Best NCERT Class 8 Chapter 5 Coal and Petroleum Notes

Coal and Petroleum Class 8 Notes


Like various other materials found in nature, Coal and Petroleum are also important assets found in nature that fulfill human needs. Let us now see the topics to be discussed in this Coal and Petroleum class 8 notes.

To be discussed:

  • Natural Resources and their types
  • How Coal was Formed
  • Products of Coal
  • Formation of Petroleum
  • Refining of Petroleum
  • Various Petroleum products and their Uses
  • Natural Gas

Natural Resources

Define Natural resources.

Natural Resources are the materials found in nature that fulfill human needs.

Types of Natural Resources

  • Exhaustible Resources
  • Inexhaustible Resources

Define Exhaustible and Inexhaustible Resources?

Exhaustible resources are the natural resources that are limited in quantity and can run out if we do not use them wisely. These resources are not replenished quickly.

Example: Fossil Fuels like coal and petroleum and minerals such as gold, silver, iron etc

Inexhaustible Resources are the natural resources that are available in unlimited quantity and won’t run out.

Example: Solar Energy, Wind Energy, etc.


It is a black color solid hard substance used for domestic and commercial purposes. Like Petroleum, it is also a very important fossil fuel.

Coal mining is the process of extracting coal from the earth’s crust.

Coal is of different types based on carbon content, moisture, and impurities. The higher the amount of carbon content, the better the quality of coal. Anthracite, Bituminous, Lignite, and Peat are some important common types.

Coal Formation

The formation of Coal took place over millions of years. Long before when there were long grasses and trees, they fell and were trapped in the low-lying swampy areas. With the passage of time, they got buried and covered with soil. These got compressed as more soil was deposited over them. As they went deeper and deeper, it increases the pressure and the temperature. Hence, these dead plants got slowly converted to coal.

Define Carbonization

Carbonization: the slow process of conversion of dead vegetation into coal is called carbonization. (NCERT Definition)

Products of Coal

There are many useful products of coal when coal is treated in industries. Some of the important products of coal are mentioned below-

  • Coke is a tough, porous, and black substance, and is an almost pure form of carbon.
  • Coke is used in the manufacture of steel
  • It is also used in the extraction of many metals.
Coal Tar
  • black, thick liquid with an unpleasant smell.
  • It is composed of about 200 substances.
  • used to make naphthalene balls
  • used in manufacturing materials used in everyday life and in the industry such as dyes, drugs, plastics, etc.
Coal Gas

It is a by-product when coal is processed to make coke. It is used as a heating source. Earlier Coal gas was used for lighting purposes.


It is a dark-colored mixture of various substances- hydrocarbons, and unwanted impurities.

  • It is a combination of two words Petra which means Rock and Oleum means Oil, so it is called rock oil.
  • It is also called crude oil or mineral oil.

The Largest Reservoirs of Petroleum are- Venezuela, Saudi Arabia, Irag, Iran

Define Petrochemicals

The useful substances that are obtained from petroleum and natural gas are called Petrochemicals.

Petroleum Formation

How Petroleum is formed?

Petroleum is formed from the marine organisms which died and settled at the bottom of the sea. As time passed (millions of years), they got covered with sand and clay causing high pressure. Due to high pressure and also temperature and absence of air, these dead organisms also called fossils got converted into petroleum oil and natural gas.

Petroleum Refining

How is Refining of Petroleum done?

It is the process of conversion of crude oil into useful products called petroleum refining.

The refining of Petroleum can be done in the following steps-

  1. Extraction of Crude Oil
  2. Separation of Water and Sulphur (Copper Oxide)
  3. Refining of Petroleum

The process of refining is done in a petroleum refinery by the method of fractional distillation.

Define Fractional Distillation.

Fractional Distillation– a technique of separating miscible liquids that differ in boiling points.

Fractional Distillation
Fractional Distillation of Crude Oil

In this method, after the separation of water and sulphur the crude oil is passed through a furnace (heated up to 400°C). The vapors formed are passed through a long cylindrical shape body called a fractional column with horizontal SS trays. This fractional column has openings beside the trays at different temperatures. The various constituents are collected when they reach their boiling points.

Various Petroleum Products and their Uses

Some of the important Petroleum products and their usage are-

  1. LPG- Fuel for home and industry
  2. Gasoline or Petrol- Motor fuel, aviation fuel, dry cleaning solvent
  3. Diesel- heavy vehicles’ Fuel, electric generators
  4. Kerosene- Fuel for stoves, lamps, and for jet aircraft
  5. Lubricating Oil- Lubrication
  6. Paraffin Wax- Ointments, Vaseline
  7. Bitumen- Paints, road surfacing

Natural Gas

Natural gas is formed along with petroleum. Natural Gas needs high temperature and pressure.

  • The higher the temperature and pressure the higher will be the natural gas compared to petroleum.


It is an acronym for Compressed Natural Gas. Natural gas when kept or compressed at high pressure is called CNG.

It is environmentally friendly, i.e., it doesn’t cause pollution. It is used in vehicles and power generation.

Natural Gas Reservoir

In India, the Natural Gas Reservoirs are found in Tripura, Rajasthan, Maharashtra, and in the Krishna Godavari delta.

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