🌍 Coal and Petroleum – Class 8 Science (Detailed Notes)

🔹 1. Introduction: Our Dependence on Natural Resources

• All living beings need energy to survive.
• Plants get energy from the Sun 🌞.
• Humans and animals depend on plants (directly/indirectly).
• But for industries, vehicles, cooking, electricity → we depend on fuels.

👉 Two most important natural fuels are Coal and Petroleum.
They are called fossil fuels because they are formed from dead plants and animals buried millions of years ago.

🔹 2. What are Fossil Fuels?

• Definition: Fossil fuels are natural fuels formed from the remains of dead plants and animals, buried deep under the earth for millions of years.
• Examples: Coal, Petroleum, Natural Gas.
• Why important? → They give us energy 💡, power machines, produce electricity, and are raw materials for many industries.

⚠️ Problem: Fossil fuels are non-renewable. Once finished, they take millions of years to form again.

🔹 3. Coal – The Black Gold 🪨

(a) Formation of Coal

• About 300 million years ago, dense forests grew in low-lying wetland areas.
• Trees and plants died, fell into swamps, and were buried under soil.
• With high pressure & temperature, over millions of years, dead plants → coal.
• Process = Carbonisation (plants → carbon-rich coal).

(b) Types of Coal (based on carbon content)

1. Peat → low carbon, smoky fuel.
2. Lignite → brown coal, soft.
3. Bituminous → most used, good energy.
4. Anthracite → hardest, purest (almost 90% carbon).

(c) Uses of Coal

• Fuel in homes & industries 🔥.
• Thermal power plants → electricity ⚡.
• Manufacture of steel, cement.
• Source of by-products (coke, coal tar, coal gas).

🔹 4. By-products of Coal

(a) Coke

• Almost pure carbon.
• Hard, porous, black.
• Used in steel industry and as fuel.

(b) Coal Tar

• Thick black liquid with unpleasant smell.
• Mixture of 200+ substances.
• Used for: dyes, drugs, explosives, perfumes, paints, naphthalene balls.

(c) Coal Gas

• Obtained during processing of coal to get coke.
• Used as fuel in industries near coal processing plants.

🔹 5. Petroleum – The Black Gold ⛽

(a) Formation of Petroleum

• Millions of years ago, dead tiny marine plants & animals settled at bottom of seas. 🌊
• Covered with layers of sand & clay.
• Heat + pressure for millions of years → oil & natural gas trapped in rocks.

(b) Petroleum Refining

• Petroleum = mixture of many useful substances.
• Refining = separating petroleum into different products in a petroleum refinery.
• Process = Fractional distillation (different products separated at different boiling points).

(c) Petroleum Products & Uses

1. Petrol (Gasoline) → cars, scooters 🚗.
2. Diesel → buses, trucks, generators.
3. Kerosene → cooking, lamps.
4. LPG (Liquefied Petroleum Gas) → domestic fuel.
5. Lubricating Oil → machines.
6. Paraffin Wax → candles 🕯️, ointments, vaseline.
7. Bitumen → roads construction 🛣️.

🔹 6. Natural Gas – The Clean Fuel 💨

• Found with petroleum.
• Stored under high pressure as CNG (Compressed Natural Gas).
• Uses:
  • Vehicles (eco-friendly).
  • Power generation.
  • Fertiliser industry.
  • Cooking fuel in homes.
• Example in India: Mumbai High, Krishna-Godavari Basin.

🔹 7. Advantages of Fossil Fuels

✔️ Easily available.
✔️ High energy content.
✔️ Useful by-products.
✔️ Drive industrial growth.
✔️ Run transport system.

🔹 8. Disadvantages of Fossil Fuels ⚠️

❌ Non-renewable → once finished, cannot be replaced soon.
❌ Burning produces carbon dioxide → global warming 🌍🔥.
❌ Causes air pollution → smog, acid rain, respiratory diseases.
❌ Oil spills harm marine life.
❌ Mining of coal = land degradation & health hazards for miners.

🔹 9. Conservation of Fossil Fuels

🌱 We must use them wisely because they are limited.
Ways to conserve:

1. Use public transport instead of private cars.
2. Switch off lights & fans when not needed.
3. Use energy-efficient appliances (LED bulbs).
4. Promote alternative energy sources – solar, wind, hydro.
5. Avoid wastage of fuel in cooking.
6. Follow 3 R’s – Reduce, Reuse, Recycle.

🔹 10. Alternatives to Fossil Fuels 🌞🌬️💧

• Solar energy ☀️ – unlimited, eco-friendly.
• Wind energy 🌬️ – windmills generate electricity.
• Hydropower 💧 – dams convert water flow to energy.
• Biogas – made from cow dung, kitchen waste.
• Hydrogen fuel – clean future fuel.

🔹 11. Flowchart: Formation of Fossil Fuels

Plants & Animals (buried) → Heat + Pressure → Fossil Fuels (Coal, Petroleum, Natural Gas)

🔹 12. Key Differences Between Coal and Petroleum

🔹 13. Quick Revision (Exam Pointers 📝)

• Coal → formed from plants (Carbonisation).
• Petroleum → formed from marine organisms.
• Coal by-products → coke, coal tar, coal gas.
• Petroleum refining → fractional distillation.
• CNG → eco-friendly fuel.
• Fossil fuels = non-renewable, cause pollution.
• Conservation = must use wisely.

🎯 Final Words

Coal and Petroleum are called Black Gold because they are very valuable.
But if we overuse them, the world may face energy crisis and climate disasters.
So, let us use fossil fuels carefully and switch to renewable energy sources for a sustainable future. 🌱🌍