Talk:Hydrofluoric acid

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Contents 1 Could someone explain why it is so corrosive? 2 Fluorspar 3 Acid Constants 4 hydroflouric acid 5 Potato Chips 6 Hydrofluoric acid (data page) 7 Hydrofluoric acid (Reaction) 8 Nasty Stuff 9 HF Acid Attacking Bone matter 10 SiO2 is not "glass" 11 Safe % Concentration? 12 Dissolve plaster? 13 Records of undocumented incidents

[edit] Could someone explain why it is so corrosive?

I think we should add a section why HF, despite having such a low dissociation constant, is so corrosive. If the hydronium ions and fluoride ions are all latched together, how come it can react and dissolve all metals except iridium? (according to the strong acid page) Kr5t 05:46, 6 March 2007 (UTC)

[edit] Fluorspar

This page erroneously describes "feldspar" as calcium flouride. The correct word is "fluorspar." "Feldspar" refers specifically to silicates of aluminum.

[edit] Acid Constants

It'd be nice to have some data on acid constants in all of the pages on acids, really. But I'm afraid I don't have that data.

• This data is coming, at least to those acids covered by WikiProject Chemicals (which includes HF). From memory, the pK_a for HF is about 5. Physchim62 20:57, 29 May 2005 (UTC)

[edit] hydroflouric acid

Should hydroflouric acid be a misspelling rediret - it's quite common on Google (185 000) and I'm here because I wikified it on Erich Bagge and had to change the spelling that had been used there. Richard Taylor 13:30, 18 August 2005 (UTC)

Done. --Delirium 06:13, August 30, 2005 (UTC)

[edit] Potato Chips

There are also food applications for Hydrofluoric acid, including as a potato chip flavouring where it is useful as it can give the acidic flavor required in salt and vinegar potato chips without requiring a volume of liquid which would make the crisps soggy. Hydrofluoric acid is not used for this purpose in all of today's potato chips.

eating hydrofluoric acid?! is this for real?

No, vandalism. Sodium acetate is the compound most usually used for this effect, althouth there are others. Physchim62 (talk) 13:28, 6 April 2006 (UTC)

[edit] Hydrofluoric acid (data page)

Please see Talk:Hydrofluoric acid (data page)

Dear readers, I am here to say that what you had just read about hydrofluoric acid is a lie. My fellow friends edited the whole information on the subject on hydrofluoric acid.

I repeat don't believe the info that you just read on hydrofluoric acid.

[edit] Hydrofluoric acid (Reaction)

I am a university student from Malaysia, doing a research on how will hydrofluoric acid react with hydrogen peroxide? What will be the product? Is it dangerous? Thank you!

[edit] Nasty Stuff

People, it is best to keep clear of this acid. it is insane. Once saw a lab tech get some on his hand and he was screaming for it to be cut off because it hurt so much. they had to remove a chunk of his hand just to get the hydrofluric acid off. Its best left on the shelf guys.

Just be careful. Use it in small quantities in negative-pressure apparati.

I'd say if you don't have a REASON to be using it you shouldn't be. Like uranium. —The preceding unsigned comment was added by 74.104.1.193 (talk) 04:14, 11 December 2006 (UTC).

[edit] HF Acid Attacking Bone matter

The danger of HF attacking bone calcium and the is a bit over stated: "Exposure to hydrofluoric acid may not be initially painful, and symptoms may not occur until several hours later, when the acid begins to react with calcium in the bones." Wrong. Even with delayed effect the throbbing pain is caused by interference with nerve conduction. You do not have pain receptors in your bones. Death due to hypocalcaemia is more of a concern than necrosis of bone tissue. Exposure to the lungs may lead to death well before any you have to worry about your bones.

"Under most circumstances, hydrofluoric acid exposure results in severe or even lethal damage to the heart, liver, kidneys, and nerves." I have had HF burns, and I know two people hospitalized with serious HF burns from anhydrous HF exposure. They are alive and well and so are their heart, liver, kidneys, and nerves. Immediate medical attention is the key factor in treating hypocalcaemia and tissue necrosis.

What is not over stated: this is nasty stuff. Don't use it unless you know what to do and have access to the appropriate first aid treatments. You need to have a very good plan for working with HF.

• I agree, I will try to have a look at the safety section and keep it to the correct tone. The real risk, as you point out, is immobilisation of serum calcium not the attack of bone tissue: this is why the recommended fist aid is calcium gluconate gel, to flood the affected area with a relatively lipid soluble source of calcium ions. Physchim62 (talk) 08:38, 7 June 2006 (UTC)

[edit] SiO2 is not "glass"

the sentance "Hydrofluoric acid is notoriously known to dissolve glass (SiO2):" is grossly misleading at best. silica does not simply = glass!

Actually this statement is true, HF is used to etch glass. My A.P. chem teacher has a piece of glass that he etched his name into with HF. You must remeber that while glass is not pure SiO₂, it is the main constitute. Thus if you dissolve the SiO₂ you are left with compounds that seem to have little or no problem dissolving in HF, effectivly dissolving the "glass." Kyanite 01:37, 26 September 2006 (UTC) Yes, quartz glass is pure SiO2 and is used widely in semiconductor manufacturing. Other glasses such as float, optical, crystal etc. will contain other components, but almost all will have varying amounts of SiO2.

SiO₂ is used as an abbreviation for glass since it's the only chemical component that's especially important. Artificial glasses have additives ("flux") to reduce melting point and reduce viscosity (Na-B compounds are common), but the chemistry of the glass, especially its reactivity with HF, is dominated by SiO₂. Natural glasses are filled with all the things that are present in any rock. Using SiO₂ as an approximation for glass will accounts for the bulk of the system, especially when the topic of interest is "what HF does". The statement should be retained, since the primary importance of HF is to break the Si-O bond, which other acids can't do (only F is appropriately electronegative). This is why HF is used so ubiquitous in geochemistry. Blueschist 18:49, 9 February 2007 (UTC)

[edit] Safe % Concentration?

Does anyone know at what % concentrations HF becomes reasonably safe to handle? 1%? 0.5%?

It is classified as Harmful (Xn) in the European Union (under Directive 67/548/EEC as amended) down to 0.1% by mass. Physchim62 (talk) 14:54, 25 October 2006 (UTC)

[edit] Dissolve plaster?

Will this dissolve plaster that is skimmed over a brick wall? If so, where can this be purchased. Hydrochloric acid doesn't seem to do much of anything. --Kalmia 08:00, 25 October 2006 (UTC)

I'm sure it would dissolve plaster, but it will also attack the brick underneath. Further, it would be astonishingly dangerous to use in large volumes over large surfaces. The personal protective equipment that you use – even stuff resistant to hydrochloric acid – is apt to be a tender snack for HF. You might try asking at the Reference Desk for suggestions on other ways to remove the plaster, though. TenOfAllTrades(talk) 14:23, 25 October 2006 (UTC)

HF is not actually very good for dissolving plaster (mostly calcium sulfate), as calcium fluoride is pretty insoluble in water. It is also, of course, ludicrously dangerous! Hydrochloric acid is what is usually used: the commercial stuff in France is 22% and works pretty well (HCl has its own safety problems, but less than HF). Physchim62 (talk) 14:48, 25 October 2006 (UTC)

Using HF to dissolve plaster is like using an eraser made of anthrax to erase a mark on the wall. That is to say, a bad idea. Kr5t 05:42, 6 March 2007 (UTC)

I still can't believe that "washing the car with HF" citation in the article. The reference reads more like some kind of complex April Fool's joke, though one printed in January. Maybe the concentrations are at borderline homeopathic levels, but the notion of washing a car with the help of HF strikes me as unable to rise above the merely stupid... mdf 18:13, 23 March 2007 (UTC)

[edit] Records of undocumented incidents

"records indicating the occurrence of such incidents are not well documented"

I'm intrigued. How does anybody know? -- Ianiceboy 08:12, 14 February 2007 (UTC)