Tacho
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How to keep elemental bromine?
Bromine is dangerous and escapes from every container as a gas.
If I keep it mixed with some solvent, like DCM or GAA, will it behave better?
If it does, whats the logic behind it? Why would he "fume" less in a solvent? Some bond to the solvent?
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chemoleo
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Isn't it kept under water, ordinarily? Just to avoid that particular problem?
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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Quantum
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Never used bromine but
I think if you put a less dense liquid on top of it the weight would help compress the bromine and help keep it in liquid form. If it didn't work
at least you would not get a pressure explosion.
Edit: Chemleo posted while I was typing. I was thinking water or possibly some light, non reactive oil as well.
[Edited on 8-4-2004 by Quantum]
What if, what is isn\'t true?
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Tacho
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Thanks.
Well, I have made some bromine oxidating aquous NaBr.
Even after some bromine has precipitated to a brown layer the solution still fumes a lot.
Freezing is not an option since I may find some oposition to keep a volatile poison where we store food. Even considering the antiseptic advantages.
If only it formed some bond to a solvent, like HCl to water.
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Nick F
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I don't have any myself, but once used it at school. It was in a glass bottle with a screw-on plastic lid, probably made of teflon so that it
wasn't corroded.
I guess a glass bottle with ground glass stopper would work too, with a little teflon grease on the stopper.
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chemoleo
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Well, I wouldn't keep the bromine under some type of oil, it tends to react (isn't that a reaction activated by light) by forming
bromo-alkanes etc.
Under water, bromine does of course react to a small extent, according to Br2+H2O--> HBr + HOBr (hypobromic acid). However, as soon as you have
reached equilibrium, the Br2 should not react any further.
I'd stick to Nicks advice, use a glass-stoppered bottle, and keep in a dark place or use brown bottles instead.
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BromicAcid
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I've tried a few ways to keep bromine, in an organic solvent (chloroform) in a glass bottle with a ground glass joint, it slowly reacted with it
and evaporated away anyways. Under water in the same bottle and it evaporated away. And finally in a screw top bottle with no adulterants. The
screw top bottle proved best, just don't heat it with the lid on and the pressure should not get too excessive.
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Geomancer
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I have had problems with HDPE and iodine, the iodine just goes right through the stuff. What is your cap made of, and how much bromine comes through?
Interesting that the ground glass didn't work.
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BromicAcid
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The bromine had, on several occasions, developed internal pressure sufficent to eject the glass stopper. My caps are screw top PTFE lined and very
resistant to the halogen in question.
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Esplosivo
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I posses only very small quantities of bromine but those who store it in somewhat large quantities store it dissolve in some organic solvent such as
CCl4 (1,1,1,1-tetrachloromethane) - which is highly toxic and quite volatile, but inert to bromine.
Theory guides, experiment decides.
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fritz
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I wuold suggest the storage in some kind of an ampoule (may be self-made out of a test-tube) You fill many of these with small amounts of Br2, close
the opening with a burner and store them in the refrigerator. So you avoid the problem with the volatility. If you need some Br2 all you have to do is
take the ampoule out of the refrigerator and put it in some kind of cold-bath to reduce the pressure in the ampoule (the ampoule must be really cold,
to avoid the formation of large amounts of gaseous (=pressure!) Br2) and open it with a file or something else.
The vapour-pressure of Br2 at -25degC;-8degC is 10mmHg;40mmHg compared with water which has those pressures at 11,3degC; 34,1degC
to create good cold-mixtures you may use this recipes
30,2g CaCl2 + 100g ice -> temp.: -50degC
45g CaCl2*6H2O + 100g water -> temp.: -22degC
this should be cold enough for cooling the ampoules
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Marvin
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Using an ampule is a good idea, cooling will not be needed during storage, pressure will not be a problem. Just so long as the neck is thin enough to
be flame sealed quickly.
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Mephisto
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I have the same problem with diethylether. At first I only thought, that the bottle in which I bought it was leaky. However, meanwhile I tried out
many different bottles (also with glass stoppers), nevertheless a sweetish smell of ether still escapes. At university there is a special stainless
steel canister used for storage the ether, however in the cupboard in which it stands the smell is also very strong.
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I am a fish
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| Quote: | Originally posted by Esplosivo
CCl4 (1,1,1,1-tetrachloromethane) |
I've seen a lot of unnecessarily precise nomenclature in my time, but this really takes the biscuit. 
[Edited on 9-4-2004 by I am a fish]
1f `/0u (4|\\| |234d 7|-|15, `/0u |234||`/ |\\|33d 70 937 0u7 /\\/\\0|23.
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a_bab
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My bromine is stored in a special bottle, actually an ordinary bottle with a special stopper. The bromine is Merk made, so the stopper is fine. The
stopper is made (I guess) from ebonite with an opercule of some kind of teflon, since is totally inert to the bromine. There is no presure developped
aswell, when I open the bottle.
I know that bromine is very volatile (boils at 58 degrees C or something), but I don't think it creates a vapor presure as the ether. Ether does
make pressure and is quite dangerous, as the bottle may be blasted if the temperature goes to high (over 35 °C)
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Tacho
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Thank you all,
I'll go for the ampoule idea. I think I know where to buy virgin ampoules. Sealing of small amounts with a flame should not pose a problem if
they are cooled.
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BromicAcid
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I had a bottle in the back of my chemistry supply area, glass with a PTFE cap. When I touched it it left a red sticky film on me, the whole lid
swelled off the top of the container and attacked everything around it. Crazy ol' bromine.
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Theoretic
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You could use a layer of strong CaCl2 or NaCl solution on top, the salt is there to stop the bromine from dissolving (chlorine is much less soluble in
strong NaCl solution than in water, it's even collected over it, could work for bromine also)
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