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Topic: Mercury vapors  (Read 13238 times)

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Offline constant thinker

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Mercury vapors
« on: May 04, 2005, 08:45:39 PM »
What is the vapor that mercury emits at room temperature. Is it just mercury in a gaseous state or is it something else. At what concentration is mercury lethal it if you know it off the top of your head.
The periodic table I viewed only said that mercury was a liquid at room temperatue which I already knew. It also said that it emitted toxic vapors at room temperature.
« Last Edit: May 04, 2005, 08:48:00 PM by constant thinker »
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Offline jdurg

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Re:Mercury vapors
« Reply #1 on: May 04, 2005, 08:54:22 PM »
Mercury vapor, as far as I am aware, is just elemental mercury in a gaseous state.  Mercury has a pretty high vapor pressure, so if a puddle is left out in the open a good deal of it will evaporate into the air.  This is why it's not good to have an open container of mercury, or a container with which the Hg can escape.

For the toxic amount, I don't recall off the top of my head.  From what I can remember, Hg is not particularly toxic in the acute sense, but over the long term it is quite toxic indeed.  That is why you should NEVER work with mercury on a carpeted floor.  A solid, large tiled floor is the best surface as the Hg really cannot soak in and slowly leach out over time.
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Offline constant thinker

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Re:Mercury vapors
« Reply #2 on: May 04, 2005, 09:17:23 PM »
Ok thank you. I knew mercury was very dangerous mainly because of its vapors. Fast response also.
"The nine most terrifying words in the English language are, 'I'm from the government and I'm here to help.' " -Ronald Reagan

"I'm for anything that gets you through the night, be it prayer, tranquilizers, or a bottle of Jack Daniels." -Frank Sinatra

savoy7

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Re:Mercury vapors
« Reply #3 on: May 05, 2005, 06:42:15 PM »
to add to jdurg

how toxic is Hg?

this depends on: 1) type of Hg - metallic, inorganic or organic
2) mode of delivery - inhaled, skin contact or ingested
3) concentration

Usually it affects the kidney & in metallic and inorganic - the brain

doing a quick look on the internet I found this site which provided some good information
http://www.mass.gov/dep/files/mercury/appd.htm


Offline hmx9123

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Re:Mercury vapors
« Reply #4 on: May 06, 2005, 06:20:49 AM »
You know, I always roll my eyes when people say mercury has a high vapor pressure.  Sure, it has a high vapor pressure for a metal.  It does NOT have a high vapor pressure compared to things we normally think of as having a high vapor pressure, like acetone, benzene, etc.  I've heard toluene referred to as having a 'low vapor pressure'.  It's really how you look at it.  If you're used to dealing with inorganic salts, then cool, mercury has a reasonable vapor pressure (1.8^-3 torr, IIRC).  But for Pete's sake, benzene has a vapor pressure of something like 75 torr.  That's 5 orders of magnitude more.  Acetone has a vapor pressure of 400 Torr!  I have never heard of mercury appreciably evaporating no matter how much the surface area.  I knew a glassblower who worked 20 years in a facility which had a pool of mercury on the floor near his desk that was about 2.5 m2 the entire time he was there.  He and all his co-workers were tested for mercury.  None of them even had a trace.  Bear in mind that they not only breathed this crap, but they worked with mercury itself.

Read the Merck Index entry on mercury.  You can swallow the amoun in a thermometer with no problems.  People always make metallic mercury out to be a bigger deal than it is.  In the way of toxic stuff in the lab, it's not that bad.  Seriously.  You should be careful, but it's not the end of the world.  People are way less careful with things that are much more dangerous because they are ignorant of the dangers there and because they're ignorant of the relative benign nature of metallic mercury and only believe the media hype.  It is true, there are some mercury compounds that are extremely toxic, like mercury salts and dimethylmercury.  The latter is the cause of the major media hype, and it IS a major problem, but the media always just says 'mercury'.  Dimethyl mercury comes from fish, and they get it from our power plants burning the stuff (where it comes out as a metal, bypasses us because it isn't so toxic, then heads down to the bottom of the ocean where bacteria transform it into dimethylmercury, and then fish eat crustaceans filled with it).  There's a great article in C&EN about it from a few months back.

Anyway, I'll get off my soapbox now.
« Last Edit: May 06, 2005, 06:24:22 AM by hmx9123 »

Offline jdurg

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Re:Mercury vapors
« Reply #5 on: May 06, 2005, 09:26:33 AM »
You can have a ton of mercury hanging around as long as you have good ventillation.  Also, if there is a big open space then the mercury vapor concentration won't be that high.  (I don't imagine a glassblower's room to be a small confined area).  If that same puddle of mercury existed in a smaller office type area, then it would be a big problem.  As I said earlier, mercury is a cumulative poison.  One exposure isn't going to do squat.  If you have that level of exposure over a long period of time, then it will surely begin to affect you.  A professor of mine my freshman year of college is a pretty good example of this.  He had a bit of a tremor, and some of the other classic signs of mercury poisoning.  He used to work with mercury all the time and was in rooms where gallons of the stuff were just lying open.  To him, it was nothing and he never thought anything of it.  When you have a puddle of mercury that leaches into some concrete or gets absorbed into some wood flooring or carpet, over time it will leach out of it and into the air around you.  Being a cumulative poison, you may not notice the effects now but it will affect you over time.  (For your story about the glassblower there hmx, I do sense a good deal of exaggeration because even though mercury wasn't considered that toxic for a long period of time, nobody would allow a large puddle of that size to just sit around for 20 years).
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Offline constant thinker

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Re:Mercury vapors
« Reply #6 on: May 06, 2005, 07:30:47 PM »
Intresting points. I'm now realizing that toxcity mainly matters on the mercury compound, and that there are a significant number of them. My question has been answered and more. Thanks.
"The nine most terrifying words in the English language are, 'I'm from the government and I'm here to help.' " -Ronald Reagan

"I'm for anything that gets you through the night, be it prayer, tranquilizers, or a bottle of Jack Daniels." -Frank Sinatra

Offline hmx9123

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Re:Mercury vapors
« Reply #7 on: May 06, 2005, 08:30:36 PM »
That was one thing that I didn't mention--mercury is a cumulative poison, which is a problem.  That means if you get 1g in you today, you'll have 1g in you 40 years from now.  (Unless you ate more).  Yes, you're right, when you're constantly exposed to it over years and years, it may become a problem.  The glassblower story isn't exaggerated.  The guy who told it to me is one of the most understated fellows I've met, and he didn't think it was a big deal.  There are a few things about it that make it more believeable: 1. The glassblower is pretty old, so this wasn't recent--it was one of his first jobs.  2. All glass shops have TONS of ventilation, and are absolutely HUGE places--the ceilings are incredibly high to keep from burning down. 3. It was a small company that couldn't afford to pay for cleanup, so they ignored the problem and it just got worse over the years.  They did eventually clean it up.

So, yes, if you're constantly exposed, it may be a problem, but the exaggeration I see all over about people not wanting to touch mercury metal makes me want to laugh.  You're not going to get mercury poisoning or even get mercury in you by touching metallic mercury for a short while.  I wouldn't advise keeping it in your home, but you really need to watch out for the compounds of mercury, especially the organomercury compounds.

Offline mike

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Re:Mercury vapors
« Reply #8 on: September 28, 2005, 11:14:16 PM »
I wouldn't advise keeping it in your home, but you really need to watch out for the compounds of mercury, especially the organomercury compounds.

you're not wrong!

you guys have probably seen this article before:

http://www.udel.edu/OHS/dartmouth/drtmtharticle.html
There is no science without fancy, and no art without facts.

Hbond

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Re:Mercury vapors
« Reply #9 on: November 01, 2005, 09:22:03 PM »
The old fashion dental fillings were a silver/mercury analgom. These would be placed in a person's mouth and last 20 years. Mercury is quite stable but will oxidize over time and lower its vapor pressure.

AgG

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Re:Mercury vapors
« Reply #10 on: November 04, 2005, 03:14:38 AM »
My understanding is that Hg2+ is the toxic form of mercury, being methylated in the body by methylcobalamin to give HgMe+ which is readily absorbed into fatty tissues.  Hg2+ is a soft metal ion and will bind to soft ligands, namely -S type groups that are predominant in proteins.  Binding of the Hg2+ is irreversible in biological systems (chelators aside) and works to disrupt and unfold proteins. Hg(0) does not have this same ability and I do not know where the poisoning comes from in the case of liquid mercury and I would very much like to know if anyone has any ideas.

Offline xiankai

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Re:Mercury vapors
« Reply #11 on: November 04, 2005, 06:48:00 AM »
i think that because mercury is a metal, it has metallic bonding, thus having free ions and electrons. furthermore in the liquid state, those ions/electrons would be more mobile.
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Offline jdurg

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Re:Mercury vapors
« Reply #12 on: November 04, 2005, 10:12:25 AM »
My understanding is that Hg2+ is the toxic form of mercury, being methylated in the body by methylcobalamin to give HgMe+ which is readily absorbed into fatty tissues.  Hg2+ is a soft metal ion and will bind to soft ligands, namely -S type groups that are predominant in proteins.  Binding of the Hg2+ is irreversible in biological systems (chelators aside) and works to disrupt and unfold proteins. Hg(0) does not have this same ability and I do not know where the poisoning comes from in the case of liquid mercury and I would very much like to know if anyone has any ideas.

The human body does a damned good job of converting metallic mercury into an organic mercury compound or a soluble mercury salt.  That's where the poisoning comes from in regards to the elemental stuff.
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