Quick Revision Notes & Formula Sheet

Class: 8th Science
Chapter: Coal and Petroleum
Board: MP Board

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### 1. Introduction to Resources

Resources are substances available in our environment that are used to satisfy our needs. They are broadly classified into two main types:

• Inexhaustible Natural Resources (अक्षय प्राकृतिक संसाधन): These resources are present in unlimited quantity in nature and are not likely to be exhausted by human activities.
  • Examples: Sunlight, Air.
• Exhaustible Natural Resources (समाप्य प्राकृतिक संसाधन): The amount of these resources in nature is limited. They can be exhausted by human activities.
  • Examples: Forests, wildlife, minerals, coal, and petroleum.

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### 2. Fossil Fuels (श्वाजी ईंधन / जीवाश्म ईंधन)

• Definition: Exhaustible natural resources formed from the dead remains of living organisms (plants and animals) millions of years ago are called fossil fuels.
• Examples: Coal, Petroleum, and Natural Gas.

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### 3. Coal (कोयला)

• What is it? As hard as stone and black in color.
• Uses: Used to cook food, in thermal power plants to produce electricity, and in various industries.
• Carbonisation (कार्बोनीकरण): The slow process of conversion of dead vegetation into coal under high temperature and high pressure over millions of years is called carbonisation.

Products of Coal Processing (कोयला के प्रक्रम से प्राप्त उत्पाद)

When coal is processed in industry, we get useful products:

1. Coke (कोक):
   • A tough, porous, and black substance.
   • Almost pure form of carbon.
   • Used in the manufacture of steel and in the extraction of many metals.
2. Coal Tar (कोलतार):
   • A black, thick liquid with an unpleasant smell.
   • A mixture of about 200 substances.
   • Used for manufacturing synthetic dyes, explosives, perfumes, plastics, paints, photographic materials, and naphthalene balls (used to repel moths and insects). Note: Bitumen (a petroleum product) is now used in place of coal-tar for metalling the roads.
3. Coal Gas (कोल गैस):
   • Obtained during the processing of coal to get coke.
   • Used as a source of fuel in many industries situated near the coal processing plants.

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### 4. Petroleum (पेट्रोलियम / कच्चा तेल)

• Etymology: Derived from petra (rock) and oleum (oil) because it is mined from between the rocks under the earth.
• Formation: Formed from organisms living in the sea. As these organisms died, their bodies settled at the bottom of the sea and got covered with layers of sand and clay. Over millions of years, absence of air, high temperature, and high pressure transformed the dead organisms into petroleum and natural gas.
• Refining of Petroleum (पेट्रोलियम का परिष्करण): Petroleum is a dark oily liquid. It is a mixture of various constituents such as petroleum gas, petrol, diesel, kerosene, paraffin wax, lubricating oil, etc. The process of separating the various constituents/fractions of petroleum is known as refining. It is carried out in a petroleum refinery.

Constituents of Petroleum and their Uses (पेट्रोलियम के घटक और उनके उपयोग):

1. Petroleum Gas in liquid form (LPG): Fuel for home and industry.
2. Petrol: Motor fuel, aviation fuel, solvent for dry cleaning.
3. Kerosene: Fuel for stoves, lamps, and for jet aircraft.
4. Diesel: Fuel for heavy motor vehicles, electric generators.
5. Lubricating Oil: Lubrication.
6. Paraffin Wax: Ointments, candles, vaseline, etc.
7. Bitumen: Paints, road surfacing.

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### 5. Natural Gas (प्राकृतिक गैस)

• Importance: Very important fossil fuel because it is easy to transport through pipes.
• Storage: Stored under high pressure as Compressed Natural Gas (CNG).
• Uses:
  • Power generation.
  • Used as fuel for transport vehicles because it is less polluting (eco-friendly).
  • Used as a starting material for the manufacture of a number of chemicals and fertilizers.
• Indian Reserves: In India, natural gas has been found in Tripura, Rajasthan, Maharashtra, and in the Krishna-Godavari delta.

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### 6. Conserve Resources: PCRA Guidelines

Since coal and petroleum are exhaustible and their burning causes air pollution and contributes to global warming, we need to use them wisely.

The PCRA (Petroleum Conservation Research Association) in India advises people how to save petrol/diesel while driving:

1. Drive at a constant and moderate speed as far as possible.
2. Switch off the engine at traffic lights or at a place where you have to wait.
3. Ensure correct tyre pressure.
4. Ensure regular maintenance of the vehicle.