What Is Coal and Petroleum Class 8: Complete Science Guide

Definition and Formation of Coal and Petroleum

Coal and petroleum are natural fossil fuels that provide energy. Coal forms from dead plants buried under layers of soil and rock millions of years ago. Over time, heat and pressure transformed this plant material into coal. Petroleum, or crude oil, formed mainly from tiny marine animals and plants that settled on the sea floor and got buried under sediments. Heat and pressure converted these remains into petroleum.

• Coal formation: Dead plants → buried → heat & pressure → coal
• Petroleum formation: Marine organisms → buried → heat & pressure → petroleum

Both processes take millions of years, making coal and petroleum non-renewable resources.

Types of Coal and Their Uses

Coal is classified into four main types based on carbon content and energy value:

Uses of coal:

• Generating electricity in thermal power plants
• Producing steel by providing carbon in blast furnaces
• Domestic heating and cooking in some regions

Coal’s high carbon content makes it a valuable fuel but also a source of pollution.

Petroleum: Composition, Extraction, and Products

Petroleum is a complex mixture of hydrocarbons found beneath the earth's surface. It is extracted by drilling oil wells. After extraction, petroleum is refined to separate useful products:

• Petrol (gasoline): Used as fuel in vehicles
• Diesel: Fuel for trucks, buses, and some cars
• Kerosene: Used for cooking and lighting
• Lubricants: Reduce friction in machines
• Petrochemicals: Raw materials for plastics, synthetic fibers, and chemicals

The refining process involves heating petroleum to separate these products based on boiling points.

Example: If crude oil is heated, lighter fractions like petrol evaporate first, while heavier ones like bitumen remain.

Comparison Between Coal and Petroleum

Here is a comparison table to understand coal and petroleum better:

This comparison helps students remember key differences for exams.

Environmental Impact and Conservation of Coal and Petroleum

Using coal and petroleum has environmental consequences:

• Burning coal releases smoke, ash, and greenhouse gases causing air pollution and climate change.
• Petroleum extraction can lead to oil spills harming marine life.
• Both contribute to global warming due to carbon dioxide emissions.

Conservation methods:

• Using renewable energy sources like solar and wind
• Improving fuel efficiency in vehicles and industries
• Recycling and using alternative fuels

Students should understand the need to use these fuels wisely to protect the environment.

Worked Example: Calculating Energy from Coal

Suppose 1 kg of bituminous coal produces 24 MJ (megajoules) of energy.

Question: How much energy will 5 kg of coal produce?

Solution:

Energy produced = Energy per kg × Mass

$$E = 24 \text{ MJ/kg} \times 5 \text{ kg} = 120 \text{ MJ}$$

So, 5 kg of coal produces 120 MJ of energy.

This simple calculation helps understand the energy potential of coal.