BromicAcid - 7-5-2006 at 16:27
I store my bromine in a glass bottle with a ground glass stopper. It is stored under water and was never distilled, simply pipetted from the bottom
of the container it was formed in and put into the bottle. The stopper of the bottle is wrapped in Teflon tape in such a way as to hold it on if the
pressure in the bottle becomes noticeable, prior to me doing this the stopper would occasionally pop off.
Today when I was removing the Teflon tape I noticed crystals all over the tape and it is getting somewhat brittle. Some bromine usually leaks from
the ground glass at a slow rate so the tape is usually exposed to bromine gas. I have noticed these crystals before on several occasions but finally
decided to make a post on it.
These crystals though are somewhat abundant. I don't think they are from some other source in my shed, the crystals are not on anything else in the
shed and I store no ammonia or other bases in there that might take flight and react with bromine being released. The crystals are clear and
water-soluble
I doubt they are from the reaction between the Teflon and the bromine but that is the first thing that crossed my mind. Any thoughts on this?
enhzflep - 7-5-2006 at 23:25
Without knowing the reaction that you use to produce you Bromine, it is a little hard to say. However I noted in the following MSDS for Teflon Tape,
that it is "incompatible with Interhalogen Compounds"
http://www.imscompany.com/msds/105579.pdf
If, you form your bromine from Chlorine gas and Pottasium/Sodium Bromide salt, then it is certainly possible that your product contains some BrCl.
I have no real experience with any of these 4 materials however, and as such have no ability to predict the effect of BrCl on Teflon tape. Hope this
helps.
garage chemist - 8-5-2006 at 07:01
Pure teflon will not react with bromine. I have a several years old bromine bottle with teflon gasket and it is perfectly intact.
However, the teflon tape might contain softeners. Pure teflon is really stiff and not flexible.
After all, the teflon tape is meant for making screw connections tight, not for resisting chemicals.
gsd - 8-5-2006 at 07:38
I do not know the source of your Bromine, but considerable part of Bromine available industrially is recycled. which means it is not extracted from
bitterns of Sea-water but from effluent streams of bromination reactions. ( Afterall in most bromination processes only half of Br2 is gainfully
utilized while the other half goes waste in the form of HBr etc.) My experience is this Bromine contains impurities of parent organic molecules which
are very difficult to remove by simple distillation. In all probability the crystals which you have observed are of these organic impurities.
BromicAcid - 8-5-2006 at 14:21
My bromine was produced from the reaction between sodium bromide, sodium bromate, and sulfuric acid with the formed bromine sucked out from the bottom
so no other halogens were present. Most definately likely some kind of sofener or something in the tape that I used though.
woelen - 8-5-2006 at 22:38
I also can imagine that some HBr was/is present in the bromine and the aqueous layer above it. HBr has the same effect as HCl and bottles, which have
HBr in them become 'frosted' near the cap and eventually, even crystals can be formed. I also have a bottle with some bromine in it (without the water
layer), and I see no signs of crystals near the cap, only that the cap becomes brown.
unionised - 9-5-2006 at 12:28
This thread reminds me of this one
http://www.sciencemadness.org/talk/viewthread.php?tid=5740