Saturday, March 21, 2009

HF is in what?

Today in Pennsylvania, a truck carrying hydrofluoric acid (HF) overturned. had a story about it. As so often happens, the main stream media continues to display a certain degree of scientific illiteracy.

In the story the author wrote:
It also is an ingredient in high-octane gasoline, refrigerants, aluminum and light bulbs.
HF is indeed a nasty little molecule that demands a great deal of respect, but I can assure you, it is NOT an ingredient in gasoline, refrigerants, aluminum and light bulbs. HF is used in the manufacturing of these things, but it is not an ingredient. A subtle difference, but an important one. Even a quick Wikipedia search could have helped.

If you don't understand science, don't write AP stories related to science. That's why I don't write AP stories about poetry, cricket or knitting. I know what these things are, but I don't know enough to be accurate.

NOTE: I was going include a picture showing some HF accidents, but some of them were too gruesome. I didn't want to gross out any unsuspecting reader. Do your own search.


Liberal Arts Chemist said...

Testify. I worked in a lab where we used anhydrous HF as a solvent in glass vessels. You are right about the photos. HF has the nasty property of painlessly dissolving into the skin down to the subcutaneous levels and then ripping things apart with horrible pain. We had special safety showers, neutralizing chemical baths and first aid treatment stations IN our lab. We still had a horrific accident that came about because a female graduate student would not admit she had spilled the HF until it was too late. She lost a lot of the muscle in the upper part of her leg and never walked normally again.

My brother who works in an oil refinery as the safety officer told me how once a month they bring in a new rail car load of HF. He made it sound like the docking of the shuttle to the space station.

I would note that the article I read indicated that it was gaseous (or anhydrous) HF. That would make clean-up a lot easier as long as there was good wind dilution / dispersion.

Chemgeek said...

I believe it was anhydrous HF, but there was another puzzling line in the CNN story: "Most of the acid was in the form of pressurized gas."

Either it was gas or it was in solution. Technically, I suppose HF gas that had escaped would no longer be considered 'pressurized.'

Liberal Arts Chemist said...

Yeah, anhydrous HF is like anhydrous HCl in that it is a gas at room temperature and normal pressure. Around 5 atmospheres (the limit for well made glassware) the gas (or more accurately a vapour) condenses as a liquid. The tanker could have been filled with liquid anhydrous HF that quickly vapourized when the tank ruptured.

The concentrated solution of HF is evil on wheels and if the tanker had have been filled with that we would have had an incident worthy of a majour new story.

katiedid said...

Wow, I didn't realize HF was trucked around the country... which I guess shows my ignorance because I didn't realize it was used in the manufacture of everyday stuff. I just thought it was something used in small amounts in the lab.

milkshake said...

Liberal arts chemist; you got the data wrong, anhydrous hydrogen fluoride is a liquid that boils around room temperature. My handbook says 19.5C boiling point. I worked in peptide lab where they condensed HF straight from a tank with cooling the vessel on ice bath, and they used teflon apparatus of course. The 5 atm pressure you mention must be related to the fact that HF (anh) comes in steel cylinders. HF is not supposed to react with steel when anhydrous but in reality it does though very slowly. Decades-old HF tanks found in storage rooms are dangerous as they are likely to be over-pressurized with hydrogen.

A tanker full of anhydrous HF must have been lots of fun. We had a trailer loaded with giant drums of fuming nitric acid that overturned on highway in San Francisco few years back. It shut down the traffic for the whole day, and they prevented most of the content from the leaky drums from spilling out. The highway needed re-surfacing afterwards.

brian12566 said...

I wish the media would take your advice relating to chemistry and police work. If I hear "routine traffice stop" one more time...there is no such thing as a routine traffic stop.

the iNDefatigable mjenks said...

Yes...nothing could go wrong with adding some HF to the glass lightbulbs. Nothing at all.

Chemgeek said...

Katiedid: These occasions are great for spurring one to learn things. A lot of this I didn't know before I looked into it. I learn each day.

Milkshake: Thanks for the clarification.

Brian: We should all be very thankful there are officers out there who gladly do the "routine stops." The events in Oakland should remind us that every stop can be deadly. My neighbor works in law enforcement and a few years ago (long story short) he stopped a meth-head who then tried to run my neighbor over. My neighbor had no choice but to shoot and kill the driver. It made the danger associated with law enforcement a much more personal thing.

Mjenks: maybe they meant teflon lightbulbs. That would be something.

Lisa-tastrophies said...

Ok, Liberal Arts Chemist scared the sh*t out of me with the comment about "painlessly dissolving into the skin down to the subcutaneous levels and then ripping things apart with horrible pain".

And ditto on the media doing some fact checking. It I hear one more thing about the "bird" flu being this "New" flu I am going to throw something at someone. We've seen it 4 times before not to mention the damn thing have to mutate with the "normal" human flu before it "cobrates" into the "new" bird flu. Damn people do some research the CDC spells it out right on their home page.....
Oh sorry, was I off on my soap box again. I get a little passionate for epidimology some times.

Chemgeek said...

Lisa: I agree. I've exposed my subcutaneous tissue to sunlight too many times. One should not do such things

Liberal Arts Chemist said...

Oh hey, I don't know if this thread is dead or not yet but sorry for the misinformation. Milkshake is absolutely right about the physical properties. Our vessels were supposed to be good to 5 atm because of incedental SiF4generation from the reaction of the HF with residual water on the surface of the glass not the HF itself. Oddly aqueous HF etches glass but anhydrous HF does not (but it will scavenge any surface H2O).

Eric said...

They concentrate it to save on shipping? Wouldn't just about any acid be dangerous in superfluous or anhydrated forms (I'm not a chemist or media person)?

Good point about the media, I've been watching them spin economic reporting for years.