madscientist
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Hypobromite?
I just got done with an experiment a few minutes ago. Here's what I did and what happened.
I mixed 8.2g of granulated NaBr with 5.7g of granulated Ca(OCl)2. After about ten minutes, it transformed from a white mixture to a pale yellowish
color. I then added 2mL of water to accelerate the reaction. Within fifteen seconds the mix was the color of orange citrus - it wasn't exactly a *wet*
mix, but it was clumpy. I let it sit for ten minutes, and no additional change was observed. I decided I would begin to heat it, to see if bromine
would boil off (it boils around 58C). After the temperature reached 55C the mix began to darken slightly. Around 60C the mix began to crackle very
faintly. Visible quantities of bromine weren't given off until the temperature reached 81C. And so, here is my theory for what happened. Keep in mind
that Br2O is very unstable, decomposing at -50C, so a hypobromite would be easily decomposed causing liberation of Br2.
4NaBr + 2Ca(OCl)2 ----> 4NaCl + 2Ca(OBr)2
2Ca(OBr)2 ----> 2CaO + 2Br2 + O2
I weep at the sight of flaming acetic anhydride.
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madscientist
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I went back outside and checked on it. It was solidified, still a deep orange, and dry. I added 1g of CO(NH2)2. After a few seconds, the dry mix began
to fizzle (must be HBr) and lighten in color dramatically.
I weep at the sight of flaming acetic anhydride.
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madscientist
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It is now a wet, gunky mix, that contains solids. It seems that the bromination of the urea has formed some liquid. It could be one of two liquids:
COBr2 or C(N)2 (at least so I believe). I doubt that it's COBr2 because there simply wasn't enough bromine present to convince me that such a product
is likely. Also, COBr2 is volatile - boils somewhere around 59C - the beaker has been sitting uncovered for about thirty minutes and the mass hasn't
dropped.
I weep at the sight of flaming acetic anhydride.
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madscientist
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The mass is still unchanged.
I think this experiment may answer the question of how hypochlorites decompose. It looks like this is how the hypobromite decomposed:
2Ca(OBr)2 ----> 2CaO + 2Br2O
2Br2O ----> 2Br2 + O2
So I think it's safe to assume a parallel reaction for a hypochlorite.
2Ca(OCl)2 ----> 2CaO + 2Cl2O
I weep at the sight of flaming acetic anhydride.
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madscientist
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[QUOTE] It could be one of two liquids: COBr2 or C(N)2[/QUOTE]
I meant to write CO(N)2.
I weep at the sight of flaming acetic anhydride.
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madscientist
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I thought about CO(N)2 and deemed that it couldn't exist. CO(NN)2CO certainly could, however.
The mass of the contents of the reaction beaker went up somewhere around two grams over the night! If CO(NN)2CO formed, perhaps oxidation is occuring,
oxidizing it to a peroxide! Either way, I dumped the entire reaction results into 200mL of cool water. At first it was milky, but after a few minutes,
tiny, snow-like clumps began to form, and very slowly drift towards the bottom. Eventually a precipitate had settled. I'm filtering it as I type this.
A report of the properties of the filtered solid is to come.
I weep at the sight of flaming acetic anhydride.
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trinitrotoluene
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interesting
This sounds interesting to me because I wanted to chemically isolate Br. Maybe the method of converting NaBr to Ca(OCl)2 and heating to decompose it
yealding Br is the most easy way to go. 2NaBr+Ca(OCl)2>>>>Ca(OBr)2+NaCl then Ca(Obr)2>>>heat>>> CaO+O+Br2 this method of isolating Br sounds
pretty good. Its better then the methos of reacting Cl with NaBr.
TNT
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trinitrotoluene
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I will be doing this experenment as soon as my digital scale comes then I will have the correct weight ratio. Ill post my results as soon as I decide
when to do the experenment.
TNT
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trinitrotoluene
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My results today
Ok 4 days ago I mixed 2.3 grams of Ca(OCl)2 and 3.8 grams of NaBr. Then added some water. It reacted the temerature went up noticeablely then I left
it there for 4 days.After that in the beaker on one side of the mixture its white and the other side where the mixture is slightly deeper it has a
nice orange brown color. So 3 hours ago I took the Ca(OBr)2 mixture put it in a 250ml flask, sealed it with masking tape, and heated it.After that I
can see water vapor condenseing on the wall of the flask and Bromine gas. Then I took it outside to release the gas. After the gas is released I
started to heat it again. This time very little Br gas was given off and all the water had boiled away. I am left with this solid thats mosltly white
with a small amount of yellow, red, brown color. So I took the solid after it cooled and added some water to it. Then it started to bubble a bot after
its all dissolved I took some PH paper, I measured it and got a reading of PH 14. Well I guess thats the Ca(OH)2.
TNT
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madscientist
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I recently tried to distill bromine out of a mix of Ca(OCl)2 and NaBr. I placed 64g of pool chlorine grade Ca(OCl)2 in a flask,
and mixed in 16g NaBr. I proceeded to add about 20mL of water, which apparently was too much. I corked the flask with a rubber stopper, inserted a
bent glass tube (set up for distillation; condensed liquid would dropper out of the tube into another flask). I began heating; soon, the entire mix
liquified (probably simply
everything dissolving in the water), and then proceeded to begin to boil. I immediately uncorked the flask, and cooled it down. For a while, I slowly
drove off water through relatively gentle heating, but the desired orangish-brownish tinge never appeared. Frustrated, I dumped the experiment on the
waste disposal site located on my lawn.
Conclusion: use a very limited amount of water.
I weep at the sight of flaming acetic anhydride.
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trinitrotoluene
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My next experiment What I will do is use as little water as I can, And after I mix the NaBr with Ca(OCl)2 I will put it in a container filled with a
moisture absorbing substance.This should elimaite most of the water I hope.
TNT
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Darkfire
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Why would you need pure bromine, i have thought of a reason to make it yet but id do it by using:
NaBr + H2SO4 --->KHSO4 + HBr
4HBr + MnO2 ---> MnBr2 Br2 + 2H2O + Br2
CTR
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BromicAcid
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I actually use a VERY similiar method for the preparation of bromine. First I dissolve Ca(OCl)2 and my NaBr in water till I get a saturated solution,
then I add HCl.
2Ca(OCl)2 + 2HCl ---> 2CaCl2 + 2H2O + Cl2
2NaBr + Cl2 ---> 2NaCl + Br2
It just does this reaction in the solution so that I don't have to deal with the Cl2 gas, very convienent, bromine evolution starts immediately
when the HCl (aq) is brought into the solution and can become so fast as to make the solution appear to boil (although the Ca(OCl)2 to chlorine
reaction is exothermic so it does get pretty close some times) in this way the hypobromite is no more and the chlorine takes the place of the bromide
resulting in nearly 100% yeild of the bromine after distillation.
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