NCERT book Class 8 Science - Coal And Petroleum

 Page 1


COAL AND PETROLEUM
COAL AND PETROLEUM
Can air, water and soil be exhausted
by human activities? You have already
studied about water in Class VII. Is water
a limitless resource?
In the light of the availability of
various resources in nature, natural
resources can be broadly classified
into two kinds:
(i) Inexhaustible Natural Resources:
These resources are present in unlimited
quantity in nature and are not likely to
be exhausted by human activities.
Examples are: sunlight, air.
(ii) Exhaustible Natural Resources: The
amount of these resources in nature is
limited. They can be exhausted by
human activities. Examples of these
resources are forests, wildlife, minerals,
coal, petroleum, natural gas etc.
Activity 3.2
(It is a group activity)
Take some containers. Fill them
with  popcorn/peanuts/roasted
gram/toffees. Divide students into
groups of seven each. Further divide
each group into three subgroups
containing 1, 2 and 4 students.
Label them as first, second
and third generation respectively.
W
e use various materials for our
basic needs. Some of them are
found in nature and some
have been made by human efforts.
Activity 3.1
Make a list of various materials used
by us in daily life and classify them
as natural and man-made.
Natural Man-made
Can we use all our
natural resources
forever ?
Does this list include air, water, soil
and minerals? Since all these are
obtained from nature, they are called
natural resources.
2024-25
Page 2


COAL AND PETROLEUM
COAL AND PETROLEUM
Can air, water and soil be exhausted
by human activities? You have already
studied about water in Class VII. Is water
a limitless resource?
In the light of the availability of
various resources in nature, natural
resources can be broadly classified
into two kinds:
(i) Inexhaustible Natural Resources:
These resources are present in unlimited
quantity in nature and are not likely to
be exhausted by human activities.
Examples are: sunlight, air.
(ii) Exhaustible Natural Resources: The
amount of these resources in nature is
limited. They can be exhausted by
human activities. Examples of these
resources are forests, wildlife, minerals,
coal, petroleum, natural gas etc.
Activity 3.2
(It is a group activity)
Take some containers. Fill them
with  popcorn/peanuts/roasted
gram/toffees. Divide students into
groups of seven each. Further divide
each group into three subgroups
containing 1, 2 and 4 students.
Label them as first, second
and third generation respectively.
W
e use various materials for our
basic needs. Some of them are
found in nature and some
have been made by human efforts.
Activity 3.1
Make a list of various materials used
by us in daily life and classify them
as natural and man-made.
Natural Man-made
Can we use all our
natural resources
forever ?
Does this list include air, water, soil
and minerals? Since all these are
obtained from nature, they are called
natural resources.
2024-25
These sub-groups represent the
consumers. As population is
growing, second and third
generations have larger number of
consumers.
Put one full container for each
group on a table. Ask consumers of
the first generation from each group
to consume eatables from the
container of their group. Now, ask
the second generation consumers
from each group to do the same. Ask
students to observe carefully the
availability of eatables in each
container. If some thing is left in the
containers, ask third generation
from each group to consume it. Now,
finally observe whether all the
consumers of the third generation
got the eatables or not. Also observe
if anything is still left in any of the
containers.
Assume that the eatables in the
container represent the total
availability of an exhausible natural
resource like coal, petroleum or
natural gas. Each group may have a
different consumption pattern. Are
the earlier generations of any group
too greedy?  It may be that the earlier
generations in some groups were
concerned about the coming
generation(s) and left something for
them.
In this chapter we will learn about
some exhaustible natural resources
like coal, petroleum and natural gas.
These were formed from the dead
remains of living organisms (fossils).
So, these are all known as fossil
fuels.
3.1 Coal
You may have seen coal or heard about
it (Fig. 3.1). It is as hard as stone and is
black in colour.
Fig. 3.1: Coal
Coal is one of the fuels used to cook
food. Earlier, it was used in railway
engines to produce steam to run the
engine. It is also used in thermal power
plants to produce electricity. Coal is also
used as a fuel in various industries.
Story of Coal
Where do we get
coal from and how
is it formed?
About 300 million years ago the
earth had dense forests in low lying
wetland areas. Due to natural processes,
like flooding, these forests got buried
under the soil. As more soil deposited
over them, they were compressed. The
temperature also rose as they sank
deeper and deeper. Under high pressure
and high temperature, dead plants got
slowly converted to coal. As coal
contains mainly carbon, the slow
process of conversion of dead vegetation
into coal is called carbonisation. Since
it was formed from the remains of
vegetation, coal is also called a fossil fuel.
A coal mine is shown in Fig. 3.2.
COAL AND PETROLEUM 33
2024-25
Page 3


COAL AND PETROLEUM
COAL AND PETROLEUM
Can air, water and soil be exhausted
by human activities? You have already
studied about water in Class VII. Is water
a limitless resource?
In the light of the availability of
various resources in nature, natural
resources can be broadly classified
into two kinds:
(i) Inexhaustible Natural Resources:
These resources are present in unlimited
quantity in nature and are not likely to
be exhausted by human activities.
Examples are: sunlight, air.
(ii) Exhaustible Natural Resources: The
amount of these resources in nature is
limited. They can be exhausted by
human activities. Examples of these
resources are forests, wildlife, minerals,
coal, petroleum, natural gas etc.
Activity 3.2
(It is a group activity)
Take some containers. Fill them
with  popcorn/peanuts/roasted
gram/toffees. Divide students into
groups of seven each. Further divide
each group into three subgroups
containing 1, 2 and 4 students.
Label them as first, second
and third generation respectively.
W
e use various materials for our
basic needs. Some of them are
found in nature and some
have been made by human efforts.
Activity 3.1
Make a list of various materials used
by us in daily life and classify them
as natural and man-made.
Natural Man-made
Can we use all our
natural resources
forever ?
Does this list include air, water, soil
and minerals? Since all these are
obtained from nature, they are called
natural resources.
2024-25
These sub-groups represent the
consumers. As population is
growing, second and third
generations have larger number of
consumers.
Put one full container for each
group on a table. Ask consumers of
the first generation from each group
to consume eatables from the
container of their group. Now, ask
the second generation consumers
from each group to do the same. Ask
students to observe carefully the
availability of eatables in each
container. If some thing is left in the
containers, ask third generation
from each group to consume it. Now,
finally observe whether all the
consumers of the third generation
got the eatables or not. Also observe
if anything is still left in any of the
containers.
Assume that the eatables in the
container represent the total
availability of an exhausible natural
resource like coal, petroleum or
natural gas. Each group may have a
different consumption pattern. Are
the earlier generations of any group
too greedy?  It may be that the earlier
generations in some groups were
concerned about the coming
generation(s) and left something for
them.
In this chapter we will learn about
some exhaustible natural resources
like coal, petroleum and natural gas.
These were formed from the dead
remains of living organisms (fossils).
So, these are all known as fossil
fuels.
3.1 Coal
You may have seen coal or heard about
it (Fig. 3.1). It is as hard as stone and is
black in colour.
Fig. 3.1: Coal
Coal is one of the fuels used to cook
food. Earlier, it was used in railway
engines to produce steam to run the
engine. It is also used in thermal power
plants to produce electricity. Coal is also
used as a fuel in various industries.
Story of Coal
Where do we get
coal from and how
is it formed?
About 300 million years ago the
earth had dense forests in low lying
wetland areas. Due to natural processes,
like flooding, these forests got buried
under the soil. As more soil deposited
over them, they were compressed. The
temperature also rose as they sank
deeper and deeper. Under high pressure
and high temperature, dead plants got
slowly converted to coal. As coal
contains mainly carbon, the slow
process of conversion of dead vegetation
into coal is called carbonisation. Since
it was formed from the remains of
vegetation, coal is also called a fossil fuel.
A coal mine is shown in Fig. 3.2.
COAL AND PETROLEUM 33
2024-25
SCIENCE 34
Fig. 3.2: A coal mine
Coal Gas
Coal gas is obtained during the
processing of coal to get coke. It is used
Coal gas was used for street lighting
for the first time in London in 1810
and in New York around 1820. Now a
days, it is used as a source of heat
rather than light.
These days, bitumen, a petroleum
product, is used in place of coal-tar
for metalling the roads.
Fig. 3.3: Coal tar
When heated in air, coal burns and
produces mainly carbon dioxide gas.
Coal is processed in industry to get
some useful products such as coke, coal
tar and coal gas.
Coke
It is a tough, porous and black
substance. It is an almost pure form of
carbon. Coke is used in the manufacture
of steel and in the extraction of many
metals.
Coal Tar
It is a black, thick liquid (Fig. 3.3) with
an unpleasant smell. It is a mixture of
about 200 substances. Products
obtained from coal tar are used as
starting materials for manufacturing
various substances used in everyday
life and in industry, like synthetic
dyes, drugs, explosives, perfumes,
plastics, paints, photographic materials,
roofing materials, etc. Interestingly,
naphthalene balls used to repel moths
and other insects are also obtained from
coal tar.
2024-25
Page 4


COAL AND PETROLEUM
COAL AND PETROLEUM
Can air, water and soil be exhausted
by human activities? You have already
studied about water in Class VII. Is water
a limitless resource?
In the light of the availability of
various resources in nature, natural
resources can be broadly classified
into two kinds:
(i) Inexhaustible Natural Resources:
These resources are present in unlimited
quantity in nature and are not likely to
be exhausted by human activities.
Examples are: sunlight, air.
(ii) Exhaustible Natural Resources: The
amount of these resources in nature is
limited. They can be exhausted by
human activities. Examples of these
resources are forests, wildlife, minerals,
coal, petroleum, natural gas etc.
Activity 3.2
(It is a group activity)
Take some containers. Fill them
with  popcorn/peanuts/roasted
gram/toffees. Divide students into
groups of seven each. Further divide
each group into three subgroups
containing 1, 2 and 4 students.
Label them as first, second
and third generation respectively.
W
e use various materials for our
basic needs. Some of them are
found in nature and some
have been made by human efforts.
Activity 3.1
Make a list of various materials used
by us in daily life and classify them
as natural and man-made.
Natural Man-made
Can we use all our
natural resources
forever ?
Does this list include air, water, soil
and minerals? Since all these are
obtained from nature, they are called
natural resources.
2024-25
These sub-groups represent the
consumers. As population is
growing, second and third
generations have larger number of
consumers.
Put one full container for each
group on a table. Ask consumers of
the first generation from each group
to consume eatables from the
container of their group. Now, ask
the second generation consumers
from each group to do the same. Ask
students to observe carefully the
availability of eatables in each
container. If some thing is left in the
containers, ask third generation
from each group to consume it. Now,
finally observe whether all the
consumers of the third generation
got the eatables or not. Also observe
if anything is still left in any of the
containers.
Assume that the eatables in the
container represent the total
availability of an exhausible natural
resource like coal, petroleum or
natural gas. Each group may have a
different consumption pattern. Are
the earlier generations of any group
too greedy?  It may be that the earlier
generations in some groups were
concerned about the coming
generation(s) and left something for
them.
In this chapter we will learn about
some exhaustible natural resources
like coal, petroleum and natural gas.
These were formed from the dead
remains of living organisms (fossils).
So, these are all known as fossil
fuels.
3.1 Coal
You may have seen coal or heard about
it (Fig. 3.1). It is as hard as stone and is
black in colour.
Fig. 3.1: Coal
Coal is one of the fuels used to cook
food. Earlier, it was used in railway
engines to produce steam to run the
engine. It is also used in thermal power
plants to produce electricity. Coal is also
used as a fuel in various industries.
Story of Coal
Where do we get
coal from and how
is it formed?
About 300 million years ago the
earth had dense forests in low lying
wetland areas. Due to natural processes,
like flooding, these forests got buried
under the soil. As more soil deposited
over them, they were compressed. The
temperature also rose as they sank
deeper and deeper. Under high pressure
and high temperature, dead plants got
slowly converted to coal. As coal
contains mainly carbon, the slow
process of conversion of dead vegetation
into coal is called carbonisation. Since
it was formed from the remains of
vegetation, coal is also called a fossil fuel.
A coal mine is shown in Fig. 3.2.
COAL AND PETROLEUM 33
2024-25
SCIENCE 34
Fig. 3.2: A coal mine
Coal Gas
Coal gas is obtained during the
processing of coal to get coke. It is used
Coal gas was used for street lighting
for the first time in London in 1810
and in New York around 1820. Now a
days, it is used as a source of heat
rather than light.
These days, bitumen, a petroleum
product, is used in place of coal-tar
for metalling the roads.
Fig. 3.3: Coal tar
When heated in air, coal burns and
produces mainly carbon dioxide gas.
Coal is processed in industry to get
some useful products such as coke, coal
tar and coal gas.
Coke
It is a tough, porous and black
substance. It is an almost pure form of
carbon. Coke is used in the manufacture
of steel and in the extraction of many
metals.
Coal Tar
It is a black, thick liquid (Fig. 3.3) with
an unpleasant smell. It is a mixture of
about 200 substances. Products
obtained from coal tar are used as
starting materials for manufacturing
various substances used in everyday
life and in industry, like synthetic
dyes, drugs, explosives, perfumes,
plastics, paints, photographic materials,
roofing materials, etc. Interestingly,
naphthalene balls used to repel moths
and other insects are also obtained from
coal tar.
2024-25
COAL AND PETROLEUM 35
as a fuel in many industries situated
near the coal processing plants.
3.2 Petroleum
You know that petrol is used as a fuel in
light automobiles such as motor cycles/
scooters and cars. Heavy motor vehicles
like trucks and tractors run on diesel.
Petrol and diesel are obtained from a
natural resource called petroleum. The
word petroleum is derived from petra
(rock) and oleum (oil) as it is mined
from between the rocks under Earth as
shown in Fig. 3.4.
Do you know how petroleum is
formed?
Petroleum was formed from
organisms living in the sea. As these
organisms died, their bodies settled at
the bottom of the sea and got covered
with layers of sand and clay. Over
millions of years, absence of air, high
temperature and high pressure
Refining of Petroleum
Petroleum is a dark oily liquid. It has
an unpleasant odour. It is a mixture of
various constituents such as petroleum
gas, petrol, diesel, lubricating oil,
paraffin wax, etc. The process of
Fig. 3.4 : Petroleum and natural gas deposits
The world’s first oil well was drilled
in Pennsylvania, USA, in 1859. Eight
years later, in 1867, oil was struck
at Makum in Assam. In India, oil is
found in Assam, Gujarat, Mumbai
High and in the river basins of
Godavari and Krishna.
transformed the dead organisms into
petroleum and natural gas.
Look at Fig. 3.4. It shows the deposits
of petroleum and natural gas. You see
that the layer containing petroleum oil
and gas is above that of water. Why is it
so? Recall that oil and gas are lighter
than water and do not mix with it.
Wells
Gas
Oil
Water
Reservoir rock
Impervious
rock
2024-25
Page 5


COAL AND PETROLEUM
COAL AND PETROLEUM
Can air, water and soil be exhausted
by human activities? You have already
studied about water in Class VII. Is water
a limitless resource?
In the light of the availability of
various resources in nature, natural
resources can be broadly classified
into two kinds:
(i) Inexhaustible Natural Resources:
These resources are present in unlimited
quantity in nature and are not likely to
be exhausted by human activities.
Examples are: sunlight, air.
(ii) Exhaustible Natural Resources: The
amount of these resources in nature is
limited. They can be exhausted by
human activities. Examples of these
resources are forests, wildlife, minerals,
coal, petroleum, natural gas etc.
Activity 3.2
(It is a group activity)
Take some containers. Fill them
with  popcorn/peanuts/roasted
gram/toffees. Divide students into
groups of seven each. Further divide
each group into three subgroups
containing 1, 2 and 4 students.
Label them as first, second
and third generation respectively.
W
e use various materials for our
basic needs. Some of them are
found in nature and some
have been made by human efforts.
Activity 3.1
Make a list of various materials used
by us in daily life and classify them
as natural and man-made.
Natural Man-made
Can we use all our
natural resources
forever ?
Does this list include air, water, soil
and minerals? Since all these are
obtained from nature, they are called
natural resources.
2024-25
These sub-groups represent the
consumers. As population is
growing, second and third
generations have larger number of
consumers.
Put one full container for each
group on a table. Ask consumers of
the first generation from each group
to consume eatables from the
container of their group. Now, ask
the second generation consumers
from each group to do the same. Ask
students to observe carefully the
availability of eatables in each
container. If some thing is left in the
containers, ask third generation
from each group to consume it. Now,
finally observe whether all the
consumers of the third generation
got the eatables or not. Also observe
if anything is still left in any of the
containers.
Assume that the eatables in the
container represent the total
availability of an exhausible natural
resource like coal, petroleum or
natural gas. Each group may have a
different consumption pattern. Are
the earlier generations of any group
too greedy?  It may be that the earlier
generations in some groups were
concerned about the coming
generation(s) and left something for
them.
In this chapter we will learn about
some exhaustible natural resources
like coal, petroleum and natural gas.
These were formed from the dead
remains of living organisms (fossils).
So, these are all known as fossil
fuels.
3.1 Coal
You may have seen coal or heard about
it (Fig. 3.1). It is as hard as stone and is
black in colour.
Fig. 3.1: Coal
Coal is one of the fuels used to cook
food. Earlier, it was used in railway
engines to produce steam to run the
engine. It is also used in thermal power
plants to produce electricity. Coal is also
used as a fuel in various industries.
Story of Coal
Where do we get
coal from and how
is it formed?
About 300 million years ago the
earth had dense forests in low lying
wetland areas. Due to natural processes,
like flooding, these forests got buried
under the soil. As more soil deposited
over them, they were compressed. The
temperature also rose as they sank
deeper and deeper. Under high pressure
and high temperature, dead plants got
slowly converted to coal. As coal
contains mainly carbon, the slow
process of conversion of dead vegetation
into coal is called carbonisation. Since
it was formed from the remains of
vegetation, coal is also called a fossil fuel.
A coal mine is shown in Fig. 3.2.
COAL AND PETROLEUM 33
2024-25
SCIENCE 34
Fig. 3.2: A coal mine
Coal Gas
Coal gas is obtained during the
processing of coal to get coke. It is used
Coal gas was used for street lighting
for the first time in London in 1810
and in New York around 1820. Now a
days, it is used as a source of heat
rather than light.
These days, bitumen, a petroleum
product, is used in place of coal-tar
for metalling the roads.
Fig. 3.3: Coal tar
When heated in air, coal burns and
produces mainly carbon dioxide gas.
Coal is processed in industry to get
some useful products such as coke, coal
tar and coal gas.
Coke
It is a tough, porous and black
substance. It is an almost pure form of
carbon. Coke is used in the manufacture
of steel and in the extraction of many
metals.
Coal Tar
It is a black, thick liquid (Fig. 3.3) with
an unpleasant smell. It is a mixture of
about 200 substances. Products
obtained from coal tar are used as
starting materials for manufacturing
various substances used in everyday
life and in industry, like synthetic
dyes, drugs, explosives, perfumes,
plastics, paints, photographic materials,
roofing materials, etc. Interestingly,
naphthalene balls used to repel moths
and other insects are also obtained from
coal tar.
2024-25
COAL AND PETROLEUM 35
as a fuel in many industries situated
near the coal processing plants.
3.2 Petroleum
You know that petrol is used as a fuel in
light automobiles such as motor cycles/
scooters and cars. Heavy motor vehicles
like trucks and tractors run on diesel.
Petrol and diesel are obtained from a
natural resource called petroleum. The
word petroleum is derived from petra
(rock) and oleum (oil) as it is mined
from between the rocks under Earth as
shown in Fig. 3.4.
Do you know how petroleum is
formed?
Petroleum was formed from
organisms living in the sea. As these
organisms died, their bodies settled at
the bottom of the sea and got covered
with layers of sand and clay. Over
millions of years, absence of air, high
temperature and high pressure
Refining of Petroleum
Petroleum is a dark oily liquid. It has
an unpleasant odour. It is a mixture of
various constituents such as petroleum
gas, petrol, diesel, lubricating oil,
paraffin wax, etc. The process of
Fig. 3.4 : Petroleum and natural gas deposits
The world’s first oil well was drilled
in Pennsylvania, USA, in 1859. Eight
years later, in 1867, oil was struck
at Makum in Assam. In India, oil is
found in Assam, Gujarat, Mumbai
High and in the river basins of
Godavari and Krishna.
transformed the dead organisms into
petroleum and natural gas.
Look at Fig. 3.4. It shows the deposits
of petroleum and natural gas. You see
that the layer containing petroleum oil
and gas is above that of water. Why is it
so? Recall that oil and gas are lighter
than water and do not mix with it.
Wells
Gas
Oil
Water
Reservoir rock
Impervious
rock
2024-25
SCIENCE 36
separating the various constituents/
fractions of petroleum is known as
refining. It is carried out in a petroleum
refinery (Fig. 3.5).
Various constituents of petroleum
and their uses are given in Table 3.1.
Many useful substances are obtained
from petroleum and natural gas.
These are termed as ‘Petrochemicals’.
These are used in the manufacture
of detergents, fibres (polyester, nylon,
acrylic etc.), polythene and other
man-made plastics. Hydrogen gas
obtained from natural gas, is used in
the production of fertilisers (urea).
Due to its great commercial
importance, petroleum is also called
‘black gold’.
3.3 Natural Gas
Natural gas is a very important fossil
fuel because it is easy to transport
through pipes. Natural gas is stored
under high pressure as compressed
natural gas (CNG). CNG is used for
power generation. It is now being used
Table 3.1 Various Constituents of Petroleum and their Uses
S.No. Constituents of Petroleum                      Uses
1. Petroleum Gas in Liquid form Fuel for home and industry
(LPG)
2. Petrol Motor fuel, aviation fuel, solvent for
dry cleaning
3. Kerosene Fuel for stoves, lamps and for jet aircrafts
4. Diesel Fuel for heavy motor vehicles, electric
generators
5. Lubricating oil Lubrication
6. Paraffin wax Ointments, candles, vaseline etc.
7. Bitumen Paints, road surfacing
Fig. 3.5: A petroleum refinery
2024-25