Classifying materials as natural or man-made helps understand resource origins.
Natural resources include air, water, soil, and minerals.
Activity 3.2
Simulates resource consumption across generations using eatables (popcorn/peanuts/roasted gram/toffees).
Illustrates how consumption patterns affect resource availability for future generations.
Highlights the importance of responsible consumption.
Exhaustible natural resources like coal, petroleum, and natural gas were highlighted.
Fossil Fuels
Coal, petroleum, and natural gas are formed from the dead remains of living organisms (fossils).
3.1 Coal
Coal is a hard, black stone-like fuel.
Uses:
Cooking.
Railway engines (to produce steam).
Thermal power plants (to produce electricity).
Fuel in various industries.
Story of Coal
Formation: About 300 million years ago, dense forests in low-lying wetland areas were buried under soil due to natural processes like flooding.
Compression and increased temperature converted dead plants to coal.
Carbonisation: The slow conversion of dead vegetation into coal, as coal mainly contains carbon.
Coal is also called a fossil fuel because it was formed from the remains of vegetation.
Coal Products
Coal is processed in industry to get useful products:
Coke.
Coal tar.
Coal gas.
Coke
A tough, porous, and black substance; almost a pure form of carbon.
Uses: Manufacture of steel and extraction of many metals.
Coal Tar
A black, thick liquid with an unpleasant smell; a mixture of about 200 substances.
Products from coal tar are used as starting materials for manufacturing various substances in everyday life and industry, such as:
Synthetic dyes.
Drugs.
Explosives.
Perfumes.
Plastics.
Paints.
Photographic materials.
Roofing materials.
Naphthalene balls (used to repel moths) are also obtained from coal tar.
Coal Gas
Obtained during the processing of coal to get coke.
Used as a fuel in industries near coal processing plants.
Historically used for street lighting (e.g., London in 1810, New York around 1820).
Now used as a source of heat rather than light.
Bitumen, a petroleum product, is now used in place of coal-tar for metalling roads.
When heated in air, coal burns and produces mainly carbon dioxide gas (CO2).
3.2 Petroleum
Petrol is used as fuel in light automobiles (motorcycles, scooters, cars).
Diesel is used in heavy motor vehicles (trucks, tractors).
Petrol and diesel are obtained from petroleum, a natural resource.
The word petroleum is derived from petra (rock) and oleum (oil).
Formation of Petroleum
Formed from organisms living in the sea.
Dead organisms settled at the bottom of the sea and were covered with layers of sand and clay.
Over millions of years, in the absence of air, under high temperature and high pressure, the dead organisms transformed into petroleum and natural gas.
Location of Petroleum Deposits
The layer containing petroleum oil and gas is above that of water because oil and gas are lighter than water and do not mix with it.
The world’s first oil well was drilled in Pennsylvania, USA, in 1859.
In India, oil is found in Assam, Gujarat, Mumbai High, and in the river basins of Godavari and Krishna.
Refining of Petroleum
Petroleum is a dark oily liquid with an unpleasant odor; it is a mixture of various constituents.
Refining: The process of separating the various constituents/fractions of petroleum.
Carried out in a petroleum refinery.
Petrochemicals
Many useful substances are obtained from petroleum and natural gas.
Used in the manufacture of:
Detergents.
Fibers (polyester, nylon, acrylic, etc.).
Polythene and other man-made plastics.
Hydrogen gas (obtained from natural gas) is used in the production of fertilizers (urea).
Due to its great commercial importance, petroleum is also called ‘black gold’.
3.3 Natural Gas
An important fossil fuel that is easy to transport through pipes.
Stored under high pressure as compressed natural gas (CNG).
Uses:
Power generation.
Fuel for transport vehicles (less polluting, cleaner fuel).
CNG can be used directly for burning in homes and factories where it can be supplied through pipes.
A network of pipelines exists in Vadodara (Gujarat), some parts of Delhi, and other places.
Natural gas is also used as a starting material for the manufacture of a number of chemicals and fertilizers.
India has vast reserves of natural gas found in Tripura, Rajasthan, Maharashtra, and in the Krishna Godavari delta.
3.4 Some Natural Resources are Limited
Some natural resources are exhaustible (fossil fuels, forests, minerals, etc.).
Coal and petroleum formation requires millions of years, but known reserves will only last a few hundred years.
Burning these fuels is a major cause of air pollution and is linked to global warming.
It is necessary to use these fuels only when absolutely necessary to:
Result in better environment.
Reduce the risk of global warming.
Extend their availability.
Petroleum Conservation Research Association (PCRA) Tips for saving petrol/diesel while driving:
Drive at a constant and moderate speed as far as possible.
Switch off the engine at traffic lights or where you have to wait.
Ensure correct tire pressure.
Ensure regular maintenance of the vehicle.
Coal, petroleum and natural gas cannot be prepared in the laboratory from dead organisms because their formation is a very slow process and conditions for their formation cannot be created in the laboratory.
Exercises
Advantages of using CNG and LPG as fuels: cleaner, less polluting.
Petroleum product used for surfacing roads: Bitumen.
Coal formation from dead vegetation: Dead plants get buried under soil, compressed under high pressure and temperature, and slowly convert to coal. This process is called carbonisation.
Fill in the blanks:
(a) Fossil fuels are coal, petroleum, and natural gas.
(b) Process of separation of different constituents from petroleum is called refining.
(c) Least polluting fuel for vehicles is CNG.
True/False:
(a) Fossil fuels can be made in the laboratory. (F)
(b) CNG is a more polluting fuel than petrol. (F)
(c) Coke is almost a pure form of carbon. (T)
(d) Coal tar is a mixture of various substances. (T)
(e) Kerosene is not a fossil fuel. (F)
Fossil fuels are exhaustible because their formation takes millions of years, and their reserves are limited. Overuse leads to depletion.
Characteristics and Uses of Coke: Coke is a tough, porous, and black substance. It is an almost pure form of carbon. Coke is used in the manufacture of steel and in the extraction of many metals.
Process of Formation of Petroleum: Petroleum was 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, the absence of air, high temperature, and high pressure transformed the dead organisms into petroleum and natural gas.
Graph plotting for power shortage data (1991-1997) with years on the X-axis and shortage percentage on the Y-axis (Data provided in the transcript).