Coal and Petroleum Notes for Class 8, Ideal for CBSE based on NCERT

Important topics covered in Coal and petroleum notes:

• Introduction
• Natural Resources
• Inexhaustible Natural Resources
• Exhaustible Natural resources
• Coal
• Petroleum
• Natural Gas
• Limited Natural Resources

---

Introduction:

• In our day to day life, we use various materials to fulfil our needs.
• Some of them are naturals while others are artificial/man-made resources.
• Some example of natural resources are:

Natural Resources	Man-made Resources
Silk	Clothes
Wood	Paper
Leather	Shoes
Rubber	Tyre
Fur	Pillow
Fabrics	Suit

Natural Resources:

• The resources which are present in nature and is used by living organisms in various ways are called natural resources.
• These resources can be exploited for economic gain.
• The raw material for the food we eat, the clothes we wear is obtained from natural resources.

Types of natural resources:

There are two types of natural resources. They are:

1. Inexhaustible resources
2. Exhaustible resources

Inexhaustible resources:

• The resources which are never-ending and will not be depleted even after continuous usage are inexhaustible resources.
• These resources are available in large quantities in air.
• Sunlight and air are some examples.

Exhaustible resources:

• The resources which are present in a limited amount and can be depleted after continuous usage are said to be exhaustible resources.
• Overexploitation of exhaustible resources can lead to a higher rate of depletion.
• Coal, petroleum and minerals are some examples of exhaustible resources.

Fossil fuels

• Dead and decayed remains of organisms which are more than 10,000 years old are called fossils.
• Those substances which bums in air to produce energy without releasing harmful gases in large quantities are said to be fuels.
• The formation of coal and petroleum possess the same reason. So these are said to be fossil fuels.

Calorific value of fuels:

• The amount of heat liberated by complete burning of a unit mass or volume of fuel is said to be calorific value of the fuel.
• To find out the calorific value of liquid or gaseous fuels, volume of fuel is considered while for solid fuels mass of fuel is considered.
• Its unit is KJ/Kg.
• Calorific value = \(\frac{Amount\:of \:liberated\: heat\: energy}{Total\:mass\:of\:fuel}\)

Features of ideal fuel:

• Possess high calorific values.
• Pollution free by not releasing any harmful gases
• Cost-effective
• Easily available
• Easy to handle and transport and store.
• Moderate ignition temperature
• Rate of combustion should also be moderate.

Coal

• It is quite hard and stone-like substance.
• Coal appears black in colour.
• It is of great use since times.
• We use coal to heat a substance, cook food, run trains, in thermal power plants to produce electricity etc.

History of coal:

• Millions of years ago on the earth there were only forest and grasslands.
• Due to natural calamities, like floods, earthquakes the forests are buried under the soil.
• Above the dead plants, layers of soil were formed.
• As dead plants went deeper and deeper under the soil they got compressed.
• The excess temperature and pressure produced on these materials converted it into coal.

Carbonisation

• The process of conversion of dead plants vegetation into coal is said to be carbonization.
• Coal is mainly composed of carbon as on burning it releases carbon and its product.

Uses of coal

• Earlier it was used as fuel in steam engine.
• Thermal power plants use coal as fuel.
• Some households, dhabas still uses coal as the kitchen fuel.

Products of coal:

Some of the widely used products of coal are:

Coke:

• Coke is the form of coal which is hard, porous and black in colour.
• It is said to be the purest form of carbon.
• It is used in extraction of metals and manufacturing of steel.

Coal Tar:

• It is thick black liquid.
• It bears unpleasant smell.
• It is mixture of different substances.
• Synthetic dyes, explosives, drugs, perfumes, plastics, paints, roofing materials, etc. are prepared from Coal tar.
• Naphthalene balls for keeping insects away are also made from Coal tar.
• A form of coal tar i.e. bitumen is used for metalling of roads.

Coal Gas:

• Coal gas is mid material obtained between the process of obtaining coke from coal.
• It is used as fuel in many industries which are situated near coal mines.
• Earlier coal gas was used in London for lightning process but now it is used for heating purpose rather than lightning process.

Petroleum:

• Petroleum is a dark oily liquid.
• It is a mixture of various substances, like petroleum gas, diesel, petrol, paraffin wax, lubricating oil, etc.
• Earlier several organisms lived in sea.
• When they died their remains got settled at the bottom of the sea.
• The layers of clay deposited over it.
• In the absence of air with excess of temperature and pressure converted them to petroleum.

Refining of petroleum:

• The process of separating its constituents (petrol, diesel, wax etc.) from petroleum is said to be refining.
• Refining is done in petroleum refinery.
• Petrochemicals are useful substances are obtained from petroleum and natural gas.
• Detergents, polythene, fibres (nylon, polyester, acrylic etc.) and other artificial plastics are manufactured from petrochemicals.
• Due to the great commercial importance of petroleum, these are termed as “black gold”.

Uses of petroleum and its constituents:

The uses of different constituent of petroleum are listed below;

• Liquid Petroleum Gas (LPG): It is the main source of fuel in household and in some industries.
• Petrol: Automobiles uses it as a fuel and also used in dry cleaning.
• Diesel: It is used as a fuel for heavy machinery like rail engine, factories machines etc.
• Kerosene: It is mainly used in lamps and for jet aircraft.
• Paraffin wax: It is used in ointments, candles, cosmetics, Vaseline etc.
• Lubricating oil: For lubricating machinery lubricating oil is used.
• Bitumen: Used in metalling roads.

Natural gas:

• Millions of years ago natural gas was formed.
• Microscopic sea plants and animals died & got buried under the mud.
• Under anaerobic conditions, these plants and animals changed to natural gas.
• Natural gas mainly contains methane with 85% composition.
• 10% of it is ethane and 3% butane is present in it.
• When Natural Gas is compressed at high pressure then gets converted into compressed natural gases.
• It is ideal fuel with a calorific value of 55Ktj/g.

Uses of Natural gas:

• It is also used for power generation.
• Because of its less pollution measure, it is used in vehicle as fuel.
• It can easily be transported from one place to another through pipeline.
• It is also used as the beginning material for manufacturing of fertilizers.

Conservation of natural resources:

• It took millions of years for the dead organisms to get converted into coal, petroleum or natural gas.
• We have limited known resources.
• These resources are exhaustible.
• It is our responsibility to use them as less as possible.
• To fulfil our energy requirement, we must look for alternative sources of energy such as solar energy, tidal energy, wind energy, etc.
• Limited usage of these resources will save our earth from pollution, which will decrease the risk of Global warming.