4/24/2007

"F is for Freaky." part one

I'll attribute the title quote to a prof here who happens to be a fluorine chemist. (It happened to stick in my mind, and now maybe it will stick in yours.) I suppose he's right, though. Fluorine is an electron-hungry little beast, and it does some interesting things when stuck onto other atoms.
Not all of these interesting things are desirable, mind you. I don't know many chemists who aren't familiar with the hazards of hydrofluoric acid. This is completely off the Milkshake scale of relative toxicity, way beyond gangsta badass and in its own little world of ninja badass.[1]
Its sneaky means of badass ninja-style chemist assassination has been widely documented, so I'll not go into further detail. It is interesting to note, however, that many car washes and detailling shops are using HF, as well as the likewise-not-so-friendly ammonium bifluoride, as a wheel cleaner. There's a nice little article about it here. While HF has its place as a glass etch and as a silicon wafer cleaner in the semiconductor industry, I'm not so sure it's a good idea to risk lives in order to get those rims extra shiny.[2]

A more serious second part of this post is in the works. Finals week, however, calls for fluff posts. April depression calls for ninjas in the living room.


[1] Ψ*Ψ is not actually a ninja. She is clearly unable to adopt a properly serious ninja stance. She shares with the ninja a certain degree of secrecy about her location, though.
[2] No matter how much you like shiny things.

12 comments:

Chemgeek said...

WTF!!!! HF in the car wash???? I can honestly say, I never knew this.

From now on, I'm rolling up the window. No matter how thirsty I am.

Mitch said...

Awww. what a cute picture. :)

Mitch

Liberal Arts Chemist said...

F chemists get all the respect and none of the glory. Anhydrous HF is the worlds best solvent for making crystals (if your material survives the solution process). Going to a F Chem Conference is weirdly like the scene from Jaws where they compare scars though the elite members of the club have all lost body parts. HF rocks in so many ways but you NEVER turn your back on it. Ever. We had an HF accident a long time ago where a graduate student ended up with pretty severe damage to her leg ... she lived with it for a few years but it ended badly and my supervisor insisted on a buddy system whenever we used HF after that.

Propter Doc said...

Weak HF is in many window cleaning products in the UK.

Dr R spilt HF down himself last summer. That was a fun trip to the hospital.;-( Knowing exactly what to do (strip ASAP, water, antedote gel) helped, as did training all his lab workers in advance how to respond to such an event. In the end there wasn't a mark on him.

I don't think he's used HF since...

milkshake said...

I heard of one not so brilliant peptide chemist in Prague who got some diluted HF on his hands (after taking apart flask with the anh HF - cleaved resin). He did not notice at first because it did not hurt on the fingers - but he went to bathroom and contaminated himself down under. No lasting damage but first few days were reportedly very painful. I would spare you the details but let say a jar of cold water put een the bed matrasses at night was used so that he could get some sleep, because of the pain of these burns. The problem with diluted HF is that by the time you notice that it hurts a lot of damage was done to you already.

Uncle Al said...

Ammonium hydrogen bifluoride, (NH4)+ (HF2)-, is a choice self-buffering aqueous fluoride etch. Its huge surface tension breaks with a drop of Fluorad surfactant (Dawn dishwashing liquid in a pinch). Uncle Al removed silicates from a few kilos of -20/+40 mesh solvent-washed (no bitumen; bitchin' six-foot soxhlet), HCl-washed (no limestone), oil shale (calcareous marlstone with 30 wt-% kerogen on a good day).

After vacuum drying the fluffy beige organics spontaneously smoldered in air. Uncle Al did such a good job... that he got a pink slip write-down. The (impossible) project goal was removing kerogen from oil shale. Uncle Al insubordinately removed the rock from oil shale leaving pristine kerogen. Management was livid with rage.

Uncle Al was granted no time to describe a trace of heavy black powder residual after the fluoride etch. Iron pyrites would have burned in a graphite pocket under a glassblowing torch. This stuff eventually melted to give a tiny yellow bead after cooling.

David Eaton said...

I had a student in a pchem lab ( a ChemE student) who co-oped in a plant where they used HF for something or another- in any case, they would get leaks in overhead pipes, which he could tell from the drips on the floor that ate into the concrete.

Speaking of really dangerous shit, ChemE's for whom I TA'd always astounded me with their lack of curiosity and their inability to detect when calculations didn't make sense. This same guy did a determination of the vapor pressure vs temp of butanol for the lab. In his report, he plotted a negative kelvin temp against a log of pressure that started at 32, which made me sorry I had not been in the lab when this particular experiment had been performed. It would have been uproarious at least, and damned impressive if he actually achieved negative absolute temperatures and big-bang magnitude pressure.

When he and those like him graduate (and despite my best efforts to flunk his ass, he did graduate) they go on to make phat cash running chemical plants full of HF and pesticides and methyl bromide and apparently, they won't be alarmed when the pressure gauge reads >10^30.

Chem E's make the bucks, but, frankly, their chemistry kung fu is weak. Nowhere near ninja.

Ψ*Ψ said...

If this Chem E went to school where I'm guessing he did...well, all I can say is that things haven't changed much.

milkshake said...

but the *realy* badass ninja actually belly-dance first - and then they slay the audience

Ψ*Ψ said...

No dice, Milkshake.

Matt Jenks said...

But that makes no sense. You can't see the ninjas when they're coming. Watching one belly dance would be like staring at a blank wall.

sushi said...
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