Energy of chemical explosions

The blast wave resulting from a chemical explosion is generated by the rapid expansion of gases at the explosion site. This expansion can be caused by two mechanisms (1) thermal heating of the reaction products and (2) the change in the total number of moles by reaction. 

For most hydrocarbon combustion explosions in air the change in the number of moles is small. For example, consider the combustion of propane in air. The stoichiometric equation is 

The initial number of moles on the left-hand side is 24.8, and the number of moles on the right-hand side is 25.8. In this case only a small pressure increase is expected as a result of the change in the number of moles, and almost all the blast energy must be due to thermal energy release. 

Doolittle, G. A. Fitzgerald, and M. J. Tang, Recent Developments in the Baker-Strehlow VCE Analysis Methodology, Process Safety Progress (1998), 17(4) 297. 

Appendix B contains energy of explosion values based on thermodynamic availability. 

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