[lemonoman]

So yeah, I got word today that tomorrow I'll be using Hydrofluoric acid in some experiments.  If you ask me, it's not the best idea, but hey, it's good experience.  As long as you're really careful it should be okay, but lab coat, gloves, goggles, are ESSENTIAL as a bare minimum.  Anybody here used that stuff before?  Do tell.

[Donaldson Tan]

Isn't HF the weakest acid among the hydrogen halides?

[movies]

Yes, in terms of pKa, but the others don't leech the calcium out of your bones until you die from it.

Might I recommend the MSDS?

[Mitch]

Whenever I used it, I also wore dishwashing gloves above regular gloves; just for that added protection.

[Donaldson Tan]

although it's a weak acid, HF is still very hazardous. hmm.. i think i miss out all that chemistry stuff u all learned at college. Maybe I should switch course after all.

[hmx9123]

HF is a very dangerous acid.  If you have to use a lot of it for your lab, or multiple students are using it, a bucket of magnesium sulfate solution should be around to immerse your hands or arms in should you get burned by the acid.  If you get it on your skin, you may not know it for 30 seconds or more (some say up to a minute or two), but then it feels like a someone is cutting your joints apart with a dull, rusty spoon very slowly.  It sucks.  You also need to be worried about it dissolving the glass or whatever else you're working with and forming toxic gasses.  It can make polyfluorinated silanes, all of which are toxic.  Thus it needs to be done in a fume hood.  Of course, many of these things are less of a concern if the acid is very dilute, but they are still concerns nonetheless.

[lemonoman]

Well, for the general information of the public, I think ain't gonnabe no sissy acid.  I was told that if I'm not careful, the cappillary tube (for gas chromstography) will disintegrate into the acid.  Not cool.

Dishwashing gloves sound like a marvelous idea.  I mean. my supervisor said they've never had a problem, but they've never had ME do an experiment either...haha

Thanks everyone for the input.  I like this place.

[Dude]

At the lab scale, HF isn't a real problem as long as you keep it away from glass and off your hands (like all acids).  The reputation of HF as being a super-toxic chemical comes mostly from the potential for "clouding" if it is released in large amounts.  HF is still used as an alkylation reagent at some large refineries.  If released into the atmosphere, most gases dissipate and diffuse into the surrounding air quickly.  Because of the tendency of HF (due to its strong dipole) to aggregate to itself and dissipate very slowly into the surrounding air, it can be damaging via inhalation.  HF is kind of like the piranha fish (hope I spelled that correctly).  One and there is no problem.  Many and you better leave.

[arnyk]

Acid halides are pretty nasty in general, maybe not the actual acidity itself but all the extra calcium leeching abilities.  

The only reason it's a "weaker" acid is because of the strong H-F bond making it difficult to remove the proton.

[jdurg]

To sum it up, as an acid HF is incredibly weak.

As a compound, HF is incredibly toxic.

[xiankai]

http://en.wikipedia.org/wiki/Hydrogen_halide

it says HF is a stronger acid... is it wrong or anything? just want to clear up matters

[movies]

Yeah, that Wikipedia page was pretty blatantly wrong.  I fixed it.

[Donaldson Tan]

This topic should be renamed to "Most Hazardous Acid and my Third Day of Lab"

 

[lemonoman]

Agreed.  But it's in the past.  Hazard = Power nowdays anyways

Well it's been 24 hours, so the HF experience is over with.  No burns, no feelings of the joints being ground away by rusty spoons.

Mental note, do'nt be so agitated next time.  Stay careful, but don't have a fit. lol

[hmx9123]

HF is actually a super acid when anhydrous.  In polar aprotic solvents, it's extremely strong.  It's just that in aqueous solutions where it's most often encountered, it is weak.  I think there's a thread on it in the very early forums.  I'm sure AWK will come along and correct this statement somehow soon.