The acid that really does eat through everything

acid burnThanks to the big screen, many of us think of acids as dangerous, burn-through-anything substances.  Think of those scenes in the Alien movies, where the alien’s blood drips through solid metal, destroying everything in its path.

Of course the vast majority of acids are much more boring.  Vinegar (which contains ethanoic acid) and citric acid (found in, guess what, citrus fruits) are common acids that we eat all the time, and they don’t burn holes in your mouth.  There’s an even stronger acid, hydrocholoric acid (HCl), in your stomach and not only does it not burn you from the inside out (usually), it actually helps you to digest your food and keeps you safe from nasty bacteria.

But there is an acid that’s really, properly scary.  And its name is hydrofluoric acid.

Hydrofluoric acid has the chemical formula HF, but unlike HCl you won’t find this one in a school laboratory, and if it turns up in your stomach you’re in very big trouble.  In true movie-acid style it’s capable of dissolving many materials, and is particularly well-known for its ability to dissolve glass (which is mainly silicon dioxide).  It will also dissolve most ceramics (which contain aluminosilicates: compounds made of chemically-bonded aluminium, silicon and oxygen).  And, like many other acids, it also reacts with metals, so storing it is a bit tricky.  Where do you put something that eats through its container? Well, these days it’s stored in special plastic bottles, but in the 17th century when it was first discovered chemists had to use glass bottles coated inside with wax, and hope the coating was a good one.

HF has been an important industrial chemical for centuries.  It’s used to etch patterns into, and clean, glass and ceramics, and also to dissolve rock samples, for example to extract chemicals or fossils from rocks.  It’s also used to clean stainless steel and, in more recent times, to prepare silicon wafers (used to make silicon chips) in the electronics industries.

The chemist Carl Wilhelm Scheele (him again – he just keeps turning up doesn’t he?) was the first person to produce HF in large quantities in 1771.  Scheele is particularly famous for his bad habit of sniffing and tasting any new substances he discovered.  Cumulative exposure to mercury, arsenic, lead, their compounds, hydrofluoric acid, and other substances took their toll on him and he died on 21 May 1786 at the age of just 43.  And that’s why your science teacher was endlessly telling you not to eat or drink in the laboratory.

So why is hydrogen fluoride so nasty?  For starters the gas is a severe poison that immediately and permanently damages the lungs and the corneas of the eyes – lovely. Hydrofluoric acid solution is a contact-poison that causes deep, initially painless burns which result in permanent tissue death. It also interferes with calcium metabolism, which means that exposure to it can and does cause cardiac arrest (heart attack) and death.  Contact with as little as 160 square centimeters (25 square inches) of skin can kill – that’s about the area of the palm of your hand.

And now for a gruesome and tragic tale: in 1995 a chemist working in Australia was sitting working at a fume cupboard and knocked over a small quantity (100-230 millilitres, about the equivalent of a drinking glass full of water) of hydrofluoric acid onto his lap, splashing both thighs.  He immediately washed his legs with water, jumped into a chlorinated swimming pool at the rear of the workplace, and stayed there for about 40 minutes before an ambulance arrived.  (Should you ever need to know, the proper treatment for HF exposure is calcium gluconate gel: calcium gluconate reacts very quickly with hydrofluoric acid to form non-toxic calcium fluoride, rendering it harmless.)  Sadly, his condition deteriorated in hospital and, despite having his right leg amputated 7 days after the accident, he died from multi-organ failure 15 days after hydrofluoric acid spill.  Remember, that was a spill the size of a glass of water.

Because hydrofluoric acid interferes with nerve function, burns from it often aren’t painful to begin with. Small accidental exposures can go unnoticed, which means that people don’t seek treatment straight away, making the whole thing worse.  Do a Google image search on ‘hydrogen fluoride burns’ and you’ll see some images that will really turn your stomach.

So which would you rather meet?  An alien with acid blood and a habit of laying eggs in your stomach or an invisible gas that destroys your tissues and leaves you, if not dead from multiple organ failure, then suffering with horribly disfiguring burns?  You might stand a better chance against the alien…

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23 thoughts on “The acid that really does eat through everything

    • Well, no HDPE isn’t particularly special, but I don’t reckon people store HF in recycled plastic milk bottles ;-) They make containers specifically for its storage. So they’re ‘special’ in that sense.

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  4. I have been poison’d with hydrochloric acid and need to know can hydrochloric acid be detected thur a hair test or finger nails or toe nails and what can I do to neutralize this hydrochloric acid because I know it is already in your stomach naturally but this is not a natural hydrochloric acid from inside your stomach. Any ideas because I have been to the ER hospital 6 times n had several medical test run and then I read online that hydrochloric acid can not be detected in low levels in your blood and when the doctors do not see anything in my blood they just don’t want to help me but I have been sick since the end of Feb. 2013 n its now Nov. 20, 2013 and my stool has just now turn’d back to a some what normal color but I am still sick everyday. Can anyone help ?

    • I’m sorry to hear about this. How did you come into contact with it? As this material safety data sheet describes, hydrochloric acid is corrosive and will cause serious damage to your respiratory tract if inhaled, and burns and skin irritation in contact with skin. Obviously it will damage your digestive tract if swallowed. If you swallowed it, the problem may be that it caused internal damage (i.e. burns) that have taken a long time to heal. There probably isn’t any more actual HCl in your system, but the internal damage could still be causing symptoms. However, I’m not an expert. You need to speak to someone who deals with poison control.

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  6. im just wondering if it were possible that we could probally use HF to maybe cure cancer. Maybe there is a way to somewhat “calm” down or make the substance weaker so that it is able to kill the cancer cells without harming the human body…
    (Im only 15 years old)

    • It’s an interesting idea. Chemotherapy drugs work along these lines: they’re pretty toxic chemicals on the whole, but in the doses taken to treat cancers they’re less harmful to the body as a whole, although they still cause pretty nasty side-effects. They generally work by preventing cancer cells from multiplying by interfering with their DNA. On the other hand, hydrofluoric acid is toxic because it reacts with blood calcium and removes Ca2+ ions from the blood. Without enough of these, your heart stops working. It doesn’t attack cells as such so it wouldn’t work as a cancer treatment. Also, because your blood calcium is so important, it’s extremely dangerous even in very tiny amounts.

  7. I hate reading but I like learning new things so sometimes cant stop reading but I still hate it, but that was a good read. I like that you’ve put a good amount of information in here so well done. Thank you

    • That’s great to hear, thanks! :-)
      As for hydrofluoric acid, you can buy it legitimately (for example, Fisher sell it), but you will need some kind of evidence that you’re using it for business or educational use. They won’t sell it to an individual. You might be able to get it by other means, but personally I wouldn’t mess about with a less than legit source. Who knows how it’s been stored, whether the packaging is up to scratch… it’s a genuine risk.

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