CBSE NOTES Class 8 Science Chapter-Chapter 5. Coal and Petroleum Fossil Fuels

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Chapter 5. Coal and Petroleum

Useful Products of Caol: 

(A) Coke

(B) Coal Tar 

(C) Coal Gas 

(A) Coke : It is a tough, porous and black substance. It is almost pure form of
carbon.

Uses of Coke: 

(i) Coke is used in the manufactureof steel and in the extraction of many metals.

(ii) It works as reducing agent in the extraction of metals because it removes the oxygen from many metals oxides. 

(B) Coal tar: It is a black, thick liquid with unpleasant smell. It is a mixture of about 200 substances.

Uses of coal tar: 

(i) Products obtained from coal tar are used as starting materials for manufacturing
various substances used in everyday life and in industry, like synthetic dyes, drugs, explosives, perfumes, plastics, paints, photographic materials, roofing materials, etc. (ii) Interestingly, naphthalene balls used to repel moths and other insects are also obtained from coal tar.

(C) Coal Gas: Coal gas is obtained during the processing of coal to get coke.

Uses of coal gas: 

(i) It is used as a fuel in many industries situated near the coal processing plants.

Petroleum: petroleum is a natural resources which is chemically hydrocarbons yellowish-black liquid. Unrefined liquid is called crude oil. Under the refinary it give many petroleum products like petrol, diesel, kerosene, paraffin and other petroleum gases.

"Petrol and diesel are obtained from a natural resource called petroleum."

Name of some petroleum products: 

Petrol, diesel, kerosene, paraffin and other petroleum gases are petroleum products. 

Petroleum is called black gold: 

Petroleum gives so many useful and valuable products like petrol, diesel, kerosene, paraffin and other petroleum gases. Also many products called petrochemicals are obtained from petroleum like polythene, plastics and other polymers. These products are the base of many industries and have a number of commercial importance. Hence crude oil is black in colour but it is as valuable as gold. So people call it black gold. 

The advantage of using CNG and LPG:

(i) These are cleaner fuels .

(ii) These are low cost fuels.

(iii) These are available easily.

(iv) These can be used directly for burning in homes and factories where it can be supplied through pipes.

Full form of PCRA: 

PCRA is Petroleum Conservation Research Association

Full form of CNG : Compressed natural Gas

Full form of PNG : Petroleum Natural Gas

Full form of LPG : Liquid Petroleum Gas  

Formation of Petroleum: Petroleum is formed from organism living in the sea. When these organisms died, their bodies settle at the bottom of sea and got covered with layers of sand and clay. Over millions of years, they were transformed into petroleum, oil and natural gas under the absence of air and presence of high pressure.

The World's First Oil Well : The world’s first oil well was drilled in Pennsylvania, USA, in 1859. Eight years later, in 1867, oil was stuck at Makum in Assam. In India, oil is found in Assam, Gujarat, Mumbai High and in the river basins of Godavari and Krishna.  

Various Constituents of petroleum and their uses: 

Petroleum Refinery: The process of separating the various constituents/fractions of petroleum is known as refining. It is carried out in a petroleum refinery.

Natural Gas: Natural gas is a very important fossil fuel because it is easy to transport through pipes. Natural gas is stored under high pressure as compressed
natural gas (CNG).

Uses Of CNG:

(i) CNG is used for power generation.

(ii) It is now being used as a fuel for transport vehicles because it is less polluting.

(iii) Natural gas is also used as a starting material for the manufacture of a
number of chemicals and fertilisers.

Advantage of CNG: The great advantage of CNG is that it can be used directly for burning inhomes and factories where it can be supplied through pipes.

CNG Supply Network in India: A network of pipelines exists in Vadodara (Gujarat),
some parts of Delhi and other places.
Source of CNG In India: India has vast reserves of natural gas. In our country, natural gas has been found in Tripura, Rajasthan, Maharashtra and in the Krishna
Godavari delta.

Hazards of burning Fossil fuels: 

(i) Burning of fossil fuels is a major cause of air pollution.

(ii) It releases toxic gases in our environment like CO and CO₂ oxides of sulpher and nitrogen. 

(iii) Their use is also linked to global warming.

Petroleum Conservation Research Association (PCRA) advises people to save fuels: These tips are - 

(i) Drive at a constant and moderate speed as far as possible,
(ii) Switch off the engine at traffic lights or at a place where you have to wait,

(iii) Ensure correct tyre pressure, and
(iv) Ensure regular maintenance of the vehicle.