Coal and Petroleum Class 8 Notes - Chapter 5

Introduction to Coal and Petroleum


Energy can be extracted from natural resources in many forms, and it can be transferred from one body to another in form of heat or work.

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Types of Energy

Some different types of energies are:

  • Mechanical energy
  • Chemical energy
  • Thermal energy
  • Nuclear energy
  • Solar energy
  • Wind energy
  • Sound energy
  • Electrical energy

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Energy Conversion from One Form to Another

  • Energy can neither be created nor be destroyed but it can be transformed from one form to another.
  • Eg: In Microphone: Sound energy is converted to electrical energy.

Natural Resources

Natural resources are the resources that are provided by the earth. Two types:

  • Inexhaustible/Renewable natural resources are present in unlimited quantity in nature. Eg: Sunlight, wind.
  • Exhaustible/Non-Renewable natural resources are present in limited quantity in nature. Eg: Coal, petroleum.

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Fossil Fuels

Fossil fuels are the exhaustible resources that are formed from the decomposition of dead organic matter. Eg: Coal, Natural gas

For More Information On History of Fuel, Watch The Below Video:

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Energy Stored in Fossil Fuels

Energy stored in fossil fuels are derived from decayed animals and plants that exist for millions of years.

Energy Utilisation from Fossil Fuels

  • 40% energy used by the industries
  • 24% energy used by the Transportation sector
  • 6% energy used by farms
  • 30% energy used for domestic and other purposes.

Coal Formation


Coal is a black coloured fossil fuel, which is extracted from the ground and is used as a fuel for different purposes.


Peat is a dark fibrous fuel composes of partly decomposed plant matter. It is the first stage in the formation of coal.

Formation of Coal

Under high pressure and temperature, the dead vegetation gets converted into coal. This process is called as carbonisation.
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For More Information On How Coal is Formed? Watch The Below Video:

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Types of Coal

Types of Coal

There are 4 types of coals:

  • Anthracite
  • Bituminous
  • Sub-bituminous
  • Lignite

Destructive Distillation of Coal

Destructive distillation of coal is the process of heating of coal in the absence of air. By-products formed in this process are coke, coal tar, ammonia, coal gas.
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For More Information On Destructive Distillation Of Coal, Watch The Below Video:

Coal Tar

Coal tar is a black thick liquid with an unpleasant smell and used as a starting material for manufacturing various substances.

Coal Gas

Coal gas is a fuel produced during the destructive distillation of coal. It is used as a fuel in many industries.

Ammonia Liquor

Ammonia liquor or ammonium hydroxide is one of the by-products formed during the destructive distillation of coal. It is used to make fertilizers.


Coke is a black coloured substance and pure form of carbon used for manufacturing steel and extraction of metals.

Extraction of Oil

Oil Wells and Reservoirs

  • An oil well is used to bring the oil or other hydrocarbons to the surface. It is a long hole created into the earth.
  • An oil reservoir is the underground lake of oil composed of hydrocarbons.

Extraction of Oils

Extraction of oil is the process by which usable oil is extracted from the earth’s surface location.

Determining the Characteristics of Oil Reservoirs

Characteristics of oil reservoir are:

  • Devices like geophones are used to determine the presence of oil in rocks by identifying the reflected sound waves.
  • Exploratory wells are used to extract oil samples.

Primary Production of Oil

The natural flow of oil is called as the primary production of the oil. It can persist for days or years.

Secondary Recovery Process

The secondary process can be carried out by the process of:

  • water flooding
  • injecting chemicals into the reservoir.
  • injecting carbon dioxide into the reservoir.
  • microbially enhanced oil recovery

Fractional Distillation

Crude Oil

Crude oil is a type of fossil fuel, which is an unrefined petroleum product composed of hydrocarbons.

For More Information On How Crude Oil is Processed? Watch The Below Video:

Boiling Point and Vaporisation

  • The boiling point is the temperature when the pressure exerted by surroundings on liquid & pressure of liquid becomes equal.
  • Vaporisation is the process of changing the state from liquid to gas.

Oil Refining or Fractional Distillation

Oil refining or fractional distillation is the process of separating liquids with different boiling points at different temperatures using fractional columns.

Uses of Products Obtained in Fractional Distillation

Products and its uses:

  • LPG: Fuel for home and industry
  • Petrol and diesel: Motor and aviation fuel
  • Kerosene: Fuel for stoves and lamps
  • Lubricating oil: Lubrication
  • Bitumen: Used to make paints
  • Paraffin wax: Used to make ointments, candles

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Shortage of Petroleum and Tips for Its Conservation

  • Petroleum should be carefully used to avoid its shortage.
  • PCRA proposed some methods to save petrol and diesel like driving vehicles at constant speed.

Natural Gas

Hazards and Estimates of Fossil Fuels

Hazards caused due to excessive use of fossil fuels:

  • Air pollution
  • Global warming

Estimates of fossil fuel:

  • Coal may persist for another century and petroleum for another 40 years.

For More Information On Effect of Burning Fuels on the Environment, Watch The Below Video:

Natural Gas

Natural gas is a colourless, odourless fossil fuel, which is transported through pipes from one place to another.

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CNG and Its Advantages

Natural gas stored under high pressure is known as CNG.
Advantages of CNG are:

  • It’s a Cleaner fuel
  • It’s less polluting
  • It can be used directly for burning.

Occurrences of Natural Gas in India

Natural gas are found in parts of Tripura, Rajasthan, Maharashtra, Tamilnadu, Andhra Pradesh.

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Also Read

Frequently asked Questions on CBSE Class 8 Science Notes Chapter 5: Coal and Petroleum

What is fossil fuel?

A fossil fuel is a hydrocarbon-containing material formed underground from the remains of dead plants and animals that humans extract and burn to release energy for use.

What are the types of fossil fuels?

1. Petroleum 2. Coal 3. Natural gas 4. Orimulsion

What are the uses of ‘Fractional distillation’?

1. Component separation into different phases 2. Purification of organic compounds

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