master
Joined: May 2003
Posts: 8,430
St Charles MO
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Quote:
Quote:
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. 
HF is one of those fascinating albeit terrifying chemicals. You spill it on you, treat it immediately by flushing, think OK, it's not burning. Yet, up to 8 hrs later, you may start burning, blistering, getting your lungs full of water, muscle spasms, even death when untreated. It does not stop reacting. And you brush your teeth with Fluoride!
No matter how responsible he may seem, never give your gun to a monkey!
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