Chapter 5: Coal and petroleum

These NCERT Class 8 Science Chapter 5 notes explain coal and petroleum as important fossil fuels. The chapter focuses on how these fuels were formed millions of years ago and why they are considered non-renewable resources.

It discusses coal and its products like coke, coal tar and coal gas. It also explains petroleum, refining process, fractional distillation and different petroleum products such as petrol, diesel and LPG.

Chapter 5 – Coal and Petroleum is important for understanding energy resources, conservation and environmental impact. It is highly relevant for school examinations and foundation level competitive preparation.

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1. Introduction: why coal and petroleum are important

• Coal and petroleum are important natural resources found inside the Earth.
• They are major energy resources used in homes, industries and transport.
• These resources were formed millions of years ago from dead plants and animals.
• They provide fuel for electricity generation and vehicles.
• Petrol used in cars today comes from ancient living organisms buried deep under the sea.

2. What are fossil fuels?

• Fossil fuels are fuels formed from dead plants and animals buried under the Earth.
• They were formed under high pressure and high temperature over millions of years.
• Examples include coal, petroleum and natural gas.
• Fossil fuels are limited in quantity.
• They are classified as non-renewable resources.

3. Coal and its uses

• Coal is a hard, black substance mainly made of carbon.
• It is used as a fuel in industries.
• Coal is used to generate electricity in thermal power plants.
• It plays an important role in making steel.
• Coal is one of the oldest fossil fuels used by humans.

4. Products of coal

• Coal gives three important products: coke, coal tar and coal gas.
• Coke is almost pure carbon and is hard and porous, used in fuel and steel making.
• Coal tar is a thick black liquid used in roads, dyes, drugs and roofing materials.
• Coal gas is a gaseous fuel obtained during coal processing.
• These products are obtained during destructive distillation of coal.

5. Petroleum and crude oil

• Petroleum is a dark, oily liquid found deep under the Earth.
• It is also called crude oil.
• Petroleum is a major source of fuels like petrol and diesel.
• It is found trapped between layers of rocks.
• Petroleum is processed to obtain useful substances.

6. Refining of petroleum

• Refining is the process of separating petroleum into useful parts.
• Refining is done in a petroleum refinery.
• The process used is called fractional distillation.
• Different products are separated based on their boiling points.
• Refining produces fuels and other valuable materials.

7. Petroleum products and their uses

• LPG is used as cooking fuel in homes.
• Petrol is used as fuel for cars and two-wheelers.
• Diesel is used in buses, trucks and generators.
• Kerosene is used as fuel in stoves and lamps.
• Other products include lubricating oil for machines, paraffin wax for candles and bitumen for road surfacing.

8. Natural gas and its advantages

• Natural gas is the cleanest fossil fuel and is found along with petroleum.
• It is used for cooking as PNG and in vehicles as CNG.
• It is also used for power generation.
• Natural gas produces less pollution compared to other fuels.
• It has high energy output and burns completely.

9. Non-renewable and exhaustible resources

• Non-renewable resources are resources that cannot be replaced quickly.
• Coal, petroleum and natural gas are examples of non-renewable resources.
• Exhaustible resources are limited in quantity and can get exhausted.
• In contrast, inexhaustible resources like sunlight and air are unlimited.
• Proper use of exhaustible resources is necessary for future generations.

10. Petrochemicals and their importance

• Petrochemicals are chemicals obtained from petroleum.
• They are used to make plastics and synthetic fibres.
• Petrochemicals are also used in detergents and other products.
• Many daily use items are made from petrochemical products.
• Petrochemicals have replaced many natural materials.

11. Conservation of fossil fuels

• Fossil fuels are limited and will finish one day if overused.
• Excessive use of fossil fuels causes pollution.
• Conservation means careful and planned use of resources.
• Using public transport and saving electricity help conserve fuels.
• Using renewable energy like solar and wind reduces dependence on fossil fuels.

12. Key exam-oriented keywords explained

• Fossil fuels: Fuels formed from dead plants and animals over millions of years.
• Coal: A hard black fossil fuel mainly made of carbon.
• Coke: Almost pure carbon obtained from coal.
• Coal tar: Thick black liquid obtained from coal, used in roads and chemicals.
• Coal gas: Gaseous fuel produced during processing of coal.
• Petroleum: Dark oily liquid fossil fuel also called crude oil.
• Crude oil: Unrefined petroleum obtained from underground.
• Refining: Process of separating crude oil into useful products.
• Fractional distillation: Method used in refineries to separate petroleum components.
• Natural gas: Clean fossil fuel used as CNG and PNG.
• Non-renewable resources: Resources that cannot be replaced quickly.

13. One-page summary for quick revision

• Coal, petroleum and natural gas are fossil fuels.
• Coal gives important products like coke, coal tar and coal gas.
• Petroleum is refined by fractional distillation to obtain fuels.
• Fossil fuels are non-renewable and exhaustible resources.
• Conservation of fossil fuels is essential for sustainable development.

Understanding NCERT Class 8 Science Chapter 5 is essential to learn about fossil fuels and their importance in daily life. The chapter clearly explains refining, natural gas and conservation of exhaustible resources.

The concepts help students understand sustainable use of energy and environmental responsibility. It is highly useful for school exams and foundation competitive preparation.

Continue reading NCERT Class 8 Science Chapter 6 – Combustion and Flame to understand burning processes and fuel efficiency.

FAQs

Q1. What are fossil fuels?
Fossil fuels are fuels formed from the remains of dead plants and animals over millions of years under high pressure and temperature.

Q2. What are the main products of coal?
The main products of coal are coke, coal tar and coal gas.

Q3. What is refining of petroleum?
Refining is the process of separating crude oil into useful components through fractional distillation.

Q4. Why are fossil fuels called non-renewable resources?
They are called non-renewable because they take millions of years to form and cannot be replaced quickly.

Q5. Why is this chapter important for exams?
It explains energy resources, conservation and environmental issues, which are important for school exams and foundation preparation.

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