draculic acid69
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Tech grade NaBr smells
So I just baked some NaBr in the oven to dehydrate it for an accurate weight measurement and upon removing from the oven I realized that it had a
rubbery
(at first) seaweed rotten egg smell coming from it.i now fear there's a (hopefully) small amount of sodium sulfide like impurity and I'm wondering if
washing this with a small amount of vinegar outside to liberate the h2s then washing this with acetone to get rid of the vinegar will remove all
sulfur compounds?
I intend to make bromine with this via kmno4 and h2so4 but don't like the idea of h2s formation as I'm shit scared of it and don't know how it Will
affect everything down the road.is sulfide salts a common impurity in tech grade NaBr?is there a way to test how many% of this is in it? And how will
a sodium acetate impurity affect an oxidation reaction like this? This smells without adding any acid so I guess it's enough in there to be noticeable
from just atmospheric co2 and moisture acidifying it.
[Edited on 30-12-2019 by draculic acid69]
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j_sum1
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Seems odd. But assuming it is a sulfide impurity, that sound like an ok process for cleaning it up. Not really sure how necessary it is in your
application but it may hurt your yield.
Obviously be cautious with H2S. But it is not something to be petrified of.
It smells fart-like at low concentrations around 5ppm which is not enough to do damage. By 20ppm it becomes quite umpleasant. The real danger is that
it becomes odourless at higher concentrations where it is actually quite toxic.
So, a little whiff won't kill you. Use a scrubber. Work outside with a good breeze or a fan. If it starts to smell really bad then vacate.
You can make test strips using Cu2+ salts. Copper sulfide is black and alerts you to the presence of H2S if ypu feel you need it.
Copper sulfate solution makes a good second scrubber too. A colour change lets you know if anything escapes the first.
[edit]
I misremembered my concentrations.
5ppm will smell worse than a fart. If you experienced this you would find it quite unpleasant.
20-50ppm is sufficient to cause eye and respiratory irritation.
500ppm and you are approaching deadly concentrations. According to Wikipedia the lowest published LD for 30 min exposure is 600ppm.
People in Rotorua (population 60000) live their lives around this stuff: median exposure is reported at 20ppb but short term exposure can be much much
higher: often hundreds of ppb. 20ppb is within the smell threshold. 60ppb would smell quite eggy. I believe that odour desensitisation occurs around
50ppm(1000 times greater than eggyness). The bottom line is that if you can smell it but are not irritated by it and have taken sensible precautions
then you can be confident that the concentration is sufficiently low as to not cause harm.
[Edited on 31-12-2019 by j_sum1]
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Pumukli
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Are you sure you smelled H2S?
What if the cause of the smell is Br2 in low conc? (Bromos means "stinky" in greek, if memory serves me well.) 
On the other hand what problems could cause some H2S in your planned bromine synth? I think nothing! It would instantly oxidized to
sulphate by either permanganate or elemental bromine in that acidic environment! Just check the fate of sulfide in acide when mixed with these
oxidizers (permanganate, halogens)!
Why introduce another uncertainty (acetate)?
Not to downplay the danger of H2S but I can tell you that eons ago we were "playing" with this gas in the class room, not even in the fume hood,
liberated in a Kipp-aparatus and bubbled in test tubes in order to precipitate various metal ions... We had to open the windows of course, the stench
was awful, but everybody survived. We were breathing this contaminated air for
a good 20-30 minutes, until the experiment lasted. When we were released to breathe fresh air, we immediately recovered. So yes, H2S is bad and
deadly, but "screams" danger by its unbearable stench and it is a good thing.
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draculic acid69
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Pretty sure it was h2s.the chance of any free bromine I'm guessing is pretty low as there's no discoloration of the salts or odor until heated and
it's 3+yr old packaging is still in one piece.as for an acetate impurity I might just use soda water if this is acidic enough to liberate h2s.im
guessing that it is and will leave carbonate that will instantly react with h2so4 to leave sulfate.im just worried about the concentration though.
.00x% is bearable but 3% would certainly be a smelly detectable amount I don't want to deal with atm.
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Bedlasky
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I have 1kg of KBr in home and it have weird nusty smell which I suppose is bromine. KBr is white, no evident discoloration, but it's only reasonable
explanation for me. Maybe it's the same with your NaBr. Sulfide contamination in bromide would be unlikely. In my opinion heating NaBr in the presence
of air lead to formation of very small amount of bromine which give your bromide this smell.
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woelen
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I never heard of NaBr with sulfide impurity. Very strange.
But I would not worry any H2S (if it is present). If you make Br2, then you are making an equally dangerous chemical. Handling Br2 requires great care
and you should avoid inhalng it.
NaBr should be odorless. Even when heated strongly (to 250 C or so I tried), it remains odorless, and it remains white. There may be some organic
impurity in your sample, which causes change of color on heating (usually organic contamination leads to yellow, brown, red, or even black colors on
strong heating).
For making bromine I do not expect any issues with your NaBr. If it does, then you must have really impure stuff.
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draculic acid69
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Like I said tech grade of unknown origin.am using it right now.no problem so far.
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draculic acid69
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I did the kmno4, h2so4,nabr method.87g of nabr gave 55.5g of br2.
I still think there's a small sulfide impurity of some sort but it must be
a small amount.
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draculic acid69
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I meant 55.5g br2 from 77g nabr.
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