Coal and Petroleum

We use different materials for our basic needs. Some of these come from nature, and some are man-made. Examples of natural resources: Air, water, soil, minerals, forests, coal, petroleum, natural gas. Examples of man-made resources: Plastic, glass, cement, steel, paper, clothes.

Two kinds of natural resources

1. Inexhaustible Natural Resources
   
   

   • These resources are always available in unlimited amounts.
     
     

   • They cannot be exhausted by human activities.
     
     

   • Examples: Sunlight, air, wind, tides.
     
     

2. Exhaustible Natural Resources
   
   

   • These resources are limited and can be exhausted if used excessively.
     
     

   • Examples: Coal, petroleum, natural gas, forests, wildlife, minerals.
     
     

Important point: Air, water, soil, and minerals are natural resources, but water and soil can get polluted or overused. Therefore, not all natural resources are limitless.

Coal (Section 5.1)

What is coal?

• Coal is a hard, black substance, almost as hard as stone.
  
  

• It is mainly used as a fuel for cooking, running engines, and generating electricity in thermal power plants.
  
  

Uses of coal

• Old railway engines used coal to produce steam to run the engine.
  
  

• Coal is used as fuel in thermal power plants to generate electricity.
  
  

• Many industries use coal as a fuel in their manufacturing processes.
  
  

• Coal was also used for cooking food before modern fuels became common.
  
  

Formation of coal

• About 300 million years ago, the Earth had dense forests in low-lying wet areas.
  
  

• Natural events like floods buried these forests under layers of soil.
  
  

• Over millions of years, more soil layers deposited on top, and the buried plants were subjected to high pressure and high temperature.
  
  

• This caused dead plants to slowly change into coal, a process called carbonisation.
  
  

• Because coal is formed from dead plants over millions of years, it is called a fossil fuel.
  
  

Carbonisation: The slow process by which dead vegetation is transformed into coal due to heat and pressure over millions of years.

What happens when coal burns?

• When heated in air, coal burns and produces mainly carbon dioxide gas.

• This burning releases energy used for cooking, heating, or running machines.

Products of Coal

When coal is processed in industries, it produces several useful products:

1. Coke
   
   

   • Tough, porous, and black in color.
     
     

   • Almost pure carbon.
     
     

   • Used in steel manufacturing and metal extraction.
     
     

2. Coal Tar
   
   

   • Black, thick liquid with a strong smell.
     
     

   • Contains a mixture of about 200 substances.
     
     

   • Used to produce synthetic dyes, drugs, explosives, perfumes, plastics, paints, photographic chemicals, and roofing materials.
     
     

   • Naphthalene balls (used as moth repellents) are also made from coal tar.
     
     

   • Today, bitumen (a petroleum product) is often used instead of coal tar for road construction.
     
     

3. Coal Gas
   
   

   • Obtained during the process of making coke.
     
     

   • Used as fuel in industries located near coal processing plants.
     
     

   • Historically used for street lighting in early 1800s London and New York.
     
     

   • Now mainly used as a source of heat.

Petroleum (Section 5.2)

What is petroleum?

• Petroleum is a dark, oily liquid with an unpleasant odor.
  
  

• It is a mixture of many different substances.
  
  

Formation of petroleum

• Millions of years ago, tiny plants and animals lived in the sea.
  
  

• When they died, their bodies sank to the bottom and were covered by sand and clay.
  
  

• Over time, in the absence of air, and under high temperature and pressure, their remains changed into petroleum and natural gas.
  
  

Where petroleum is found

• Petroleum and natural gas are trapped in layers of impervious rock above water.
  
  

• Oil and gas are lighter than water and do not mix with it.
  
  

History of petroleum

• The world’s first oil well was drilled in Pennsylvania, USA, in 1859.
  
  

• In India, oil was first found in Makum, Assam, in 1867.
  
  

• Currently, petroleum is found in Assam, Gujarat, Mumbai High, and the Godavari and Krishna river basins.

Refining of Petroleum

What is refining?

• Refining is the process of separating petroleum into its useful parts (fractions).
  
  

• This is done in a petroleum refinery.

Major products of petroleum and their uses

Petroleum gas (LPG) - Fuel for homes and industry

Petrol - Motor fuel, aviation fuel, dry-cleaning solvent

Diesel - Fuel for heavy vehicles and generators

Kerosene - Fuel for stoves, lamps, and jet aircraft

Lubricating oil - Reduces friction in machines

Paraffin wax - Candles, ointments, Vaseline

Bitumen - Paints, road surfacing

Petrochemicals

• Chemicals obtained from petroleum and natural gas are called petrochemicals.
  
  

• Used to make detergents, synthetic fibres (nylon, polyester, acrylic), polythene, and plastics.
  
  

• Hydrogen from natural gas is used to produce fertilizers like urea.
  
  

• Because petroleum is so important commercially, it is called black gold.

Natural Gas (Section 5.3)

• Natural gas is a fossil fuel that can easily be transported through pipes.
  
  

• It can be stored under high pressure as Compressed Natural Gas (CNG).

Uses of natural gas

• Power generation.
  
  

• Fuel for vehicles (CNG is less polluting than petrol or diesel).
  
  

• Supplied directly to homes and factories through pipelines for cooking and heating.
  
  

• Used as a raw material to make chemicals and fertilizers.

Where found in India

• Tripura, Rajasthan, Maharashtra, Krishna–Godavari delta.

Important note

• Coal, petroleum, and natural gas cannot be prepared in the laboratory because they take millions of years to form under natural conditions.

Conservation of Fossil Fuels

• Coal, petroleum, and natural gas are exhaustible resources.
  
  

• If used carelessly, these fuels may finish in a few hundred years.
  
  

• Burning fossil fuels causes air pollution and contributes to global warming.
  
  

• We should use these fuels judiciously to protect the environment and make them last longer.

Tips from PCRA (Petroleum Conservation Research Association)

1. Drive at a steady and moderate speed.
   
   

2. Switch off the engine while waiting at traffic lights or long stops.
   
   

3. Keep the correct tyre pressure.
   
   

4. Perform regular vehicle maintenance.
   
   

Quick Revision Points

• Coal, petroleum, and natural gas are fossil fuels.
  
  

• Fossil fuels were formed from dead plants and animals millions of years ago.
  
  

• Products of coal: coke, coal tar, coal gas.
  
  

• Products of petroleum: petroleum gas, petrol, diesel, kerosene, lubricating oil, paraffin wax, bitumen.
  
  

• Petrochemicals are obtained from petroleum and natural gas.
  
  

Fossil fuels are limited; their use must be careful and responsible. 

Difficult/New Words with Pronunciation and Meaning 

1. Fossil Fuel (FAW-sil fyool) - Fuels formed from the remains of dead plants and animals buried millions of years ago.
   Examples: Coal, petroleum, and natural gas are fossil fuels.
   
   

2. Exhaustible (eg-ZAW-stuh-bul) - A resource that can get used up completely if we are not careful.
   Example: Coal is an exhaustible resource.
   
   

3. Inexhaustible (in-ig-ZAW-stuh-bul) - A resource that will never finish, no matter how much we use.
   Example: Sunlight and air are inexhaustible resources.
   
   

4. Carbonisation (kar-buh-nuh-ZAY-shun) - Conversion of dead plants into coal over millions of years.
   Example: Carbonisation turned the buried plants into coal.
   
   

5. Coal (kohl) - A hard, black fuel formed from dead plants.
   Example: Coal is used in thermal power plants.
   
   

6. Coke (kohk) - Hard, porous, almost pure carbon made from coal.
   Example: Coke is used in steel factories.
   
   

7. Coal Tar (kohl tahr) - Thick, black liquid obtained from coal processing.
   Example: Coal tar is used to make dyes and medicines.
   
   

8. Porous (POR-uhs) - Having tiny holes that allow air or water to pass through.
   Example: Coke is porous.
   
   

9. Refining / Refinery (ri-FY-ning / ri-FY-nuh-ree) - Refining = separating petroleum into useful parts.
   Refinery = a factory where refining is done.
   Example: Petrol is made in a petroleum refinery.
   
   

10. Paraffin Wax (PAIR-uh-fin) - A wax obtained from petroleum used in candles and ointments.
    Example: Paraffin wax is used in making candles.
    
    

11. Bitumen (BIT-uh-men) - Sticky black substance from petroleum used for roads and roofing.
    Example: Roads are covered with hot bitumen.
    
    

12. Petrochemicals (pet-ro-CHEM-i-kuls) - Chemicals made from petroleum or natural gas to produce plastics, fibres, detergents, etc.
    Example: Many plastics are made from petrochemicals.
    
    

13. Compressed Natural Gas (CNG) - Natural gas stored under high pressure, used for vehicles and power generation.
    Example: Many buses in cities run on CNG.
    
    

14. LPG (ell-pee-gee) -  Liquefied petroleum gas used for cooking and industry.
    Example: LPG is commonly used in kitchens.
    
    

15. Impervious (im-PUR-vee-us) - Not letting liquids pass through.
    Example: Impervious rock traps oil and gas underground.
    
    

16. Deposit / Deposited (di-PAZ-it / di-PAZ-it-ed) - Material that is laid down in layers.
    Example: Dead organisms were deposited under sand and clay.
    
    

17. Viscous (VISS-kus) - Thick and sticky like syrup.
    Example: Coal tar is viscous.
    
    

18. Petroleum (peh-tro-lee-um) - A dark oily liquid from underground used to produce petrol, diesel, kerosene, etc.
    Example: Petrol is obtained by refining petroleum.
    
    

19. Natural Gas (na-chu-rul gas) - A clean gaseous fuel found with petroleum, used in homes, factories, and vehicles.
    Example: Natural gas is used for cooking in some cities.
    
    

20. Compressed (kum-prest) - Pressed into a smaller space under high pressure.
    Example: CNG is compressed natural gas.
    
    

21. Global Warming (glo-bul wor-ming) - Gradual rise in Earth’s temperature due to pollution and greenhouse gases.
    Example: Burning fossil fuels causes global warming.
    
    

22. Conservation (kon-ser-vay-shun) - Saving and using resources wisely so they last longer.
    Example: Conservation of water and fuel is important.
    
    

23. Tar (taar) - Thick black liquid obtained from coal or petroleum, used in making roads.
    Example: Roads are sometimes coated with tar.

Textbook Exercise with Answers

1. What are the advantages of using CNG and LPG as fuels?

Answer: CNG (Compressed Natural Gas) and LPG (Liquefied Petroleum Gas) are clean fuels because they produce less air pollution compared to petrol, diesel, or coal. They are efficient and release a large amount of energy. LPG can be used in homes and industries for cooking and heating, while CNG is used as fuel for vehicles and power generation. CNG can be supplied through pipelines directly to homes and factories, which makes it convenient to use.

2. Name the petroleum product used for surfacing of roads.

Answer: The petroleum product used for surfacing of roads is bitumen. Bitumen is a sticky, black substance that is heated and spread on roads to make them smooth and durable.

3. Describe how coal is formed from dead vegetation. What is this process called?

Answer: Coal is formed from dead plants that lived millions of years ago in dense forests. These plants got buried under soil due to natural events like floods. Over millions of years, more soil layers covered them, and they sank deeper into the Earth. Under high pressure and high temperature, the dead plants slowly changed into coal. This slow process of converting dead vegetation into coal is called carbonisation. Since coal is formed from dead plants, it is also called a fossil fuel.

4. Fill in the blanks.

(a) Fossil fuels are coal, petroleum, and natural gas.
(b) The process of separation of different constituents from petroleum is called refining.
(c) The least polluting fuel for vehicles is CNG (Compressed Natural Gas).

5. Tick True/False against the following statements.

(a) Fossil fuels can be made in the laboratory. → False
(b) CNG is a more polluting fuel than petrol. → False
(c) Coke is almost pure form of carbon. → True
(d) Coal tar is a mixture of various substances. → True
(e) Kerosene is not a fossil fuel. → False

6. Explain why fossil fuels are exhaustible natural resources.

Answer: Fossil fuels like coal, petroleum, and natural gas are exhaustible resources because they are formed over millions of years from the remains of dead plants and animals. Their formation is extremely slow, and human consumption is much faster than their natural formation. If we continue to use them at a high rate, these resources may run out in a few hundred years. Therefore, we need to use fossil fuels carefully and conserve them.

7. Describe the characteristics and uses of coke.

Answer: Coke is a hard, black, and porous substance obtained by processing coal. It is almost pure carbon and does not burn easily like coal. Coke is used in the manufacture of steel and in the extraction of metals from their ores. It provides high heat required in industries and is considered a very important industrial fuel.

8. Explain the process of formation of petroleum.

Answer: Petroleum is formed from the remains of tiny plants and animals that lived in the sea millions of years ago. When these organisms died, their bodies settled at the bottom of the sea and got covered by layers of sand and clay. Over millions of years, under high pressure and high temperature and without air, the dead organisms slowly changed into petroleum and natural gas. Petroleum and natural gas are trapped in impervious rock layers above water because they are lighter than water and do not mix with it.

9. Graph Exercise 

The following Table shows the total power shortage in India from 1991–1997. Show the data in the form of a graph. Plot shortage percentage for the years on the Y-axis and the year on the X-axis. 

Answer:

Coal and Petroleum 

Combustion and Flame 

Conservation of Plants and Animals 

Cell - Structure and Functions