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CBSESecondary School (English Medium) (5 to 8) Class 8
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Non-crystalline/Amorphous Forms: Coal

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Topics

  • Introduction
  • Coal
  • Types of Coal
Maharashtra State Board: Class 9

Introduction:

Non-crystalline or amorphous forms of carbon lack a regular arrangement of carbon atoms. These forms are less structured compared to crystalline forms. Examples include coal and coke, which are widely used in various industrial and energy applications. Among these, coal is a significant fossil fuel that consists of carbon, hydrogen, oxygen, and small amounts of nitrogen, phosphorus, and sulphur. Coal occurs naturally in a solid state and is classified into four types based on its carbon content and formation process.

Maharashtra State Board: Class 7

Coal:

Coal is an important natural resource that has been used by humans for centuries to generate energy. It is called a fossil fuel because it is formed from the remains of ancient plants. These plants were buried millions of years ago under the ground due to natural events like floods or landslides. Over time, many layers of soil and rock formed on top of them, creating immense pressure. Along with this pressure, the heat from the Earth's interior slowly transformed the buried plant materials into a solid fuel known as coal.

  • Since coal was created from ancient plants, it contains energy that the plants captured from the sun through photosynthesis.
  • Over time, this energy got trapped in the form of carbon inside the coal. So, when we burn coal today, the stored energy is released as heat, which we can use to produce electricity or run industries.
  • Because it is made from plant remains, we call it a fossil fuel, similar to other fuels like oil and natural gas, which also come from ancient organic matter.

Formation of coal

Coal is found underground, not on the surface. People dig deep holes, called mines, to get it.

There are two main types of coal mines:

  • Open-pit mines: These are used when coal is near the surface. The upper layers of soil are removed to expose the coal.
  • Underground mines: These are deep tunnels dug into the ground to reach coal that lies far below the surface.
Maharashtra State Board: Class 7

Types of Coal:

Type of Coal Description Uses
Peat First stage in coal formation. Not fully coal, called a precursor Slowly changes to higher forms under pressure and heat
Lignite (Brown Coal) Lowest grade, soft and brown. Releases harmful gases when burned Used to generate electricity in power plants
Sub-bituminous Coal Better than lignite but lower quality than bituminous Produces steam to power electric plants
Bituminous Coal Hard and dense, black or dark brown. It has shiny and dull layers Generates electricity. Used to make coke for steel
Anthracite Coal Highest grade, shiny, black, and very hard Used for heating homes with less smoke
Graphite Hard to burn, not used as fuel Used in pencils and as a lubricant in powder form
Cannel Coal (Candle Coal) Smooth, fine-grained with high hydrogen content. Also called candle coal Historically used to make candles
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