Notes of the Chapter - Coal & Petroleum, Class 8, Science PDF Download

Coal and Petroleum

Natural Resources:

There are two types of natural resources:

Inexhaustible Natural Resources and Exhaustible Natural Resource

Inexhaustible Natural Resources: Resources which do not exhaust and which are available in plenty in nature are known as inexhaustible natural resources. For example – air, sunlight, etc.

Exhaustible Natural Resources: Resources which get exhausted and are not available in nature in plenty and are known as exhaustible natural resources. They take longer to get replenished. For example – coal, petroleum, forest, minerals, etc.

Coal and Petroleum: Coal and petroleum are exhaustible natural resources as their availability is limited in nature. Coal and petroleum are used mainly as fuel. Coal is used as fuel, petroleum products are used to run vehicle and for many other purposes. Coal and petroleum are known as fossil fuels since they are formed from remains of living organism.

Coal

Coal is a black coloured stone-like material. Coal is used to produce electricity in thermal power stations. Coal was used to run steam engine till recent years in India. Coal gives carbon dioxide when burnt in air.

Formation of Coal

About 300 millions year ago, dense forest in low lying lands of earth got buried because of many natural processes. In the due course, they sank deeper and deeper. Inside the earth, because of high pressure and temperature they slowly converted into coal. Such slow process of conversion of dead vegetation into coal is called carbonization.

Coal is considered as fossil fuel as it is formed because of carbonization of dead remains of living organism.

Coal is mined from earth and processed to obtain many useful products, such as coal, coke, coal tar, etc.

Coke

Coke is almost pure form of carbon. Coke is a porous, black and similar to coal. Coke has high percentage of carbon and very low percent of impurities. It is obtained from destructive distillation of a particular type of coal. Coke is used as fuel, as reducing agent in the smelting of iron ore in blast furnace. It is used in the manufacturing of steel and in the extraction of many types of metals.

Coal Tar : -

Coal tar is obtained as one of the by-products while obtaining the coke or coal gas. Coal tar is a highly viscous liquid and brown-black in colour. It is a variable mixture of many substances.

Coal tar is used in the manufacturing of many products; such as synthetic dyes, drugs, explosive, perfumes, plastics, roofing material, etc. as starting material.

Till about two decades ago, coal tar was used as binding material in the making of roads. Now-a-days bitumen is used in making of roads in the place of coal tar.

Coal gas

Coal gas is also one of the by-products in the processing of coke. Coal gas is used as fuel mainly for heating in many industries.

Petroleum

The word petroleum is used for both naturally occurring crude oil and other petroleum products which are obtained after refining of crude oil, such as petrol, diesel, etc. Petrol and diesel are highly consumed fuel today as these are used to run vehicles.

Petroleum is a dark oily liquid having unpleasant odour.

Formation of Petroleum

Petroleum is formed from the dead remains of living organisms which lived in sea and were buried millions of year ago below the sea bed. Because of high pressure and temperature those dead remains were transformed into petroleum. Since, petroleum is the product of dead remains, so it is known as fossil fuel.

Extraction of petroleum

Petroleum is extracted from the reservoir usually found in sea beds and river basin by drilling through pipe lines. Such places where reservoir of petroleum are found and extracted out by drilling are known as oil well.

Refining of Petroleum

After extraction, petroleum is refined to obtain petrol, diesel, lubricating oil, wax, paraffin, bitumen, kerosene, etc. Place where refining process of petroleum is done is called petroleum refinery.

Natural Gas

Natural gas is naturally occurring hydrocarbon gas. Natural gas is a mixture of methane, higher alkanes, carbon dioxide, etc. Natural gas is found in deep underground rock formation as fossil fuel. It is one of the most important fuel.

Natural gas can be transported through pipeline and can be compressed to smaller volume. Compressed natural gas (CNG) is used for running vehicle. Natural gas can be used directly for burning as fuel. It is a clean fuel as it creates least pollution.

Natural gas is used as starting material in many industries, such as fertilizer and chemical.

In India natural gas reserves are found in Tripura, Rajasthan, Maharashtra, and Krishna and Godavari delta.

Some Natural Resources are Limited

Petroleum, coal, natural gas, etc. are natural resources but available in limited amount. Thus, it is necessary to use them with care.

Some steps to conserve fossil fuels (Natural Resources):

• Switch off the engine of vehicle when waiting on signals or at other places.
• Drive the vehicle with constant and moderate speed.
• Maintain the correct tyre pressure for low consumption of fuel.
• Maintain the vehicle by regular checking to ensure less consumption of fuel.