Class 8. Science Coal and Petroleum

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Coal and petroleum are fossil fuels, which are the primary sources of energy for many of our daily activities. These resources take millions of years to form and are non-renewable, meaning they can be exhausted if used excessively.

1. Fossil Fuels
Fossil fuels like coal, petroleum, and natural gas are formed from the remains of dead plants and animals that were buried under the Earth's surface millions of years ago.
These fuels are called non-renewable resources because they cannot be replenished in a short period.
2. Coal
Coal is a black or brownish-black rock used primarily as fuel.
It is formed by the carbonization of plant material over millions of years under high pressure and temperature.
3. Types of Coal
Peat: Low-quality coal with low carbon content.
Lignite: A soft, brownish coal with more carbon than peat.
Bituminous: A harder form of coal with higher carbon content.
Anthracite: The highest quality coal with the highest carbon content.
4. Uses of Coal
Fuel for electricity generation in thermal power plants.
Domestic use for cooking and heating.
Industrial use for producing steel and other materials.
By-products like coal tar, coal gas, and coke are used in industries.
5. Petroleum
Petroleum (also called crude oil) is a thick, black liquid found deep under the Earth’s surface.
It is a fossil fuel formed from the remains of tiny marine organisms that were buried and subjected to heat and pressure over millions of years.
6. Refining of Petroleum
Petroleum refining is the process of separating the crude oil into useful components by a process called fractional distillation.
Petroleum is refined into various products such as:
Petrol (Gasoline): Used as fuel for vehicles.
Diesel: Used in trucks, buses, and some cars.
Kerosene: Used for cooking and heating.
Liquefied Petroleum Gas (LPG): Used for cooking and in industries.
Petroleum products like wax, lubricants, and chemicals are used to make everyday items like candles, ointments, and plastics.
7. Natural Gas
Natural gas is a fossil fuel found alongside petroleum.
It consists mostly of methane and is used as a clean fuel for domestic, industrial, and vehicular purposes.
Compressed Natural Gas (CNG) is used as a cleaner alternative to petrol and diesel for vehicles.
8. Advantages of Natural Gas
Cleaner fuel: Burns more cleanly than other fossil fuels, producing fewer pollutants.
Efficient: It is used for heating, cooking, and generating electricity.
9. Conservation of Fossil Fuels
Fossil fuels are non-renewable resources that are depleting rapidly due to excessive use.
Conservation methods include:
Using alternative energy sources like solar, wind, and hydropower.
Energy-efficient technologies: Reducing wastage of energy in industries and households.
Public awareness: Encouraging people to use fuels judiciously by reducing unnecessary consumption.
10. Harmful Effects of Using Fossil Fuels
Air Pollution: Burning fossil fuels releases harmful gases such as carbon dioxide, sulfur dioxide, and nitrogen oxides, contributing to air pollution.
Global Warming: Fossil fuel combustion releases large amounts of carbon dioxide, a greenhouse gas that contributes to global warming and climate change.
Acid Rain: Sulfur and nitrogen compounds released during the burning of coal and petroleum mix with rainwater to form acid rain, which damages crops, buildings, and aquatic life.
11. Alternative Sources of Energy
To reduce dependence on fossil fuels, we need to develop and use alternative energy sources, such as:
Solar energy: Using sunlight to produce electricity.
Wind energy: Using wind to generate power.
Hydropower: Using the energy of flowing water to generate electricity.
Biogas: Produced from organic waste and used as fuel.