Coal and Petroleum Class 8 Notes Science Chapter 3

Facts that Matter

• Natural Resources: The various resources which are obtained from the nature are called natural resources. For example; air, water and soil etc.
• Types of natural resources:
  • Exhaustible resources
  • Inexhaustible resources
• Exhaustible Natural Resources: The resources which are limited in the nature and can be exhausted very soon by human activities are called exhaustible natural resources.

For example; forests, coal, petroleum, minerals, wildlife and natural gas.

• Inexhaustible Natural Resources: The resources which are present in unlimited quantity in nature and are not likely to be exhausted by human activities are called inexhaustible natural resources. For example, air and sunlight.
• Fossils: The remains of dead plants and animals, which are buried under the rocks millions of years ago, are called fossils.
• Fossil Fuels: The fuels formed by the remains of dead plants and animals are called fossil fuels.
• Coal: It is a fossil fuel formed by deeply buried remains of vegetation under compression, high pressure and high temperature over millions of years.
• Carbonisation: A s coal contains mainly carbon, the slow process of conversion of dead vegetation into coal is called carbonisation.
• Coke: It is a tough, porous and black substance obtained from coal. It is an almost pure form of carbon.
• Destructive Distillation: The process of heating of wood or coal in the absence of air is called destructive distillation.
• Coal Gas: It is a gas obtained during the processing of coal to get coke. It can be used as a source of light and heat.
• Coal tar. It is a black, thick liquid obtained as the product during the processing of coal to get coke. It is a mixture of 200 substances. Its many products are used as starting materials for manufacturing a large number of substances such as dyes, drugs, perfumes, naphthalene balls. Coal tar was also used for metalling the road (nowadays, a petroleum product bitumen is used for metalling the roads).
• Petroleum. It is a dark oily liquid from which many valuable substances, like petrol and diesel are obtained. Over millions of years under high temperature and high pressure transformed dead sea organisms into petroleum and natural gas.
• Natural Gas. It is a very important fossil fuel. Natural gas is stored under high pressure as compressed natural gas (CNG). CNG is very less polluting and cheaper fuel.
• Refining of Petroleum: The process of separating the various constituents/fractions of petroleum is called refining. It is carried out in a petroleum refinery.
• Constituents of Petroleum: There are various substances separated in refining of petroleum. They are: LPG (Liquefied Petroleum Gas), petrol, kerosene, diesel, lubricating oil, paraffin wax and bitumen.
• Bitumen: It is the petroleum product which is now used in the road surfacing in place of coal tar.
• Black Gold: Due to great commercial importance of petroleum, it is also known as ‘black gold’.
• Petrochemicals: The useful substances that are obtained from petroleum and natural gas are called as petrochemicals.