NCERT Book Class 11 Chemistry Chapter 9 Hydrocarbons

Hydrocarbons 295

Unit 9

Hydrocarbons

Hydrocarbons are the important sources of energy.

After studying this unit, you will be
able to
• name hydrocarbons according to The term ‘hydrocarbon’ is self-explanatory which means
IUPAC system of nomenclature; compounds of carbon and hydrogen only. Hydrocarbons
• recognise and write structures play a key role in our daily life. You must be familiar
of isomers of alkanes,
with the terms ‘LPG’ and ‘CNG’ used as fuels. LPG is the
alkenes, alkynes and aromatic
abbreviated form of liquified petroleum gas whereas CNG
hydrocarbons;
• learn about various methods of
stands for compressed natural gas. Another term ‘LNG’
preparation of hydrocarbons; (liquified natural gas) is also in news these days. This is
• distinguish between alkanes, also a fuel and is obtained by liquifaction of natural gas.
alkenes, alkynes and aromatic Petrol, diesel and kerosene oil are obtained by the fractional
hydrocarbons on the basis of distillation of petroleum found under the earth’s crust.
physical and chemical properties; Coal gas is obtained by the destructive distillation of
• draw and differentiate between coal. Natural gas is found in upper strata during drilling
various conformations of ethane; of oil wells. The gas after compression is known as
• appreciate the role of compressed natural gas. LPG is used as a domestic fuel
hydrocarbons as sources of
with the least pollution. Kerosene oil is also used as a
energy and for other industrial
applications;
domestic fuel but it causes some pollution. Automobiles
• predict the formation of need fuels like petrol, diesel and CNG. Petrol and CNG
the addition products of operated automobiles cause less pollution. All these fuels
unsymmetrical alkenes and contain mixture of hydrocarbons, which are sources of
alkynes on the basis of electronic energy. Hydrocarbons are also used for the manufacture
mechanism; of polymers like polythene, polypropene, polystyrene etc.
• comprehend the structure of Higher hydrocarbons are used as solvents for paints. They
benzene, explain aromaticity are also used as the starting materials for manufacture
and understand mechanism of many dyes and drugs. Thus, you can well understand
of electrophilic substitution
the importance of hydrocarbons in your daily life. In this
reactions of benzene;
• predict the directive influence of
unit, you will learn more about hydrocarbons.
substituents in monosubstituted
9.1 CLASSIFICATION
benzene ring;
• learn about carcinogenicity and Hydrocarbons are of different types. Depending upon
toxicity. the types of carbon-carbon bonds present, they can
be classified into three main categories – (i) saturated

Unit 9.indd 295 10/10/2022 10:37:52 AM