalent compounds are formed by

(iii) CH3CH2OH + O2  2CO2 + 3H2O sharing of electrons. No charged
particles are formed during the
Sol.16 The hydrocarbons which contain one or formation of covalent compounds hence
these are poor conductors of electricity.
more double or triple bonds i.e. multiple (ii) Carbon and its compounds are used
bonds between carbon atoms are called as fuels because they release a large
unsaturated hydrocarbons. amount of heat and light on burning.
Eg. C2H4
 Long Answer Type Questions
H H
C C Sol.21 Comound A : ethanol : C2H5OH
H H Compound B : ethanoic acid : CH3COOH
Sol.17 The alkaline hydrolysis of esters is known

as sponification and is used in the
preparation of soaps.
CH 3COOC 2 H 5 + NaOH 
ethyl ethanoate Sodium
( ethyl acetate ) ( hydroxide )
CH 3COONa + C 2 H 5OH
Sodium ethanoate Ethaol
( sodium acetate ) ( ethyl alcohol ) When ethanol and ethanoic acid react in
the presence of an acid, a fruity smelling
Sol.18 The addition of hydrogen to an compound is formed. This compound has
unsaturated compound to obtain a ester functional group.
saturated compound is called hydrogenation O
and is largely used in the preparation of ||
CH 3  C  OH + CH3CH2 OH conc . H SO
margarine (Vegetable Ghee or Vanaspati Ethanoic aicd Ethanol    2 4
( acetic acid ) ( ethyl alcohol )

Ghee) from edible vegetable oils.
Nickel
O
Edible oil  H 2 +  
 Vanaspati Ghee
Heat
unsaturate d oil ( saturated fat )
( solid at room temp.)
CH3–C–O–CH2–CH3+H2O
( Liquid at room temp.)
Ethylethanoate(ethylacetate)
an ester

51
Sol.22 The members of a family arranged in the Sol.24 Two or more compounds having identical
order of increasing molar mass gives molecular formulae but different structural
homologous series. The various members of formulae are called isomers and this
a particular homologous series are called phenomenon is called isomerism.
homologues. Four characteristics of isomers are as
The characteristics of a homologous series follows:
are as follows: (i) Isomers can be either straight carbon
(i) The two successive members of a chain or branched carbon chain
homologous series differ by –CH2 group compounds.
in their molecular formulae.
(ii) Isomers have same molecular weight.
(ii) The molecular mass of a compound in
the series differs by 14 amu (CH2 = 12
(iii) They show different chemical properties.
+ 2 × 1 = 14) from that of its nearest
(iv) Isomers may or may not have same
neighbour.
functional group.
(iii) All the members of a series have the
Two isomers of butane (C4H10) are as
same functional group.
(iv) Homologues show similar chemical follows:
properties. CH 3
|
CH 3  CH 2  CH 2  CH 3 , 1 CH 3  2 CH  3 CH 3
Sol.23 The four main characteristic properties of n  Bu tan e Isobu tan e
( Bu tan e ) ( 2  Methypropa ne )
carbon atom which make it a versatile
element.
1. Catenation : This unique property of Sol.25 (i) C3H8
self-linking of carbon atoms through (ii) C3H6
covalent bonds to form long straight or (iii) C3H4
branched chains and rings of different (iv) C3H7OH
sizes is called catenation. (v) C2H5CHO
2. Tetra-valency of carbon: Carbon has (vi) C3H6O
a valency of four. Therefore, it is (vii) C2H5COOH
capable of bonding with four other
atoms.
3. Tendency to form multiple bonds:
Due to small size, carbon also forms
multiple (double and triple) bonds with
other carbon atoms, oxygen, sulphur and
nitrogen.
4. Isomerism : Two or more organic
compounds having same molecular
formula but different properties are
known as isomers and the phenomenon
as isomerism.
In saturated hydrocarbons there is a
single covalent bond between two
carbon atoms while in unsaturated
hydrocarbons there is atleast one
double or triple covalent bond between
two carbon atoms

7905239992
52
EXERCISE-2
Sol.1 [C] Sol.11 [C]
Graphite is a form of crystalline carbon 6C  2, 4
because in this each carbon atom is
covalently bonded. Sol.12 [D]
C
Sol.2 [C] 2 3
Graphite is a good conductor of electricity C–C–C–C
1 4
due to free electron. C
2,2-Dimethyl butane
Sol.3 [A]
A compound which contain a carbon is
called organic compound. Sol.13 [C]
Organic acid contain –COOH group.
Sol.4 [A]
Organic compound made by carbon atom Sol.14 [B]
and carbon atom have covalent bond O
character.
— C — H group containing compound are
Sol.5 [B] called aldehyde.
Two compounds which have same
molecular formula but different in Sol.15 [A]
structure is called isomers. O
Sol.6 [C] CH3 – CH2 – C – H Propanal

3 2 1
Chain isomers in pentane :
C
| Sol.16 [D]
C–C–C–C C–C–C–C conc.H SO
C–C–C–C | | CH3COOH + C2H5OH  2
4
C C O
Pentane 2-methyl butane 2,2-dimethyl CH3 – C – O – C2H5 + H2O
propane
Ester
Sol.7 [C]
Sol.17 [B]
Alkane have formulae : Cn H2n+2
Dehydration process
Al O
CH2 – CH2 350
  CH2 = CH2 + H2O
2 3
Sol.8 [C] ºC
| | Alkene
Propane  C3H3 H OH
+CH2 (for homologous series
add +CH2 or 14 amu)
C4H10 Sol.18 [A]
Carbon tetra chloride  CCl4
Sol.9 [A] Cl
|
4 3 2 1
CH3  CH2  CH  CH2 Cl  C  Cl
|
But-1-ene or Butene Cl
Sol.10 [C] Sol.19 [B]

CH  CH Homologous series have difference of –CH2
Triple bond group or 14 unit mass.

53
Sol.20 [A] Sol.27 [B]
Benzene  C6H6 Break down (decomposition) of large
H compound by slow process is called
fermentation.
C
H H
C C
Sol.28 [C]
Methanol is used in industry for poising
C C alcohol.
H H
C
H Sol.29 [B]
Ethanol obtained from the molasses
Zymase
Sol.21 [B] C6H12O6   2C2H5OH + 2CO2.
1 2 3 4
CH3  CH  CH2  CH3
| Sol.30 [B]
Cl In substitution reaction one atom replaced
2-chloro butane. by another atom.
Sol.22 [A]
Tendency of a carbon to form a bond by
itself is called catenation.
Sol.23 [A]
Spherical aggregate of soap molecules in
the soap solution is called micelle.
Sol.24 [A]
Detergents are non-biodegradable in nature.
Sol.25 [C]
When metal react with acid hydrogen gas
evolved.
Sol.26 [A]
Conc. H2SO 4
Alcohol + Acid      Ester.
Esterification

7905239992
54
EXERCISE-3
Sol.1 [A] Sol.11 [C]

CH3  CH2  CH2  OH H
CH3CH2–OH  (X) + H2O
3 2 1 
Propan-1-ol 
    CH2 = CH2
Sol.2 [C] (Ethene)
HCl + Ca(OH)2  CaCl2 + H2O
Sol.12 [B]
Sol.3 [A] C H OH
CHCl3 + O2   2COCl2 + 2HCl
2 5
Ca(OH)2 + CO2  CaCO3

Negative catalyst : As it can slow down the
rate of reaction. That’s why it is used for.
Sol.4 [C]
Coal gas  CH4 + H2 + CO
Sol.13 [B]
3 2 1
Sol.5 [C] CH3  C  CH2
Na2CO3(A), used in manufacturing of glass |
and on heating releases CO2(B). CH3

Na2CO3  Na2O + CO2 2-Methyl-1-propene
Sol.6 [B] Sol.14 [A]

C + O2  CO2 (Acidic oxide) Freon – 112 :
+ H2O  H2CO3 (Acid) C2F2Cl4
Acid turns blue litmus red. 1,1,2,2-Tetrachloro-2,2-Difluoroethane.
Sol.7 [C] Sol.15 [C]

Fullerence : It is of 12, 5 membered rings CH3
and 20, 6 membered rings. |
CH3  C  CH2  CH3
|
Sol.8 [A]
H
CH3
|
H3C – C – OH Sol.16 [B]
| H H
CH3
3 2
2-Methyl-propanol
H C C H
6 4 1
Sol.9 [C] 5 7
Unsaturated means ‘=’ or ‘’ H H
H H 7 Covalent bond.
C=C
H H
Sol.17 [A]
Sol.10 [C] Ethonol is mixed with methanol in
C–C–C–C–C–C industrial use.
C–C–C–C–C C–C–C–C Sol.18 [C]

| | |
C C C Catalyst  Fullerene
(C60)
C
| Sol.19 [A]
C–C–C–C–C C–C–C–C
| | –OH  Alcoholic functional group.
C C
5 possible.

55

Carbon & Its Compounds CLASS X

Uploaded by

Copyright:

Available Formats

Carbon & Its Compounds CLASS X

Uploaded by

Document Information

Original Description:

Original Title

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

Carbon & Its Compounds CLASS X

Uploaded by

Copyright:

Available Formats

YOUR LOGO

 Bonding in Carbon: The Covalent Bond

Bonding in Carbon Allotropes of Isomerism in Important Carbon

Graphite Lamp black

2 | Carbon and Its Compounds ________________________________________________CAREER POINT

Bonding in Carbon-The Covalent Bond

 Formation of Covalent Bond

Hydrogen atomHydrogen atom Hydrogen molecule

Nitrogen atomNitrogen atom Nitrogen molecule

4 | Carbon and Its Compounds ________________________________________________CAREER POINT

 Properties of Covalent Compounds

CAREER POINT _______________________________________________ Carbon and Its Compounds | 5

S.No. Ionic Compounds Covalent Compounds

6 | Carbon and Its Compounds ________________________________________________CAREER POINT

Oxygen atom Oxygen atom Oxygen molecule

8 | Carbon and Its Compounds ________________________________________________CAREER POINT

Table: Difference in the properties of

The soccer ball structure of

Note: C60 molecules is made of 20 hexagons and 12 pentagons.

CAREER POINT _______________________________________________ Carbon and Its Compounds | 9

 Amorphous Forms of Carbon

Versatile Nature of Carbon

10 | Carbon and Its THIS

Three-membered ring Four-membered ring

Five-membered ring Six-membered ring

CAREER POINT ______________________________________________ Carbon and Its Compounds | 11

Ex.4 Why carbon shows the property of catenation?

Ex.5 Name the first organic compound synthesized in the laboratory..

12 | Carbon and Its THIS

Open chain or Closed chain (Cyclic)

Homocyclic or Carbocylic Heterocyclic

Alicyclic Aromatic Alicyclic Aromatic

 Saturated compounds: A saturated compound is a chemical compound that have a chain of

CAREER POINT ______________________________________________ Carbon and Its Compounds | 13

Hydrocarbons and Functional Groups

14 | Carbon and Its THIS

Structure of Ethene or Ethylene

Structure of Ethyne (Acetylene)

CAREER POINT ______________________________________________ Carbon and Its Compounds | 15

In the molecule R – X, R represents an alkyl group in aliphatic compounds, whereas in aromatic

CH3  CH2 – OH CH3  CH2 – NH 4

Similarly propanol (CH3CH2CH2–OH), Propanal (CH3CH2CHO), Propanone (CH3COCH3), Propanoic

–OH, –CHO, CO and – COOH groups respectively.

16 | Carbon and Its THIS

 Characteristics of Homologous Series

  Primary, Secondary and Tertiary H-atoms:

  Reactivity order of primary, secondary and tertiary H-atoms :

18 | Carbon and Its THIS

 General Rules for IUPAC Nomenclature

Table : Primary Suffixes

Ketone R–CO–R C O –one Alkanone

Table: IUPAC Rules for Addition of Primary and Secondary

20 | Carbon and Its THIS

i.e. IUPAC name of the given compound is 3-methybutan-1- ol

 Nomenclature of Open Chain Hydrocarbons

 6 with the unsaturated C atom or no double bond. (wrong).

 For Functional groups:

C–C–CN 3C atom chain