Coal is a combustible black or brownish-black sedimentary rock composed mostly of carbon and hydrocarbons. It is the most abundant fossil fuel on the planet and has been used for centuries as a source of energy. Coal is formed from the remains of ancient plants and trees that were buried and subjected to geologicalpressure and heat over millions of years.
Types of Coal
There are four main types of coal:
Anthracite: This is the highest quality coal, known for its high carbon content and low impurities. It is hard, black, and has a high energydensity.
Bituminous: Bituminous coal is a dense, black coal that is often used for heating and electricity generation. It has a higher energy content than lignite and sub-bituminous coal.
Sub-bituminous: This type of coal is black in color and has a higher moisture content than bituminous coal. It is commonly used for electricity generation.
Formation of Coal
Coal is formed from the remains of plants and trees that lived millions of years ago. When these organic materials died, they accumulated in swamps and peat bogs. Over time, the accumulated plantmatter was buried under layers of sediment, and as more and more sediment accumulated, the heat and pressure from the overlying layers caused the plantmaterial to undergo chemical and physicalchanges, eventually forming coal.
Uses of Coal
Coal has been used for various purposes, including:
Develop a model to illustrate that the release or absorption of energy from a chemical reaction system depends upon the changes in total bond energy.
Energy
Students who demonstrate understanding can:
Create a computational model to calculate the change in the energy of one component in a system when the change in energy of the other component(s) and energy flows in and out of the system are known.
Plan and conduct an investigation to provide evidence that the transfer of thermal energy when two components of different temperature are combined within a closed system results in a more uniform energy distribution among the components in the system (second law of thermodynamics).