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Author: Subject: Barium Chlorate
NitricSynth
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[*] posted on 26-2-2012 at 15:31
Barium Chlorate


I have worked with potassium chlorate a lot in pyrotechnics but I have a bunch of barium chlorate and I keep reading about barium chlorate compositions going up spontaneously.

Has anyone here worked with barium chlorate compatibility? I am thinking it just has the same acid incompatibilities as potassium chlorate and I have nothing to worry about, but I am not sure...
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TheChemINC
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[*] posted on 26-2-2012 at 15:39


i have heard of it being used in green star compositions for fireworks because of the brilliant colors that it produces, but the compositions are very sensitive....
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[*] posted on 26-2-2012 at 16:23


It is also hygroscopic, and moisture accelerates many spontaneous reactions which may have contributed to its bad name.



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[*] posted on 27-2-2012 at 09:09


If its used in commercial fireworks its probably relatively safe.



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[*] posted on 27-2-2012 at 09:22


It was used in French mole smokes, and may still be, it is a long time since I looked.
Like all soluble barium compounds it will be toxic.

http://en.wikipedia.org/wiki/Barium#Precautions
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[*] posted on 27-2-2012 at 09:40


But that's a little different, it would be less energetic than fireworks. Thus probably more sensitive.



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NitricSynth
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[*] posted on 27-2-2012 at 22:49


Quote: Originally posted by AirCowPeaCock  
If its used in commercial fireworks its probably relatively safe.


That's not really true... Add sulfur to a potassium chlorate composition and you will get auto-ignition spontaneously after a certain amount of time. Or when stars touch, during lift in the tube... Etc... KA BOOM!!!

Accidentally add a ammonium perchlorate star alongside potassium nitrate stars or with black powder and well have lots of fun!!! :D
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[*] posted on 28-2-2012 at 07:52


I should rephrase that. If its used in commercial fireworks its probably relatively safe <b>in some valuable situations</b>.



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[*] posted on 28-2-2012 at 10:05


The legends of the instability of potassium chlorate and sulfur has been largely overblown, and is primarily based upon accidents from probably 100+ years ago. With the purge of volcanic and sublimed sulfur from the industry these dangers are largely mitigated. Long gone are the days of self-ignition and spontaneous explosion on lift. That's not to say one should indiscriminately mix them or anything, but it's not unsafe to prime potassium chlorate stars with BP. They will not explode on the lift if you made the shell right. There are a few specialized effects and compositions that rely upon chlorate and sulfur or sulfide mixtures. When handled and prepared properly, these types of things can be used safely by experienced individuals.

Barium Chlorate on the other hands bring inherent danger with it. It is much less stable that potassium chlorate, and it's compositions are more prone to friction and impact. It does however produce some of the nicest colors available. The general industry standard is to use a mixture of potassium chlorate and/or barium nitrate with the barium chlorate as the oxidant. This reduces it's overall sensitivity, reduces cost, and improves the burn rate. For being relatively sensitive, it can actually have a rather sluggish burn rate.

I'm not sure where you heard or saw that barium chlorate is hygroscopic but that is really not true. Some of the impurities such as Barium Chloride or sodium chlorate may be to blame, but pure material is not really hygroscopic to any noticeable degree. Caking is not always indicative of being hygroscopic. It does cake like a bastard over time.
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[*] posted on 28-2-2012 at 10:47


How about the perchlorate? Is it more stable like with alkali metals? Or is it less stable like many transition metals?



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[*] posted on 28-2-2012 at 11:57
From RecPyro:


Some notes on Barium Chlorate chemistry (Tom Perigrin)

The ability of a molecule to act as an oxidizer is at best only vaguely related to the count of oxygens per molecule.
Barium chlorate has a formula weight of 304.23. Sure, there are 6 oxygens, but there is a lot of weight in the Barium atoms. A 100 gram sample of Barium Chlorate contains 31.55 grams of oxygen atoms. Potassium chlorate has a formula weight of 122.55, with 3 oxygens. This means that a 100 gram sample contains 39.17% oxygen. In fact, on a weight/weight basis, there is more oxygen in a gram of Potassium Chlorate than in a gram of Barium Chlorate.

Next - Barium surprisingly has essentially the same radius as Potassium. According to CRC, Crystal Ionic Radii, 59'th Ed, page F-213, the radii of Barium 2+ and Potassium + are 1.34 Ang, and 1.33 Ang respectively. (Why? There are two charges on the Ba, which means that the counterion is more strongly attracted, and quantum mechanical theory shows that when low lying d-orbitals are available there may be a surprising amount of electron density and back bonding in those orbitals, thus creating an anisotropic opportunity for unusually close approach). So, the difference in the crystal lattice stability cannot be ascribed to the difference in size (aka... "larger").

Then we get to the greater conundrum... heats of formation. Barium Chlorate is actually MORE stable than Potassium Chlorate, as regards formation from the elements. The heat of formation of Ba(ClO3)2 is -184.4 kcal/mol, while Potassium Chlorate is only -95.1 kcal/mol. However, the heat of decomposition as measured to stable products is much better for Ba(ClO3)2 at -28 kcal/mol, while it is only -10.6 kcal/mole for KClO3. How can this be? It's due to the fact that the products of decomposition are MUCH more stable in the Barium case than in the Potassium case. This means that more heat is released when Barium Chlorate decomposes. Thus, a small initial reaction returns more heat to the surrounding composition, thus more easily creating a runaway reaction.





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