Notes of chapter: Coal and Petroleum are presented below. Indepth notes along with worksheets and NCERT Solutions for Class 8.
(1)Natural resources-
The resources which we get from nature are called natural resources.
Eg:- Air, water, coal etc.
Types of natural resources –
Natural resources can be divided in two types on the basis of their availability.
(i)Inexhaustible natural resources-
The resources which are available in nature unlimited quantity and can not be exhausted or completely finished by human activities are called inexhaustible natural resources.
Eg:- Sunlight, air, water etc.
(ii)Exhaustible natural resources-
The resources which are available in nature in limited quantity and can be exhausted or completely finished by human activities are called exhaustible natural resources.
Eg:- Coal, petroleum, natural gas etc.
Exhaustible natural resources are called fossil fuels because these were formed from the dead remains of living organisms (Fossils).
(A) Coal-
The dense forest of low lying wetland areas got buried under the earth as a result of flood or natural activities. These forests were compressed by the more soil deposits over them and temperature also increases as these sank deeper and deeper. These dead plants converted to coal due to high pressure and high temperature. Therefore, coal is also called fossil fuel. The process of conversion of dead vegetation in to carbon is called carbonisation.
(a) Coal is hard like stone.
(b) It is black in colour.
Uses of coal-
(a) It is used in cooking, ironing.
(b) It was used in the steam railway engine to produce steam.
(c) It is used in thermal power plants to produce electricity.
(d) It is also used in many industries as a fuel.
(e)It is processed in industry to get some useful products such as coke, coal tar and coal gas.
Coke-
(a) It is a tough, porous and black substance.
(b) It is an almost pure form of carbon.
(c) It is used in the manufacture of steel and in the extraction of many metals.
Coal Tar-
(a) It is a black, thick liquid.
(b) It has unpleasant smell.
(c) It is a mixture of 200 substances.
Uses of coal tar-
(a) Products obtained from the coal tar are used in many things of everyday life as synthetic dyes, drugs, explosives, perfumes, plastic, paints etc.
(b)It is also used in naphthalene balls to repel moths and insects.
(c) It is also used in road making. Now a days, bitumen, a petroleum product is used in place of coal tar for metalling the roads.
Coal gas-
(a) It is obtained during the processing of coal to get coke.
Uses of coal gas-
(a) It is used as a fuel in many industries.
(b) Coal gas was first used for street lighting. Now , it is used as a source of heat rather than light.
(B) Petroleum-
Petroleum is formed from the dead organisms of sea. The bodies of these organisms settled at the bottom of sea. The layers of sand and clay covered these bodies. These bodies converted into the petroleum and natural gas in the presence of high pressure and high temperature and in the absence of air. The whole process took millions of year to complete.
(a) Petroleum is a dark oily liquid.
(b) It has an unpleasant odour.
(c) It is a mixture of various constituents as petroleum gas, petrol, diesel, lubricating oil, paraffin wax etc.
(d)The process of separating various constituents (petroleum gas, petrol, diesel, lubricating oil, paraffin wax etc.) of petroleum is known as refining. The place where whole process is take place is called petroleum refinery.
(e) It is found in Assam, Gujarat, Mumbai High and in the river basins of Godavari and Krishna.
Uses of petroleum-
(a) It is used in automobiles as a fuel.
(b) Petrochemicals are used in manufacturing of detergents, fibres as polyester, nylon etc., polythene etc.
Petroleum is also called ‘black gold” because of its commercial usefulness.
The substances which are obtained by the refining and processing of petroleum and natural gas is known as petrochemicals.
Various constituents of petroleum and their uses –
| SN. | Constituents of Petroleum | Uses |
| 1. | Liquified petroleum gas (LPG) | Fuel for home and industry |
| 2. | Petrol | Motor 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 | Ointment, candles, Vaseline etc. |
| 7. | Bitumen | Paints, road surfacing |
(C) Natural Gas-
Natural gas is a naturally occurring hydrogen gas mixture. Natural gas is obtained from under the earth or sea.
In India, it is found in Tripura, Rajasthan, Maharashtra and in the Krishna Godaveri delta.
Uses of Natural Gas-
(a) It is a very important fuel because it is easily transported through pipes to homes and factories where it can be used directly. CNG is used in many parts of India like Gujarat, Delhi, Ghaziabad, NoIda of Uttar Pradesh, Bombay etc. at home for cooking purposes.
(b) It is compressed under high pressure and used for power generation and as a fuel for vehicles as compressed natural gas (CNG). CNG is a cleaner fuel. Therefore no pollution occurs from its use.
(c) It is also used in fertilizer and chemicals manufacturing.
These coal and petroleum products are limited in nature because they need millions of years to convert dead organisms into fuel. The fuel obtained from exhaustible resource will be last for few hundreds year. It also causes air pollution. In India, the Petroleum Conservation Research Association (PCRA) advises people how to save patrol and diesel while driving. Their tips are discussed below:-
(a) Drive at a constant and moderate speed as far as possible.
(b) Switch off the engine at traffic lights or at a place where you have to wait.
(c) Ensure correct tyre pressure.
(d) Ensure regular maintenance of the vehicle.
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