I need to qualify this. I know that hydrogen flouride dissasociates completely and has a really high proton-donating capability and all that; however, HF is stored in PLASTIC!?!? containers. That sounds like a pretty wimp-ass acid to me.
I guess what I really want to know is which acid will eat through the most stuff, the fastest.
This all stems from a long-ago junior high class in which I was told that sulphuric acid could eat through ANYTHING, and I was always interested in what the heck they stored the damn stuff in. (Glass bottles, apparently).
It would be my guess that sulfuric acid is definitely up there, but HF is also considered a strong acid. One thing to note though, is that HF is TOXIC. My orgo prof used to joke that if you had a choice to be splashed with acid, choose the “stronger” acid (lower pH – however, this is not the only way to measure acid strength), such as HCl. There’s also a trend on the periodic table, as you go down the column, you’ll get stronger acids. It would be something like HI > HBr > HCl > HF withina column.
Well, you’re thinking about this the wrong way; of course acids like HF and H2SO4 won’t dissolve plastic. That’s not any kind of measure of their strength since dissolution is a matter of ‘like dissolves like’. Plastic and (inorganic) acids have very little in common chemically, since plastics are generally long strings or sheets of chlorinated polymers. HF is used to etch glass, which is an uncommon ability among acids but that’s not a measure of its strength so much as its unique chemistry.
In general, there’s really no easy answer to this. You could talk about pH or pKa and the concentration of acid (pure HCl and H2SO4, as in 0% water, actually have little acidic power but that’s fairly theoretical as just about anything that you’d be trying to dissolve would have water available for it to mix with) and it’s important to know what substance you’re talking about. It also depends on your definition of acid (no, really).
HF, spilled on less than 2.5% of your skin, will kill you. It will rip the metals out of your cells and burn your bones. All in all, pretty cool. Anothe strong one is carbonic acid. You can get really strong stuff when you go into organic acids, but I forget most of it.
Damn, I forgot about Aqua Regia, or Queen’s Water. Alchemists toyed with it a lot. On a side note, another thing that will dissolve gold is a certain mixture of ammonia and other chemicals, which makes gold fulminate, or blow up.
As a person who has been burned by many acids, I can say that nitric is a bad mamma-jamma. It also leaves that nice yellow stain on anything organic.
Also, we must consider molarity. Glacial acetic acid will do a lot more than .4 molar HCl.
It’s not aqua regia itself that dissolves gold; it’s the chlorine liberated by the mixture of nitric and hydrochloric acids. That will dissolve gold.
It’s necessary to note the distinction between hydrogen compounds and acids, although all acids contain hydrogen. To make it plainer, all strong acids are liquid; and chemical reactions of any kind are faster when the substance is dissolved. That is why the poisonous metal barium, which is used in intestinal treatments (I know; I once had a barium enema–it was pure hell!) can’t harm you; its compounds will not dissolve in water, or in intestinal fluids, and only dissolved substances can be absorbed across the intestinal walls. Hydrocholric acid, in fact, is an important component of gastric juices; Isaac Asimov noted in The Human Body (pp.217-218), “Its existence among the delicate tissues of the body was first discovered in 1824 and it came as quite a shock to biologists.” Hydrochloric acid in fact has the lowest pH of any acid–0.
I asked my high-school chemistrey teacher what would happen if you dropped a penny into nitric acid. He showed me–with a square of copper he cut from a small sheet. The HNO3 foamed light green, and when it cleared the copper was gone. :eek:
I was waiting for someone to mention conc Nitric Acid–However, I don’t know about just yellow stains–I’ve seen holes on organic things…fingers included…
I remember from chemistry class (and I got A’s as a matter of course–no pun intended) trying exactly that experiment, with the Big 3: Sulphuric, Hydrochloric and Nitric.
Nitric kicked ass. I mean, just burned through anything: school tie, eraser, pen nib, human hair. Like the stuff in Alien.
The A’s abruptly stopped coming when I tried to see what nitric would do when combined with hydrochloric.
Seriously, though (although the above really happened) triflic acid and fluorosulfonic acid are possibly the strongest acids on earth.
I work with HF; not entirely true at least not with 5% and 49% HF. If HF is spilled on you it feels like water. Utill about 30 - 45 minutes later when the acid works it way down to your bone and starts to eat it away then you’ll wish you were dead.
As for the strongest acid? I can’t remember the name of the stuff but all I know is; if it goes past its experation date we have to call the bomb squad in to get rid of the stuff. Its so dangerous that they have to use a robot to go in and get it. then they clear the parking lot or take it to a field then explode it. And oh yeah, all they have to do to explode it is drop the freaking bottle.
It’s been a while since I did chemistry, but isn’t pH defined as a logarithmic measure of the concentration of hydogen ions, ie. protons? Then pure protons would technically be acidic.
Of course, there’d be more immediate problems, like a large explosion. But it’d be a) low pH and b) dangerous, which seems to be what’s desired.
Chemists define acid strength by how much of an acid dissociates when it’s dissolved in water. By that measure, as Blake said, hydrofluoric acid is a weak acid because it doesn’t dissociate very much. It attacks glass, though, because it reacts with the glass to form a gas, which I think is silicon tetrafluoride. That’s why you have to keep it in plastic, while much stronger stuff like nitric acid can be kept in glass.
The hydrogen ions at the core of the sun (H[sup]+[/sup]) are packed together at a density of ~160 g/cm[sup]3[/sup]. That’s 160,000 g/L or, dividing by the atomic mass, 160,000 Molar hydrogen ions. Since pH = -log([H[sup]+[/sup]]), the center of the sun has a pH of -5.2. That’s plenty strong acid ! Plus it’s hot enough to burn holes in most anything. Rumor has it that the physicists are still 30 years away from building a bottle that could hold the stuff.
It’s been a while since I took chem, but I remember learning that the strongest acid (or common acid at least) is perchloric acid (HClO4). Any chemists care to comment on this? What would make this stronger than HCl, H2SO4 or HNO3?
The perchlorate ion is a stronger oxidizer than chloride, sulphate, or nitrate. That means that it has a higher affinity for electrons. Thus the bond between the hydrogen and the ClO[sub]4[/sub] ion has more ionic character than that between H and the other anions.
