Editing Propane (section)

=== Energy content ===
The [[enthalpy]] of combustion of propane gas where all products return to standard state, for example where water returns to its liquid state at standard temperature (known as [[Heat of combustion#Higher heating value|higher heating value]]), is (2,219.2 ± 0.5) kJ/mol, or (50.33 ± 0.01) MJ/kg.<ref name="nist">[http://webbook.nist.gov/cgi/cbook.cgi?ID=C74986&Units=SI&Mask=1#Thermo-Gas Propane]. NIST Standard Reference Data referring to {{Cite journal | last1 = Pittam | first1 = D. A. | last2 = Pilcher | first2 = G. | doi = 10.1039/f19726802224 | title = Measurements of heats of combustion by flame calorimetry. Part 8.—Methane, ethane, propane, n-butane and 2-methylpropane | journal = Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases | volume = 68 | pages = 2224 | year = 1972 }} and {{cite journal|author=Rossini, F.D.|title= Calorimetric determination of the heats of combustion of ethane, propane, normal butane, and normal pentane|journal=  Bureau of Standards Journal of Research|year= 1934|volume= 12|issue= 6|pages= [https://archive.org/details/calorimetricdete12673ross/page/735 735]–750|url=https://archive.org/details/calorimetricdete12673ross|doi=10.6028/jres.012.059|doi-access= free}}</ref>

The enthalpy of combustion of propane gas where products do not return to standard state, for example where the hot gases including water vapor exit a chimney, (known as [[Heat of combustion#Lower heating value|lower heating value]]) is −2043.455 kJ/mol.<ref>{{cite book|last1=Ҫengel|first1=Yunus A.|last2=Boles|first2=Michael A.|title=Thermodynamics: An Engineering Approach|date=2006|publisher=McGraw Hill|isbn=978-0-07-288495-1|page=925|edition=Fifth}}</ref>  The lower heat value is the amount of heat available from burning the substance where the combustion products are vented to the atmosphere; for example, the heat from a fireplace when the flue is open.