DrMario
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THIOUREA - odorless or fart-scented?
Serious question, actually: I had the "pleasure" of smelling the air around a bottle of thioiurea after the lid has been removed. I don't know how old
this bottle is - chances are, several years. It's so godawfully smelly when you open the lid, there is no need to even put your nose near it - several
cubic meters of air become infested with fart-like odor. Yes, it does resemble SH2 very much.
However, according to the Wikipedia entry for thiourea, the compound should be odorless.
Any idea what's going on here? Did the thiol form of thiourea decompose during the years to form SH2?
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DrMario
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In spite of the humorous framing of it, this is a serious question.
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UnintentionalChaos
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I would be extremely unsurprised by the decomposition of thiourea to urea and hydrogen sulfide given time and water content.
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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Nicodem
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Thread Moved
1-10-2014 at 22:22 |
DrMario
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Granted, that's what I would assume as well, but am very confused by Wikipedia's assertion that it's "odorless".
BTW, I have the bottle next to my desk right now (temporarily).
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DrMario
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The only iron salt I have at home is FeCl3 - will H2S precipitate FeS if H2S is bubbled through a FeCl3 solution? I would expect yes. I just want to
easily determine whether this gas is really H2S.
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Dr.Bob
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Your bottle of thiourea may have been from any of many sources or manufacturers, thus, it is hard to tell what might be in it. If made in China, it
is likely that it is not very pure, based on my experience, so there is a high likelihood that is has traces of other sulfur chemicals in it, but
given that thiourea is made with H2S, the chances of traces of it remaining in the final product are high, perhaps even trapped in the crystal
structure, so it will slowly leak out for years. I would also guess that water will form H2S with it at some rate, and it does not take much. Look
up a purification in the book "Purification of common lab chemicals" if you want to recrystallize it to reduce the problem.
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DrMario
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Quote: Originally posted by Dr.Bob  | | Your bottle of thiourea may have been from any of many sources or manufacturers, thus, it is hard to tell what might be in it. If made in China, it
is likely that it is not very pure, based on my experience, so there is a high likelihood that is has traces of other sulfur chemicals in it, but
given that thiourea is made with H2S, the chances of traces of it remaining in the final product are high, perhaps even trapped in the crystal
structure, so it will slowly leak out for years. I would also guess that water will form H2S with it at some rate, and it does not take much.
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OK, yes, that makes sense.
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mnick12
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DrMario,
I have had a similar experience with my bottle of thiourea, when I open the bottle it smells like a rhino fart for a few seconds. However I have
noticed that the crystals themselves do not smell to bad, just when I open the bottle. One thing I would say it doesnt really smell like H2S to me,
more like beta-mercaptoethanol, if anyone has ever worked in a bio lab. I wonder if it is really H2S or something else.
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DraconicAcid
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I've not used thiourea, but I've used carbon disulphide. It's odorless when pure, but it's never pure unless you've freshly distilled it.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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DrMario
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| Quote: Originally posted by mnick12 | DrMario,
I have had a similar experience with my bottle of thiourea, when I open the bottle it smells like a rhino fart for a few seconds. However I have
noticed that the crystals themselves do not smell to bad, just when I open the bottle. One thing I would say it doesnt really smell like H2S to me,
more like beta-mercaptoethanol, if anyone has ever worked in a bio lab. I wonder if it is really H2S or something else. |
I am not sure it is H2S, at all - that's why I'll try to analyze it sometimes soon, with an iron salt (hopefully FeCl3 will do).
Good call on rhino fart 
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