Take the 2-minute tour ×  I've read that Hydrofluoric acid (HF)
is extremely dangerous to touch, but what exactly makes it so
toxic? It's weak acid ($K_a = 7.2 \times 10^{–4}$) and
dissociates approximately 1/1000 as much as Hydrochloric acid
does in water, so why is it so much more dangerous? Wouldn't a
stronger acid cause more damage? What exactly happens when human
skin comes into contact with Hydrofluoric acid that causes it to
be so lethal?  share|improve this question add comment  1 Answer
The confusion arises from the term weak, which has only to be
interpreted in chemical terms.  Weak acid, as you say, just
means that the acid does not readily dissociates, not that its
effect are weak! Just to say one, HF corrodes glass, something
that not even smoking HCl does.  Wikipedia has a nice summary of
HF toxicity (see also the references in the article itself):
Hydrofluoric acid is a highly corrosive liquid and is a contact
poison. It should be handled with extreme care, beyond that
accorded to other miner