General Properties:
* Solid: Coal is a solid, brittle material.
* Color: Typically black or brownish-black, but can range from dark brown to almost silver-grey.
* Luster: Coal usually has a dull or earthy luster.
* Hardness: Varies depending on the type, but generally soft (can be scratched with a fingernail).
* Density: Varies depending on the type, but generally ranges from 1.2 to 1.5 g/cm³.
* Porosity: Coal can be porous, meaning it contains small holes and spaces.
* Brittleness: Coal is brittle and easily broken.
* Conductivity: Coal is a poor conductor of heat and electricity.
Specific Properties Varying by Coal Type:
* Moisture Content: Ranges from 0-40% depending on the type, higher in younger coals.
* Volatile Matter: The amount of gases released when coal is heated. Higher in younger coals, meaning they burn quickly and with more flame.
* Fixed Carbon: The amount of carbon remaining after volatile matter is removed. Higher in older coals, meaning they burn with a higher heat output and leave less ash.
* Ash Content: The inorganic material remaining after coal is burned. Varies depending on the source and origin of the coal.
* Calorific Value: The amount of heat released when coal is burned. Higher in older coals, meaning they have a higher energy content.
Other Notable Physical Properties:
* Texture: Coal can have different textures, from smooth to rough, depending on its composition and origin.
* Fracture: Coal usually fractures irregularly, breaking into uneven pieces.
* Streak: Coal has a black or brownish-black streak, which is the color of the powder produced when it is rubbed against a streak plate.
Understanding the physical properties of coal is crucial for its various applications, from power generation to steel production and other industrial uses.
