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Author: Subject: red CaBr2 ???
YT2095
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[*] posted on 3-7-2008 at 00:23
red CaBr2 ???


I`v encountered a very strange thing whilst exerimenting to make Calcium Bromide in a slow controlled way, here`s the basic setup:



in effect the Br2 gas passes over slowly into the next tube, and since it`s heavy it will fall to the Calcium and then react.

but surely the result should be a White product and not this:



now granted the Ca metal had an oxide layer on it and that`s quite visible also, but even with that oxide it should react and form a white product too.

any idea what`s happening here?




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[*] posted on 3-7-2008 at 01:49


Your product contains quite some tribromide ion, Br3(-). If you bring bromine in contact with bromide, then this complex is formed. With sodium bromide, potassium bromide and apparently also with your CaBr2, some of this ion is formed. With the heavier metals, such as Rb and Cs, you can make this compound even in a pure state, e.g. CsBr3.

You can easily get rid of this bromine. Take the red material and put it in a test tube and heat this test tube. The Br2 will be expelled from the solid.




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YT2095
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[*] posted on 3-7-2008 at 02:47


aha, Thank You ;)

I think I may try and isolate this as it is rather than decompose it, I have a few grams of old calcium metal granules that I want to get rid of before opening a new container and didn`t want to use it all drying alcohol.
there isn`t much writen on the net that I can find about calcium tribromide, it all seems to be about Phosphorus sadly.




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