October 05, 2022, 08:31:25 AM
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Topic: calculation and meaning of oxygen balance in explosives  (Read 1693 times)

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Offline Babcock_Hall

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Re: calculation and meaning of oxygen balance in explosives
« Reply #15 on: December 14, 2021, 02:27:19 PM »
Orcio_Dojek,

John Goodpaster used the word "decomposition," and Suzanne Bell used to word "combustion."  The equation you wrote For TNT is different from the formalism presented by either author.  Please refer to my opening post.

Offline Orcio_87

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Re: calculation and meaning of oxygen balance in explosives
« Reply #16 on: December 14, 2021, 02:37:40 PM »
As for formalism (for purpose of calculations) - OK. The oxygen balance assumes complete combustion (or decomposition if the oxygen is released) (C converts to CO2, H to H2O and so on...). Real detonation is the other thing.
« Last Edit: December 14, 2021, 03:00:12 PM by Orcio_Dojek »

Offline rolnor

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Re: calculation and meaning of oxygen balance in explosives
« Reply #17 on: December 15, 2021, 06:56:48 AM »
I think, with your formula, carbon dioxide would be a perfect high-explosive.
Both Suzanne Bell (p. 372) and John Goodpaster (p. 189) indicated that one starts by writing a balanced combustion equation, then calculating oxygen balance.  The equation CO2  :rarrow: CO2 is not meaningful; therefore, one should not calculate the oxygen balance at all.

When you wright like this I am not sure that you understand what I mean. Do you understand what makes one compound a high-explosive and the other not? You dont need a formula to see if a compound potentially can be a explosive. Maybe I expressed my self a bit stupid with the CO2-example.

Offline Babcock_Hall

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Re: calculation and meaning of oxygen balance in explosives
« Reply #18 on: December 15, 2021, 08:29:34 AM »
rolnor,

I think that the CO2 example was a bit of a distraction, but I welcome all attempts to work toward a better understanding of this topic.  Goodpaster defines explosives as "materials that undergo a rapid and energetic transformation into more stable substances, liberating large quantities of heat and gas."  This is concise and covers all of the points that I can think of.  I don't see the need to subdivide on the basis of low- versus high-explosives in this context; can you clarify?  It might be worthwhile to subdivide explosives into categories based on the type of chemical transformation.
« Last Edit: December 15, 2021, 09:23:18 AM by Babcock_Hall »

Offline rolnor

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Re: calculation and meaning of oxygen balance in explosives
« Reply #19 on: December 15, 2021, 09:50:28 AM »
I dont know, maybe high-explosive is just a word for me, I have not  seen the term low-explosive. I am not a native.
Yes, it can be pedagogic to group the compounds in categories.
Its different for nitro/nitrat and peroxy compounds compared to heavymetal azides for example, the azides dont involve redox processes really.

Offline Babcock_Hall

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Re: calculation and meaning of oxygen balance in explosives
« Reply #20 on: December 15, 2021, 10:35:25 AM »
High- versus low-explosives are differentiated on the basis of the speed of the reaction front, specifically whether it is greater than or less than the speed of sound.  One can imagine reactions  which involve little or no internal redox chemistry (Loss of a carboxyl group as carbon dioxide is technically a redox reaction in that the carbon is going from +3 to +4), but which generate lots of gaseous products.  Maybe azides fall into this category, but I have not looked into them in any depth.  One could differentiate those from reactions involving nitro groups or peroxides, in which redox chemistry is important.
EDT
Perhaps one way to differentiate substances is whether or not bonds to oxygen are forming to new atoms in the balanced equation.  This might differentiate nitro-type or peroxide-type reactions from a hypothetical reaction involving loss of carbon dioxide (or some other gas).  The latter might (in the universe of possibilities) create much gas, but the oxygen atoms are staying bound to carbon.
« Last Edit: December 15, 2021, 12:12:28 PM by Babcock_Hall »

Offline rolnor

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Re: calculation and meaning of oxygen balance in explosives
« Reply #21 on: December 15, 2021, 12:57:17 PM »
OK. I think in the case if peroxides, the oxygen atoms with broken  oxygen-oxygen-bonds will form new bonds with carbon so there is some sort of redox. Its probably complicated to seee exactly what happens. It will be water forming also so its a mix of reactions I guess.

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