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elementcollector1
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Got it, thanks.
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watson.fawkes
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Quote: Originally posted by Endimion17  | | I recommend downloading one of several available flameworking (not glassblowing, that's just "making bottles") manuals on the Web.
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Please tell that to the ASGS, the American Scientific Glassblowing Society, and the BSSG, the British
Society of Scientific Glassblowers. Also to the Scientific Glassblowing Learning Center, one of the best web sites with instructional material.
If you're doing keyword searches, use "scientific glassblowing". You'll get more hits.
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elementcollector1
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Been a while since I found this topic (necromancy powers activate!), but I just got most of my distillation apparatus today. I still have a few
questions:
-From what I've heard, bromine tends to somehow get 'trapped' in glassware. If this becomes a problem, how do I get rid of it?
-How long should my condenser be for the most effective distillation? (Standard, non-coiled Liebig).
-How fast does the bromine eat through the rubber of the corks? (I couldn't find ground-glass.)
When I get the whole distillation setup done, I'll try to get pics and weight of the yield.
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plante1999
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I recommend to use ground glass since rubber is not completely destroyed but some oil will be in your bromine.
Sodium thiosulphate sol. will reduce bromine to bromide which is water soluble.
I never asked for this.
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elementcollector1
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Where do I get sodium thiosulfate?
So, is there a good length for my condenser to be, or will any length do?
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woelen
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Bromine distillation requires fairly good cooling of your condenser, otherwise too much will escape as vapor. Remember, bromine is very volatile and
air-cooling most likely will be insufficient, except maybe on cold days. You certainly will collect some bromine, but having a loss of a few tens of
percent is not pleasant at all, especially in a confined space.
If you do not have ground glass, then you can use rubber stoppers and that kind of things, but you have to wrap all these things in a fairly thick
layer of white teflon tape, which is used in plumbing. This tape will absorb some bromine and become brown, but it does not fall apart and it does not
give off grease or oil. Unprotected rubber or cork is a no go with bromine. It will lead to a lot of contamination of your bromine. It reacts with
bromine, giving all kinds of (somewhat) volatile organics, which leach into your bromine.
[Edited on 18-6-12 by woelen]
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Zan Divine
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I just bought a pound on e-bay for $10 delivered.
He who makes a beast of himself gets rid of some of the pain of being a man. --HST
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elementcollector1
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Sorry to revive this old thing, but I attempted distillation of bromine today with no success. Then, I had another idea: Since bromine was heavier
than air, I could trap the bromine-water in a large flask, boil the flask, then 'pour' the bromine into something cold to condense it. Would this
work?
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Endimion17
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| Quote: Originally posted by elementcollector1 | | Sorry to revive this old thing, but I attempted distillation of bromine today with no success. Then, I had another idea: Since bromine was heavier
than air, I could trap the bromine-water in a large flask, boil the flask, then 'pour' the bromine into something cold to condense it. Would this
work? |
No. The smaller the distilling system and the more efficient the cooling system, the better the yield.
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cal
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Bromine Systhesis
http://www.youtube.com/watch?v=OB4MmPTOBxg, Elemental Bromine
| Quote: Originally posted by longtermmadscientist | I've been thinking of a simple way of producing a few ml of elemental bromine using sodium bromide. Could conc. HNO3 be used on NaBr solid or
solution? I've been researching up on this, and there's a lot of talk of H2SO4 but it seems it's not a strong enough oxidant to produce Br2 in good
yield, and you get a lot of HBr.
My concern is that I will produce a lot of NO2, which, being the same colour as Br2, could lead to some confusion as to how much Br2 has been
produced. Also, I'd like to know whether the bromine would contain more that a trace of NO2. Water impurity can be extracted by conc. H2SO4, but what
about removing the NO2, if this turns out to be an issue? |
[Edited on 13-8-2012 by cal]
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elementcollector1
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I don't have much apparatus to bubble chlorine through water... and even if I did, my distillation setup doesn't work well. I'm thinking of getting
ground glass stuff from united nuclear, but does anyone have cheaper sources for the entire kit?
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MrHomeScientist
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Dr. Bob, here on this forum, has a huge stock of glassware for sale. I've bought from him 3 or 4 times and he's given me tons of goodies. Get in touch
with him for some great deals - last I heard he was running low on full distillation kits though! 24/40 is the size I like to use, but if you're
focusing on small scale bromine production you might want to go smaller.
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elementcollector1
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Working out a deal as we speak... Somewhat fittingly, he only has a smaller kit, 14/20. Worth it!
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Pyro
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it seems like everybody is taking the H2SO4+NaBr method, isn't it a LOT more effective to just replace the Br- with Cl- by simply bubbling Cl2
through it?
all above information is intellectual property of Pyro.  |
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elementcollector1
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That's what I'm going to try next. The problem with the Cl2 method is that it seems to form interhalogens between chlorine and bromine (BrCl, for
instance).
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Pyro
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but why does this guy do it like that: http://www.youtube.com/watch?v=OB4MmPTOBxg
he prefers this to the NaBr+H2SO4, i will just use NaBr instead of KBr for the chlorine method.
anyway, wouldn't almost all the Cl2 react with the NaBr before reacting with the Br2
all above information is intellectual property of Pyro. |
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elementcollector1
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That is correct, and he did mention "that if one smells the slightest hint of chlorine, the reaction is done". I would think that if you continued
adding chlorine, the bromine would only then begin reacting (as the chlorine has little to nothing else to react with) to make interhalogens.
Any soluble bromide works as long as you use all ground-glass apparatus, a saturated solution, and a necessary amount of caution.
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Pyro
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to rid Br2 of BrCl just keep it in a beaker at about 10*C and the BrCl will evaporate first.
all above information is intellectual property of Pyro. |
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elementcollector1
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Good to know! Incidentally, I wonder if one could collect an interhalogen through a similar method to study its properties?
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woelen
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The method of bubbling chlorine through a solution of NaBr or KBr can be done, but for best results, you have to bubble just enough chlorine through
the solution that all bromide is converted to bromine. Besides that, you still need a distillation setup to get all dissolved bromine out of the
water.
If you don't have a means to do a distillation, then the BaBr/chlorine method is not easy at all. As long as you don't bubble enough Cl2 through the
solution, hardly and Br2 separates from the liquid. Br2 dissolves in a solution of a bromide quite well, it forms a complex ion Br3(-), very similar
to the I3(-) ion, known from iodine. This Br3(-) ion is more labile than I3(-) and hence, with a distillation setup you can break this ion and drive
the bromine out of solution, but if you don't have a distillation setup and intend to pipette the Br2 from below the aqueous layer, then your losses
will be huge.
Bubbling too much chlorine is equally bad. You get BrCl, but even worse, part of the bromine is lost as bromic acid. BrCl reacts with water, giving
bromic acid, chloride ion and bromine.
Another issue is that when you bubble chlorine through a solution of NaBr not all chlorine reacts, some may make it to the surface and escape, giving
Cl2-gas and BrCl-vapor above the aqueous layer. You need to disperse the Cl2-gas into very small bubbles.
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Pyro
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i got a distillation setup, and isn't using Cl2 still more effective than the H2SO4+NaBr method?
how are yeilds for that method?
all above information is intellectual property of Pyro. |
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vmelkon
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| Quote: Originally posted by Pyro | i got a distillation setup, and isn't using Cl2 still more effective than the H2SO4+NaBr method?
how are yeilds for that method? |
According to myst32YT, it is more efficient to bubble Cl2 through NaBr solution.
I think it makes sense because the H2SO4+NaBr would probably waste some Bromine as HBr gas.
Both methods are going to produce contaminated bromine.
The ultimate method is electrolysis. Get PbBr2, melt it, electrolyze using a couple of graphite electrodes. This method was used to demonstrate
element production in classes. Then it got replaced by ZnCl2.
Perhaps you can try ZnBr2?
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elementcollector1
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True, but for us amateurs, it's already hard enough to distill bromine from a chemical mix, so while the bromine from the molten bromide would be very
pure, how on earth would one get it out of there, keeping in mind that we don't have expensive equipment (at least, MOST of us don't)?
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vmelkon
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It doesn't require expensive equipment. You need a heat resistant ceramic dish. Perhaps some of us don't have one (I don't). I would use a metal can
(the sawed off bottom of a propane can).
The melting point of ZnBr2 is only 394 °C. I would use propane torch.
Now for the important part. To capture the bromine gas, you need glass tubing and the graphite anode needs to be inside it. This is something that I
have made myself in order to capture iodine vapors.
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elementcollector1
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...Can we see your custom apparatus?
Also, one would need to lead the bromine away from the reaction into a suitable cooling vessel, as the bromine would definitely come out gaseous at
400 C.
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