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Thread: Chemistry lesson - Stink Bombs !

  1. #1
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    Talking Chemistry lesson - Stink Bombs !

    Hi all

    My teenage daughter has developed an unhealthy interest in how to make stink bombs. I'm sure she's has some ulterior motive for this as chemistry is not usually her thing.

    However, it's got me interested and I seem to remember that hydrogen sulphide was used mainly for this purpose, this was created by mixing a weak solution of sulphuric acid with iron filings. I had some of these 'ingredients' lying around and thus set to work. The reaction worked fine but the hydrogen sulphide gas produced wasn't particularly smelly, not as I seem to remember it from my schooldays. I used a 10% sulphuric solution (watered down from my 98% I keep in stock for making EDTA holography plate bleach)

    The other method I remember was to cut the heads off safety matches and mix these with ammonia, thus creating a reaction with the sulphur in the match heads and the ammonia = ammonium sulphide gas. Sadly I haven't got any ammonia lying around the place so I am unable to test this and verify its smelliness.

    Do any of you chemistry buffs remember how to make the very best stink bombs (bad egg smell) as it's well over 30 years since I did this at school.

    Cheers

    Jem
    Quote: "There is a theory which states that if ever, for any reason, anyone discovers what exactly the Universe is for and why it is here it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another that states that this has already happened.... Douglas Adams 1952 - 2001

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    My last one. Not for sale...
    Last edited by decix; 10-25-2008 at 23:15.

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    Ahh Haaa...

    I see on the box that it states 'contains ammonia'. This suggests that ammonia was used in the compound and I therefore deduct that the gas produced may be ammonium sulphide

    Anyone care to expand??

    I like the little 'vials' of fluid. I seem to remember them as being more 'round' in my day.

    Thanks for posting the photo.

    Jem
    Quote: "There is a theory which states that if ever, for any reason, anyone discovers what exactly the Universe is for and why it is here it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another that states that this has already happened.... Douglas Adams 1952 - 2001

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    The best stink bombs are probably made using thiols (they are like alcohols, but with sulfur instead of oxygen). They are incredibly smelly and an attempt to synthesize these will likely cause your whole neighbourhood to be evacuated. They also have higher boiling points than hydrogen sulfide which will make the smell hang around for quite some time.

    Their synthesis is not entirely trivial however (perhaps luckily?). Industrially they are made by reacting an alcohol or alkene with hydrogen sulfide at high pressure (30-35 bar) and moderate temperature (700K). There are probably methods better suited for the small scale, but it is doubtful that you want to synthesize them at all.

    Regarding ammonium sulfide, the smell is still that of hydrogen sulfide (perhaps with a touch of ammonia, which is also very smelly). The ammonia is just a trick to increase the solubility of hydrogen sulfide.

    I will post more on the subject later.

  5. #5
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    Quote Originally Posted by tocket View Post
    I will post more on the subject later.
    Thanks, i'll look forward to that as I find this extremely interesting. It takes me back to my schooldays and our whacky Chemistry teacher

    Cheers

    Jem
    Quote: "There is a theory which states that if ever, for any reason, anyone discovers what exactly the Universe is for and why it is here it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another that states that this has already happened.... Douglas Adams 1952 - 2001

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    Quote Originally Posted by Jem View Post
    this was created by mixing a weak solution of sulphuric acid with iron filings. I had some of these 'ingredients' lying around and thus set to work. The reaction worked fine but the hydrogen sulphide gas produced wasn't particularly smelly, not as I seem to remember it from my schooldays.
    That's probably because whatever little hydrogen sulfide evolved comes from impurities in the iron; the main component of the gas is hydrogen which is smell and tasteless. Pure iron does not give any hydrogen sulfide. If you want to make hydrogen sulfide you should instead use a metal sulfide like zinc or iron sulfide.

    The other method I remember was to cut the heads off safety matches and mix these with ammonia, thus creating a reaction with the sulphur in the match heads and the ammonia = ammonium sulphide gas. Sadly I haven't got any ammonia lying around the place so I am unable to test this and verify its smelliness.
    I don't see how ammonia would react with sulfur except under harsh conditions where ammonium polysulfides could be formed. A more plausible route to hydrogen sulfide from matches is mixing them with acid as some match heads contain antimony sulfide, though this is potentially very dangerous as it would yield a mixture of the highly flammable hydrogen sulfide and chlorine dioxide (which is considerably more reactive than oxygen). Generally, combustible material + chlorine dioxide = nasty fire.

    Since you're looking for that rotten egg smell hydrogen sulfide is the way to go, but because it is a gas you need to either absorb it in something (aqueous ammonia for example) or generate it in situ. The latter is probably preferable if you are going to prepare the stink bombs yourself, because it doesn't involve stinking your house down as the absorption procedure likely would. That, and it's fairly easy. All you need is a vessel containing a metal sulfide and acid separated by some sort of shock sensitive divider. When the two substances mix they will instantly start to react, forming hydrogen sulfide. The rate of reaction can be varied by choice of metal sulfide, particle size, acid and concentration, etc.

    One important consideration is that hydrogen sulfide is toxic (comparable to hydrogen cyanide). While the perception threshold is several thousand times lower than the toxic concentration it is important to know that exposure to high concentrations of hydrogen sulfide will cause you to (temporarily) lose your sense of smell in a matter of seconds. Therefore it is easy to underestimate the extent of your exposure. Only work with hydrogen sulfide in very well ventilated environments (fume hood/outdoor).

    Now, if you're interested in other nasty smells than rotten eggs there are plenty with substances out there with not-so-pleasant smells. For example:
    Methanethiol - rotten cabbage
    Cadaverine and putrescine - guess
    Skatole - guess
    Pyridine - fishy
    Diethyl sulfide - garlic-like

    Funnily enough skatole is used in perfumes...

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    I would just order the foil package type stink bombs online, they are cheap - like 25 cents a piece. I haven't seen those glass vial type stink bombs for quite some time, but then again I haven't been at the neighborhood joke shop for a while either :P

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    Thanks for the chemisrty lesson Tocket

    It's at times like this that I wish I had taken much more notice of what we were being taught in chemistry. It's strange but sometimes it takes many years to realise how good the teachers really were and how we benefitted from a lack of health and safety rules.

    I've had this conversation in another thread, but todays teaching of science is mainly theory which fails to stimulate the kids as they don't get 'hands on' experience. What they need is explosions, big bangs, bright flashes and smells

    Cheers

    Jem
    Quote: "There is a theory which states that if ever, for any reason, anyone discovers what exactly the Universe is for and why it is here it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another that states that this has already happened.... Douglas Adams 1952 - 2001

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    RE the Toket's comment of being careful with Hydrogen Sulfide...
    Here in Rotorua New Zealand we live in a collapsed caldera (old volcano basically)..

    Over the years we have had quite a number of fatalities with this gas. Anywhere here below ground level such as culverts etc are potentially very dangerous.
    We had a very sad case where a honeymoon couple died in a motel on their wedding night due to poorly maintained vents.

    One of the dangers here is the subtle nature of this .. by the time you may realise (if in fact you do) you may be already out to it and the grim reaper is waiting.

    Not sure how dangerous the "bottled version" is (maybe Toket can tell us) however may pay to be very careful with this gas based on experiences here.

    Good luck don't kill yourself

    Ray
    NZ

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    Quote Originally Posted by Pitts View Post
    Here in Rotorua New Zealand we live in a collapsed caldera
    I wasn't planning on making a volcano's worth of the stuff just a small amount in a test tube to demo it to my daughter

    NZ, more especially Rotorua is on my to do list in the next couple of years. We have some friends live in Wangerai and hope to visit them. I'll remember to bring my gas mask

    Cheers

    Jem
    Quote: "There is a theory which states that if ever, for any reason, anyone discovers what exactly the Universe is for and why it is here it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another that states that this has already happened.... Douglas Adams 1952 - 2001

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