Editing Energy value of coal (section)

==Chemical composition==
Chemical composition of the coal is defined in terms of its proximate and ultimate (elemental) analyses. The parameters of proximate analysis are [[moisture]], [[Volatility (chemistry)|volatile]] matter, ash, and fixed carbon. Elemental or ultimate analysis encompasses the quantitative determination of [[carbon]], [[hydrogen]], [[nitrogen]], [[sulfur]] and [[oxygen]] within the coal. Additionally, specific physical and mechanical properties of coal and particular [[coal assay|carbonization]] properties 

The [[calorific value]] ''[[Heat|''Q'']]'' of coal [kJ/kg] is the heat liberated by its complete [[combustion]] with oxygen. ''Q'' is a complex function of the elemental composition of the coal{{cn|date=June 2022}}. ''Q'' can be determined [[experiment]]ally using calorimeters. [[Pierre Louis Dulong|Dulong]] suggests the following approximate formula for ''Q'' when the oxygen content is less than 10%: 

:''Q'' = 337''C'' + 1442(''H'' - ''O''/8) + 93''S'',

where ''C'' is the mass percent of carbon, ''H'' is the mass percent of hydrogen, ''O'' is the mass percent of oxygen, and ''S'' is the mass percent of sulfur in the coal.  With these constants, ''Q'' is given in kilojoules per kilogram.