Chemistry Forums for Students > Organic Chemistry Forum for Graduate Students and Professionals

calculation and meaning of oxygen balance in explosives

(1/5) > >>

Babcock_Hall:
Hi Everyone,

A common subject in forensic chemistry is explosives.  One concept that arises is that of oxygen balance.  One writes a balanced equation for an explosive compound assuming that all hydrogens are in water, all carbons are in carbon dioxide, and all nitrogens are in N2.  One then calculated whether the number of oxygen atoms is less than, equal to, or greater than the number needed in the balanced equation.  Based on an example, it seems that O2 is written on the product side with either a + or a - sign in front.  If the formula of the explosive is CaHbNcOd, the the oxygen balance is d - 2a - 1/2b (Bell S, Forensic Chemistry, 2nd ed., p. 395; she acknowledges that this method has shortcuts).  For TNT the number is -74.0%, and for NG it is +3.5%.  These numbers are weight percents.  Suzanne Bell wrote. "The oxygen balance gauges are useful for designing explosive formulations that come close to having a next zero oxygen balance."

In Chapter 5 of Forensic Chemistry: Fundamentals and Applications (Siegel J, ed), John Goodpaster also discussed the concept of oxygen balance on pages 189-191.  He wrote that an oxygen balance of zero should achieve the greatest explosive power.  He noted that one can combine explosives in a mixture to achieve an oxygen balance of near zero.  Yet he also wrote that this is not the sole factor that is considered in formulating commercial mixtures of explosives.

Recently in a thread on the explosion of a mesylate in this sub-forum, the question of oxygen balance came up.  I have two questions.  One is how should other elements be treated in a balanced equation of a compound containing sulfur, for example?  Two in evaluating the possibility of an explosion hazard in a novel compound, does the concept of oxygen balance provide any useful information?  My very provisional answer to the latter question is that there is limited value.

rolnor:
This calculations are usefull when you have nitro groups in the molecule, you can not use them for any molecule containing oxygen and carbon. Also if you have peroxide groups it can probably be used. You need a system where moving oxygen from one atom to another releases energy. If you have acetone peroxide, breaking the weak oxygen-oxygen bond and creating two carbon-oxygen bonds instead releases energy.

Babcock_Hall:
Triacetonetriperoxide is an example of a peroxide-containing explosive, but I suspect that you already knew this.

rolnor:
I missed your reply, please read my

rolnor:
I think, with your formula, carbon dioxide would be a perfect high-explosive.

Navigation

[0] Message Index

[#] Next page