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Now HF will kill you. It is both a strong acid and very very toxic, and will absorb into the body on contact through your skin. H2SO4 can also be considerably more dangerous than HCl, depending on concentration.

I'm all for doing the right thing, but today's hysteria over everything being toxic is simply mis-information. In our 5 second sound bit society, we don't even bother with the details of science.



HF (hydrofluoric acid) is actually a weak acid (pKa = 6.8X10^-4), but it can etch (ie. digest) glass. [The larger the pKa value, the more it will ionize in water which leads to its acid strength via the formation of the hydronium ion, H3O+(aq).] Hydrofluoric acid is used as such in glass/mirror shops, although they tend to favor the active paste salts in usage. H2SO4 (sulfuric acid) is stronger than HF because it can ionize in solution to approximately 100% ions. So, each molecule of H2SO4 generates 2 molecules of hydronium ions in water. HNO3 (nitric acid) can also ionize 100%, as well as the dreaded HClO4 (perchloric acid). I do not handle perchloric acid unless I absolutely have to, as it can eat flesh to the bone (even after flushing with copious amounts of water) unless neutralized with the right base. It also forms explosive metal perchlorate salts upon contact with nearby metal surfaces. Only those who are properly trained in safely handling such materials should be using said materials in the first place....

Yes, chemicals tend to get a bad reputation in the media. One thing I teach in my chemistry classes is that there are no "bad" chemicals. It all depends on how they are being used and why. The key to the message is to not fear chemicals (as the media would like), but to respect what they can do by learning about them....

If you do not know how to handle a certain chemical, it is better to leave it to the professionals who do....



Nuke 1, I'm certainly not a chemistry teacher but I have worked with these things daily for 38 years. To say that HF acid is weak may be misleading to those reading this. It is the most dangerous to humans of any listed here so far (nitric is close), such that even our drivers have to carry calcium gluconate to transport factory sealed drums of it. Exposure without treatment can lead to death within 24 hours or so. So perhaps "weak" as in ability to eat things but "lethal" as in human contact might be a better description? Again, not trying to split hairs here, just trying as always to keep members from getting hurt or worse.



Sorry for the late reply, I have been tied up all day with a outcomes meeting for chemistry coursework. You are absolutely correct that HF is dangerous to handle and I thank you for pointing that out on here. I do not want someone thinking that they can substitute HF for HCl in an acid bath without serious consequences....

What I was implying in my above post was that HF is a weakly ionizing acid in water compared to other acids, not that it is not dangerous to humans upon contact. I should have worded it better in the above post. (Chemists measure acid strength by how much the acid can form ions in solution: pKa disassociation values listed in tables from measurements. HCl is stronger in acid strength than HF in this manner. That does not mean that HF is less harmful than HCl though, even in diluted forms.) HF can remove the calcium from bones over time upon contact with flesh if not treated quickly enough. In comparison with perchloric acid, HF and HClO4 are both deadly if used wrong, but HClO4 can also explode when it comes into contact with many other commonly found chemicals. It can form explosive vapors if the bottle is not sealed properly in storage if not sequestered in a separate acid cabinet made only for HClO4 (can not be made of wood). On the old diamond scale found on many MSDS, HClO4 had a reactivity rating of a 3 (severe), while HF only had a 1 (minor) because of this issue. Both had a rating of 3 or higher on health, depending upon the purity of the solution tested, meaning that they need to be respected for what they can do. Either one of those acids is better left to trained professionals....