Learning Objectives
- Classify natural resources as exhaustible and inexhaustible
- Understand the formation and uses of coal
- Learn about petroleum, its refining, and products
- Understand the importance of conserving fossil fuels
Key Concepts
Natural Resources
Inexhaustible resources: Available in unlimited quantity and will not be depleted. Examples: sunlight, air, water.
Exhaustible resources: Present in limited quantity and will eventually run out. Examples: coal, petroleum, natural gas, minerals.
Coal
Coal is a hard, black fossil fuel. It was formed millions of years ago from the remains of dead plants buried under the earth. Due to high temperature and pressure, these plant remains were slowly converted to coal. This process is called carbonisation.
Types of coal (by carbon content): peat → lignite → bituminous → anthracite (highest carbon content, best quality).
Products from coal processing:
- Coke: Almost pure carbon, used in steel manufacturing and as a fuel.
- Coal tar: A thick, black liquid used to manufacture synthetic dyes, drugs, explosives, perfumes, plastics, paints, and roofing materials.
- Coal gas: Obtained during processing of coal to get coke. Used as fuel in industries.
Petroleum
Petroleum is a dark, oily liquid found trapped between layers of rocks beneath the earth's surface. It was formed from organisms living in the sea millions of years ago. It is called "black gold" due to its high value.
Refining of Petroleum: Petroleum is refined at a refinery by heating and separating it into useful fractions based on their boiling points. This process is called fractional distillation.
Products of petroleum refining (in order of increasing boiling point):
- LPG (Liquefied Petroleum Gas) — cooking fuel
- Petrol (gasoline) — motor fuel
- Kerosene — fuel for stoves and jet engines
- Diesel — fuel for heavy vehicles
- Lubricating oil — lubrication of machines
- Paraffin wax — candles, Vaseline
- Bitumen — road surfacing
Natural Gas
Natural gas is a clean-burning fossil fuel found along with petroleum deposits. It is mainly composed of methane (CH₄). CNG (Compressed Natural Gas) is used as a vehicle fuel and is less polluting than petrol or diesel.
Conservation of Fossil Fuels
Fossil fuels take millions of years to form and are being consumed at an alarming rate. Conservation measures include using public transport, carpooling, using CNG vehicles, switching off appliances when not in use, and developing alternative energy sources.
Summary
Coal, petroleum, and natural gas are fossil fuels formed over millions of years from dead organisms. Coal gives coke, coal tar, and coal gas. Petroleum is refined into petrol, diesel, kerosene, LPG, and other products. These resources are exhaustible and must be conserved for future generations.
Important Terms
- Fossil Fuel: Fuel formed from the remains of ancient organisms (coal, petroleum, natural gas)
- Carbonisation: The slow process of conversion of dead plant matter into coal
- Coke: Almost pure carbon obtained from coal, used in steel making
- Petroleum: Liquid fossil fuel refined into many products; called "black gold"
- Fractional Distillation: Separating petroleum into fractions by boiling point
- CNG: Compressed Natural Gas, a cleaner fuel for vehicles
Quick Revision
- Fossil fuels: coal, petroleum, natural gas — exhaustible resources
- Coal formed by carbonisation of dead plants over millions of years
- Coal products: coke, coal tar, coal gas
- Petroleum products (by boiling point): LPG → petrol → kerosene → diesel → lubricating oil → paraffin wax → bitumen
- Natural gas: mainly methane, cleaner fuel, used as CNG
- PCRA advises conservation: save fuel, use public transport