chemrox
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sealing a Br sample
I want to donate a small q of Br to a member. I'd like a suggestion on how to seal this up in a small test tube. I haven't done more than seal and
bend glass tubing in quite awhile. Br is so damned volatile I worry about splashing during the seal and I don't like open flame in my hood. That's why
I have a bucket of sand under it.
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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aga
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Lots of Protective gear and bravery (in that order) is the solution.
Experience can only be had by Doing.
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gdflp
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I actually haven't had too many issues dealing bromine ampoules. I would recommend using a much larger container than is necessary to allow for a
larger gap between the heated glass and bromine. This minimizes the change in temperature of the bromine during the sealing, and thus prevents issues
associated with a higher pressure inside the ampoule than out due to bromine vaporizing. Do realize that sending bromine is likely illegal regardless
of the method you use.
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Heavy Walter
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Hi
Cooling the filled ampoule would help.
Ice-acetone or dry ice and blowing a low flow of N2 or Ar through a needle in order to keep the Br under inert atmosphere.
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Volanschemia
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Get the test tube (without anything in it) and heat it about 1/4 of the way down from the top until it is soft.
Using a pair of pliers, pull the top of the test tube (don't twist it) until you have a narrow section in the middle about 3mm wide.
Remove the heat and let it cool in that position. It should look a bit like this.
Add the Bromine to the test tube through the narrow neck using a pasteur pipette so you don't get any Br2 on the walls of the narrow
portion. Don't fill it any more than 1cm from the bottom of the narrow part.
Get the torch again and heat the middle of the narrow portion until soft.
Using the pliers, pull it out while giving it a small twist. Tidy up the end with the torch a little if you want, but don't spend too long on it or
the glass will bubble out.
[Edited on 18-3-2016 by Volanschemia]
"The chemists are a strange class of mortals, impelled by an almost insane impulse to seek their pleasures amid smoke and
vapor, soot and flame, poisons and poverty; yet among all these evils I seem to live so sweetly that may I die if I were to change places with the
Persian king" - Johann Joachim Becher, 1635 to 1682.
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woelen
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Before you ship the bromine, be sure that the ampoule made from the test tube is really stable. I used exactly this method of drawing the test tube
thinner and thinner until it makes a seal. For some samples you indeed first have to let it cool down, for others (such as larger metal lumps in the
bottom of the test tube) you first put the sample in the tube and then seal it in one go.
This proces gives very nice looking samples, but unfortunately quite frequently the ampoule spontaneously cracks even when it is just put aside and
not touched at all. This can happen days after the ampoule is made. Apparently there can be some strain in the glass and this can lead to cracks at
random times. See this other thread which I started:
http://www.sciencemadness.org/talk/viewthread.php?tid=65525
So, be absolutely sure that the ampoule is stable. In transport there will be extra stress on the ampoule and if it already can crack while just put
aside, then in transport it certainly will crack.
I myself would use a small bottle for sending the bromine, with a PTFE-lined cap and wrapped in a plastic bag, in which also some Na2CO3, Na2S2O3 is
put in order to absorb smell of bromine.
You should be aware though that sending bromine may be illegal, or at least requires special labelling (for small amounts up to 25 grams or so there
may be exceptions, with suitable methods of packaging and labelling). Lookup what can be done legally.
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alking
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Afaik, and do your research first, but outside of scheduled compounds it is legal in the US to mail amounts <30ml/30g without a hazmat courier.
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