Sciencemadness Discussion Board

The smell of halogens

sbreheny - 16-7-2014 at 08:16

Hi all,

I'm wondering if there is something strange about my sense of smell :)

For example, elemental Iodine vapor seems to have no smell at all to me. If I waft a tiny amount toward my nose, I smell nothing. If I waft a little bit more, my nose and throat develop a sudden irritation. Don't worry - I know that this is NOT a good thing to do on a regular basis - this was one brief instance.

I do smell Chlorine even at very small concentrations. I have never purposely made chlorine but I am assuming that the strong odor I smell when I use bleach is chlorine gas. It is very sharp and somewhat pleasant/clean smell if very dilute. NO2 also smells similar to Chlorine to me.

Most of the references I've seen say that Bromine smells like Chlorine. To me, there is NO similarity to the smells. Bromine smells a bit like sulfur dioxide or hydrogen sulfide, to me. What do you guys think it smells like?

Once again, with the exception of the Iodine where I purposely wafted a tiny amount of it, all of these cases were incidental, dilute exposure and not intentional sniffing.

Sean

arkoma - 16-7-2014 at 09:02

Chlorine smells "clean" to me also; so does Raid Fly Spray though..................

I can smell Iodine, but can't describe the smell. Never smelled Bromine.

Praxichys - 16-7-2014 at 09:06

For me:

Chlorine smells like, well, chlorine. It's choking and terrible even in low concentrations. Bleach smells like chlorine. HCl smells like chlorine but has a more distinct burning, biting, vomit characteristic.

Bromine smells sort of like chlorine, but also more like vomit. Accidentally brominating your skin makes it reek for days.

Iodine smells almost like metal does, but somehow also somewhat salty. Also unpleasant but it's not nearly as volitile as the other two so it is harder to come across.

I have never had the displeasure of smelling fluorine, and I don't think I want to.

Texium - 16-7-2014 at 09:08

I find that bromine smells to me a bit like a cross between chlorine and iodine. I really like the smell of iodine. It has that nice clean smell without as much of the irritating nature of its counterparts.
Bromine smelling like H2S though... that's rather odd.
They all have somewhat similar characteristics, with the smell becoming sharper and more biting for the lighter ones.

arkoma - 16-7-2014 at 09:27

Quote: Originally posted by Praxichys  
For me:

Chlorine smells like, well, chlorine. It's choking and terrible even in low concentrations. Bleach smells like chlorine. HCl smells like chlorine but has a more distinct burning, biting, vomit characteristic.

Bromine smells sort of like chlorine, but also more like vomit. Accidentally brominating your skin makes it reek for days.

Iodine smells almost like metal does, but somehow also somewhat salty. Also unpleasant but it's not nearly as volitile as the other two so it is harder to come across.

I have never had the displeasure of smelling fluorine, and I don't think I want to.



Interesting. I like the smell of the halogens--no "vomit" note to me at all.

Metacelsus - 16-7-2014 at 09:32

I don't mind bromine too much, but I know people who absolutely hate it.

Has anyone here smelled fluorine?

Motherload - 16-7-2014 at 09:43

Nor should one smell Fluorine.
It is oxidizing enough to ignite steel wool and sulfur at room temp just by contact.

Texium - 16-7-2014 at 09:58

Yeah, I don't think that it's really possible to smell fluorine and live to tell the tale...

woelen - 16-7-2014 at 10:56

Chlorine has a smell, which differs quite a lot from the smell of bleach (at least for me). Just try the following little experiment, which is safe and produces enough chlorine to feel the strong irritation, but not enough to be dangerous. Even in a badly ventilated room this is safe.

Take 2 ml of bleach and smell this.
Add one drop of 10% HCl and then smell again. Note the difference.

I do not dislike the smell of chlorine, as long as it does not become too concentrated.

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Bromine has a smell of chlorine, but it also is somewhat musky and sticks to clothes, curtains and so on. I also do not really dislike the smell of bromine. Bromine is less immediately irritating and burning than chlorine, when inhaled, but after a minute or so, bromine starts burning in your nose and throat.

----------------------------------------

Iodine has quite a different smell to me. It is weaker and less irritating. Again, I do not really dislike the smell of iodine.

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HCl has quite a different smell to me. It is just acrid, sharp and does not really have a smell. The same is true for HBr and HF. To me, they all have about the same smell. This is one of the reasons why I am so afraid of working with HF. If I sense some HCl or HBr, then I do not really worry about it. It is a minor inconvenience to me (as long as the concentration remains low). I feel the same with HF, but the latter is MUCH more dangerous and a strong systemic poison.

Brain&Force - 16-7-2014 at 14:16

Iodine smells like a swimming pool. Absolutely, 100%. All of my friends agree with me on this.

Texium - 16-7-2014 at 15:26

Quote: Originally posted by Brain&Force  
Iodine smells like a swimming pool. Absolutely, 100%. All of my friends agree with me on this.
I don't know, I think it smells too medicinal to be swimming pool smell. Chlorine and bromine are more reminiscent of a swimming pool to me.

UnintentionalChaos - 16-7-2014 at 21:23

Quote: Originally posted by zts16  
Yeah, I don't think that it's really possible to smell fluorine and live to tell the tale...


It is quite possible. http://www.sciencemadness.org/talk/viewthread.php?tid=1216&a...

chornedsnorkack - 17-7-2014 at 05:02

Does elemental fluorine have a distinctive smell, or is it identical to the smell of oxygen difluoride?

Zyklon-A - 17-7-2014 at 14:36

Quote: Originally posted by Brain&Force  
Iodine smells like a swimming pool. Absolutely, 100%. All of my friends agree with me on this.

I agree, but not 100%. It smells quite similar, but not the same.
It should be quite obvious, the smell of a swimming pool comes from tiny amonunts of chlorine, which are liberated from the chlorinating compound used to disinfect the pool. So, it stands to reason, that the only thing that smells exactly like a swimming pool, is chlorine- Minute concentrations of course.
Iodine I like much better, smells cleaner.

Brain&Force - 17-7-2014 at 15:16

Iodine smells a little bit like garlic at very, very low concentrations to me. I do agree that it's not exactly like pool chlorine, but it's by far the closest match.

subsecret - 21-7-2014 at 20:12

Chlorine and NO2 smell very similar. Nitric acid vapors themselves smell a lot like chlorine. In fact, the first time I distilled nitric acid, and had the chance to smell NOx, I thought that chlorine had somehow contaminated the reaction. Very bizarre indeed.

Bromine smells a bit more "heavy" than chlorine. I've never smelled iodine vapors, so I can't compare.

Like woelen said, HCl doesn't really smell like chlorine. It produces a distinctive burning sensation, even at lower concentrations, yet I think that it smells "sweeter" than chlorine.


[Edited on 22-7-2014 by Awesomeness]

MrHomeScientist - 22-7-2014 at 08:11

With fluorine's extreme reactivity, I'd think that smelling fluorine itself would be near impossible. Wouldn't it react with something on its way to your nose, and convert into something like HF?

I smelled HF once, and it was rather terrifying. I was outside, but I still backed away immediately and reassessed my safety procedures. It was produced from ammonium bifluoride being brought into solution. It has a very light halogen-ish smell, but is distinct from the others. Each halogen has a very unique smell. In fact, just about every chemical vapor I've made has its own distinct smell. Nothing really smells identical to anything else, to me.

I have a hard time describing smells. For whatever reason, I tend to associate smells with colors. From 'dark' to 'light' smells, I'd rank it as bromine, iodine, chlorine, HF. Could be I'm just combining their actual colors and smells together in my mind. All are irritating at the right concentrations, though bromine and iodine are quite a bit less so than chlorine.

Chemosynthesis - 22-7-2014 at 09:11

Quote: Originally posted by MrHomeScientist  
With fluorine's extreme reactivity, I'd think that smelling fluorine itself would be near impossible. Wouldn't it react with something on its way to your nose, and convert into something like HF?

Ambient moisture, and if in contact with mucuous mebranes in the nasal passage, I expect the same conversion.
2F2(g) + 2H2O(g) → O2(g) + 4HF(g)
2F2(g) + 2H2O(l) → O2(g) + 4HF(aq)
3F2(g) + 3H2O(l) → O3(g) + 6HF(aq)
HF is highly permeable to mucous membranes, probably as a dual function of polarity and caustic action, which I would expect to assist in shifting equilibrium for further absorption through diffusion and further reaction.
Anyone know the kinetics involved? Chlorine behaves similarly, but is obviously distinguishable. It would be interesting to see how well F2 docked with olfactory GPCRs vs. HF if any plausible timeframe for action could be established.

Eddygp - 1-8-2014 at 06:17

I'm not particularly fond of inhaling halogens.

HgDinis25 - 1-8-2014 at 10:44

Like everyone has already stated, Chlorine smells like pool water. However, I can't stand it...

Iodine has a much better smell, like medicine or something like that, wich I kind of enjoy.

HCl, like woelen said, it's just extremly irritating. No smell at all.

NO2 has a distinct smell, comparing to Cl2. I find NO2 more tolerable, and in low concentrations, it smells like the exhaust smoke of a car, wich has NO2 in it.

SO2 and SO3 (not Halogens, just to compare) are very different from the gases described above. It smells bad, and it kind of sticks in your throat. It's very hard to explain it, but I find it very unconfortable.

AJKOER - 1-8-2014 at 13:53

Quote: Originally posted by HgDinis25  
Like everyone has already stated, Chlorine smells like pool water. However, I can't stand it...



I think there is a bit of mixing of the smell of Cl2O/HOCl and Cl2 here. Perhaps not coincidentally as:

Cl2 + H2O = HCl + HOCl

but I would argue they are different.

Interestingly, the poisonous properties of Cl2O and Cl2 also differ widely, in a fashion largely unknown by many.

So let's hope we can learn to differentiate the smells.

Texium - 1-8-2014 at 13:55

Quote: Originally posted by HgDinis25  
Like everyone has already stated, Chlorine smells like pool water. However, I can't stand it...

Iodine has a much better smell, like medicine or something like that, wich I kind of enjoy.

HCl, like woelen said, it's just extremly irritating. No smell at all.

NO2 has a distinct smell, comparing to Cl2. I find NO2 more tolerable, and in low concentrations, it smells like the exhaust smoke of a car, wich has NO2 in it.

SO2 and SO3 (not Halogens, just to compare) are very different from the gases described above. It smells bad, and it kind of sticks in your throat. It's very hard to explain it, but I find it very unconfortable.

I find my perceptions of all of them to match yours almost exactly. SO2 and SO3 are just evil. It's like sweet/metallic/irritating/rotten all mixed into one incomprehensible smell.

halogen - 2-8-2014 at 13:09

Depends whether I shower.

Mailinmypocket - 2-8-2014 at 13:35

Chlorine smells nice in low concentrations and is like nose rape in higher ones. I love the lingering smell of chlorine though. Clean and fresh.

Bromine has more of a stench, not terrible but less clean than chlorine. It also tends to raise my blood pressure a bit because almost every time I smell it I am either synthesizing a respectable quantity of it or using it in a reaction. It sticks to fabric and even walls it seems. The smell stays for hours, not bad... Not wonderful, just bromine. My favorite halogen though, so useful and relatively easy to manipulate.

Iodine smells very familiar and nice. I think it is because it is the first halogen I ever experimented with so it has something nostalgic and familiar about it, like an old friend. More metallic than the others perhaps. Never had an iodine nose rape like I have with Cl and Br thankfully.

Fluorine? No such luck. Thankfully.