How dangerous is 1:60 HF (hydrofluoric acid)?

[Waterman]

@Andy

@FoieGrasIsEvil

I don’t understand why anyone would call HF a “weak” acid because it is extremely corrosive (I am not a chemist, though).

Think of it like this; 10M NaOH solution is an amazingly weak acid, but boy is it corrosive. Acidity ≠ corrosiveness.

Not to belabor the point but in this thread you state that you are a chemist:

How effective is baking soda at reducing odours?

I have no idea where you claim to have obtained your Chemistry credentials but your contribution to this thread is an insult to the profession. As someone else pointed out, the comparison of 10 M NaOH as a weak acid is just simply absurd. As a strong base it could be regarded as a weak acid but why would this ever be mentioned.

Apparently the objective of fighting ignorance is not a priority of Andy

[septimus]

@Blake

Ironically, the weaker the HF solution the more dangerous it usually is in practice. A strong solution will cause a burn within an hour, and the victim will then usually seek medical help. Weak solutions may not cause bruns for 10 hours or more. The victim goes home, goes to sleep and dies of a heart attack while asleep.

I found this post interesting. I think if I were working with such stuff, I’d always shower afterwards, no?

On another matter, though IANAC:

@Waterman

@Andy

Think of it like this; 10M NaOH solution is an amazingly weak acid, but boy is it corrosive. Acidity ≠ corrosiveness.

I have no idea where you claim to have obtained your Chemistry credentials but your contribution to this thread is an insult to the profession.

Even I figured out what Andy meant. Amazingly enough it was the word “amazingly” that gave it away. Andy’s post might have given other readers more credit that they deserve, but resembles the terse, slightly tongue-in-cheek, comments I might make.

The insults against Andy were way out of proportion.

[astro]

[quote=“Reply, post:17, topic:553682”]

@kidchameleon

Really? Liquids can penetrate skin like that?

There are liquids like DMSO that can go into/through skin like it was’t there. I don’t mean destroy the skin I mean go into it.

Use of DMSO in medicine dates from around 1963, when a University of Oregon Medical School team, headed by Stanley Jacob, discovered it could penetrate the skin and other membranes without damaging them and could carry other compounds into a biological system. In medicine, DMSO is predominantly used as a topical analgesic, a vehicle for topical application of pharmaceuticals, as an anti-inflammatory, and an antioxidant.[citation needed]. Because DMSO increases the rate of absorption of some compounds through organic tissues including skin, it can be used as a drug delivery system. It is frequently compounded with antifungal medications, enabling them to penetrate not just skin but also toe and fingernails

You can take DMSO, which is a liquid, and put a small amount on the sole of your foot. It penetrates through the skin, and all other material in your body with extreme speed and you will “taste” the DMSO in your mouth almost instantly. The taste is normally not considered a “pleasant” taste, but it is certainly not dangerous to do this. The taste will be very characteristic of DMSO, somewhat like kerosene

[WarmNPrickly]

@Waterman

@Andy

Think of it like this; 10M NaOH solution is an amazingly weak acid, but boy is it corrosive. Acidity ≠ corrosiveness.

Not to belabor the point but in this thread you state that you are a chemist:

How effective is baking soda at reducing odours? - Factual Questions - Straight Dope Message Board

I have no idea where you claim to have obtained your Chemistry credentials but your contribution to this thread is an insult to the profession. As someone else pointed out, the comparison of 10 M NaOH as a weak acid is just simply absurd. As a strong base it could be regarded as a weak acid but why would this ever be mentioned.

Apparently the objective of fighting ignorance is not a priority of Andy

Andy statement is perfectly clear and certainly not an insult to the profesion.

There are better examples though.

The corrosiveness of HF generally comes from the fluoride. Sodium fluoride would also be corrosive. OTOH, weak acids can be corrosive as well. The phosphoric acid in Coke is certainly strong enough to take the paint off you car.

[JoeH2O]

As an aside, I wonder what the equilibrium constant of NaOH <-> NaO- + H+ actually is, since I assume it does actually dissociate this way in an extremely unfavourable manner, and clearly the loss of the hydroxide ion is the predominant mechanism.

By the chemistry definition, it does fit the description for a weak acid; it’s just one of those situations that are counterintuitive, like the fact that balsa wood is actually a hardwood.

(Not that I think that “weak acid” is a suitable description for sodium hydroxide beyond analogies about corrosiveness).

[notsoheavyd3]

[quote=“astro, post:23, topic:553682”]

@Reply

There are liquids like DMSO that can go into/through skin like it was’t there. I don’t mean destroy the skin I mean go into it.

Or even worse Dimethyl Mercury which can go through a rubber glove and then through your skin and then kill you.

Don’t forget to read the Karen WetterHahn link too. BTW, don’t confuse Dimethyl Mercury with plain old elemental mercury. (I know the anti-vaccine loons try to say they’re the same and they’re not.)

[Gary_Robson]

@Waterman

I have no idea where you claim to have obtained your Chemistry credentials but your contribution to this thread is an insult to the profession. As someone else pointed out, the comparison of 10 M NaOH as a weak acid is just simply absurd. As a strong base it could be regarded as a weak acid but why would this ever be mentioned.

Apparently the objective of fighting ignorance is not a priority of Andy

[moderating]
Keep the personal insults out of GQ, Waterman.
[/moderating]

[kidchameleon]

@astro

There are liquids like DMSO that can go into/through skin like it was’t there. I don’t mean destroy the skin I mean go into it.

You know, I seem to run into a whole bunch of this stuff in my strange life as a chemist. In my early years we were doing some drug testing with some acidified DMSO and being a newb, I had to suck it up in a syringe and push it through a .22 micron filter, which was a lot of work on my poor thumbs. Well, about the third or fourth time through, the filter I had on must have been defective or got clogged by something. So I just pushed harder. And harder. Until the luer connection broke, spraying me in the face with the acidified DMSO. Luckily I had prescription safety glasses with plastic side shields. I doused my face in the eye wash, though at that point it was probably to late to be of much effect. Nothing ever happened to me but I still have those glasses with the side shields, the side shields are discolored where the DMSO hit them.

Another fun bit about DMSO is we had a 4L out on the loading dock overnight and it froze (September-ish in DC). As it melted, it did so in a honey-comb fashion.

[Waterman]

I had not considered the possibility of sarcasm, etc in the post by Andy and therefore withdraw my previous comment with apologies. While no excuse, I suspect that I must have not been in the best mood last night:rolleyes:

[robert_columbia]

@Andy

@FoieGrasIsEvil

I don’t understand why anyone would call HF a “weak” acid because it is extremely corrosive (I am not a chemist, though).

Think of it like this; 10M NaOH solution is an amazingly weak acid, but boy is it corrosive. Acidity ≠ corrosiveness.

Umm… NaOH is not an acid at all, it is a base. If you mix it in the right proportions with HCl(aq), you get a solution of NaCl in H20 (that is, NaCl(aq)), which is better known as salt water.

And the difference between a weak acid and a strong acid is not how corrosive or dangerous it is, but as previously mentioned, the amount to which it ionizes in water. Strong acids like HCl and H2SO4 (sulfuric acid) ionize almost completely in water, while weak acids like HF, citric acid, ascorbic acid (vitamin a), acetic acid (vinegar), ionize only slightly.

[WarmNPrickly]

Acids and bases are just two ends of the same scale. OH- can certainly lose a proton to become O2-. I have no idea what that pKa is, or if it has even been calculated or measured. TI think it was pretty clear from the post, that Andy was using the term exactly in that context.
I don’t know why that simple post has caused so much controversy.