stoichiometry of cu benzoate and ap

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Sulphurstan
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stoichiometry of cu benzoate and ap

Post by Sulphurstan »

Hello.
I'm trying to find the exact stoichiometry of AP and Cu(C6H5COO)2.....
I know the products may depend from the conditions (T and p), but still, is there a trick to find my way from a strictly chemical point of view?
The composition AP/CuBenzo/Hexamine (70/20/10) could be a start, but still, I'm not satisfied with the approach...
Any help/trick/idea welcomed.
Thanks in advance
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Lloyd
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Re: stoichiometry of cu benzoate and ap

Post by Lloyd »

Sulfur,
I have a fairly-good 'feel' for how chemicals react with one-another, especially when compounding new star compositions. But I'm not a 'numbers' chemist -- only empirical. So I cannot help.

If I had to guess, Richard would be one of the most-likely to contribute to your answer.

Lloyd
"Pyro for Fun and Profit for More Than Sixty Years"
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richardh08
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Re: stoichiometry of cu benzoate and ap

Post by richardh08 »

The only way I know of getting an answer is by doing the sums. I'm just off to bed but I'll have a look at the problem tomorrow.
Even when I'm wrong, I'm convincing.
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richardh08
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Re: stoichiometry of cu benzoate and ap

Post by richardh08 »

To fully oxidize Cu benzoate, the reaction is:
12NH4ClO4 + Cu(C6H5COO)2 -> 6N2 + 12HCl + 23H2O + 14CO2 + CuO
That corresponds to a mixture of 83.4% AP to 16.6% Cu benzoate. I'm assuming the HCl and CuO will react in the flame to produce CuCl

About the most extreme ratio you could get away with is to oxidize all the carbon to CO instead of CO2, in which case the ratios are 72.8% AP to 27.2% Cu benzoate.

Somewhere between these two might prove to be the ideal mixture. In that respect, I note that Dave Bleser's blue is 79.2% AP, 17.4% Cu benzoate and 3.4% dextrin.

If you are intending to include hexamine, then it will be fully oxidized in a mixture of 85.8% AP and 14.2% hexamine.

I hope that helps.
Even when I'm wrong, I'm convincing.
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Lloyd
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Re: stoichiometry of cu benzoate and ap

Post by Lloyd »

Richard,
This, coming from a strictly 'empirical' guy -- I greatly respect your knowledge of stoichiometry! It would have been a wonderful skill to have over the years!

Empirical work can produce nice effects, but one needs a 'starting place' with new formulae, and that's where your skill comes in.

Lloyd
"Pyro for Fun and Profit for More Than Sixty Years"
Sulphurstan
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Re: stoichiometry of cu benzoate and ap

Post by Sulphurstan »

Richard.
Thanks a lot for this equation. On another welknown forum, from another -probably also well-known - chemist, he gave the same proportion, but slightly different products CuCl2 being one of them... Nevertheless 12 AP and 1 CuBenzo are same proportons in both equations -> i have my starting point.

Regarding hexamine, you are exactly on the point, i wish to investigate: adding it lowers the flame temperature, but could also (maybe?) generate some Cu (OH)2, with the green band i would like to avoid... And here the empirical approach, testing, mixing, feeling will tell!

As I'm in the blue flame subject, i take the liberty to ask another question. Kosankes The chemistry, physics and perception of colored flames states that the blue light is more energetic than the red one. what i understand from quantum theory (electron energy levels): the output photon's energy is strictly related to the input energy which make the electrons reach the excited state: the higher the jump, the higher the photon energy. Thus blue, being highly energetic should come for a high energy input (high temperature!), and here: blocked, brain stucked. What the heck didnt i mis-understand? :roll: :o :shock: :?:

Lloyd: i know that nice working formulas must not necessary be thinked out that way (triangle diagrams are the tool to do it), but it is just the thrill for me to UNDERSTAND chemistry a little deaper than redox
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richardh08
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Re: stoichiometry of cu benzoate and ap

Post by richardh08 »

Thanks for the compliment, Lloyd. But - honestly - it's really not that difficult a thing to do, once you have got the hang of it.
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richardh08
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Re: stoichiometry of cu benzoate and ap

Post by richardh08 »

Sulphur,

I'm guessing the equation your chemist gave was something like:
12NH4ClO4 + Cu(C6H5COO)2 -> 6N2 + 10HCl + 24H2O + 14CO2 + CuCl2
It just shuffles a few atoms around in the products and, as you say, doesn't alter the stoichiometry of the reactants. I would be surprised if, in the real case, both reactions (and probably several others) weren't going on simultaneously.

I thought that might be why you were thinking of adding hexamine, as it is reputed to both increase the flame envelope and lower the temperature. I agree that, with such a mixture, trial and error is the only feasible route.
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richardh08
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Re: stoichiometry of cu benzoate and ap

Post by richardh08 »

Sulphur,
On your other point, you have to understand that there are at least two things that are happening. While it is true that a blue photon has more energy than a red one, you can't get a given substance to switch it's emission from red to blue just by making it hotter. (Well, you can if the emitter is behaving as a 'black body', but that's a different story.)

The colour of the light emitted by a molecule (or an atom) is entirely determined by what goes on inside the molecule, in terms of the allowed energy levels for its electrons. Supplying energy just moves the electrons from one level to another, but doesn't change the energy levels themselves. Eventually, the electrons will make transitions back to the lower levels, emitting light of one or more of a fixed set of colours.

CuCl molecules are held together by relatively weak chemical bonds, so the effect of making the flame hotter is to cause the molecule to break apart into Cu and Cl atoms (which will then combine with other atoms to form different, more stable molecules). If the CuCl molecules don't exist, they can't emit. That's why CuCl blues need a relatively low flame temperature.
Even when I'm wrong, I'm convincing.
Sulphurstan
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Re: stoichiometry of cu benzoate and ap

Post by Sulphurstan »

Wouah, if you'd have been my chemistry teacher 25 years ago, I'll probably not have the same job today !
Got the thing about the low bonds in CuCl explaining the low temperature!
Thanks really
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Boophoenix
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Re: stoichiometry of cu benzoate and ap

Post by Boophoenix »

Most of all of that is way above my pay grade. Thanks Richard for writing it in a way I didn’t feel like a complete idiot, lol

I’m gonna have to save this for future reading. Something in there almost made since. Which is pretty weird for that to happen to me on this line of discussion.
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