Talk:Hexafluorosilicic acid

Proposed move to hexafluorosilicic acid

1) Although on some planets "Dihydrogen hexafluorosilicate" might be common, this name is rarely heard by chemists on earth.

2) Using the highly unreliable Google test: Dihydrogen hexafluorosilicate returned 850 hits, and hexafluorosilicic acid gave 16000.

I therefore propose to move this article (while it is still young and stubby) to "hexafluorosilicic acid", where it will grow deeper roots. Complaints, comments, concerns, etc?--Smokefoot 01:08, 27 January 2007 (UTC)

3) The same comment also applies to the recently modified Infobox:

| SystematicName = Dihydrogen hexafluorosilanediuide
| OtherNames = Dihydrogen perfluorosilanediuide

These two very unusual names are automatically generated by a very rarely used computer program, and only appear on the websites of some small dealers selling chemicals and using this program to build their catalogs.

A Google search with "Dihydrogen hexafluorosilanediuide" only delivers 7 results, most pointing to: http://www.molport.com

http://www.molport.com/buy-chemicals/molecular-formula/F6H2Si

However, Sigma Aldrich, a much more known chemical supplier only use the name hexafluorosilicic acid:

http://www.sigmaaldrich.com/catalog/Lookup.do?N5=CAS+No.&N3=mode+matchpartialmax&N4=16961-83-4&D7=0&D10=&N25=0&N1=S_ID&ST=RS&F=PR

The mistake in the blind use of this computer program to generate so-called but false IUPAC names is to attempt to apply the systematic of carbon to inorganic substances. However, R- only refers to a hydrogen atom or to an organic group, not to an inorganic group such as the fluoride anion. Shinkolobwe (talk) 18:28, 28 November 2010 (UTC)

Safety info

Smokefoot removed properly cited safety information without comment. What is the purpose of this action? This deletion will be reverted. Petergkeyes (talk) 02:35, 26 May 2008 (UTC)

Because I felt that your contribution included a serious omission. Here's your quote: "Contains trace elements including lead and arsenic." First, obviously hexafluorosilicate contains traces of other elements - everything does. And here is the quote from the Brits "Trace elements such as lead and arsenic are present in minute quantities in fluoride compounds. But, because of the very high dilution factor, fluoridation makes no measurable contribution to the concentration of these substances in the water supplies." I also thought that your inclusion of extensive safety warnings, which exceeed the level of wording we provide to most chemicals, was (i) giving advice (see Wikipedia:What Wikipedia is not) and (ii) out of proportion. But do what you gotta do. The editors are accustomed to a high level of, shall we say, "enthusiasm" from those interested in fluoridation. --Smokefoot (talk) 02:47, 26 May 2008 (UTC)

Arsenic Cancer Death Estimate=

ahem, i'll just leave this here; "The typical arsenic contamination seen in Ontario, Canada from hydrofluorosilicic acid certificates of analysis is also reflected in the NSF “averages”. According to data from the NRC 2004 Report on Arsenic, 6 out of 100,000 people would get cancer as a result of the arsenic added to our drinking water from this source. For a city the size of Toronto with about 5 million individuals, 300 deaths/year from cancer may be attributed to fluorosilicate usage". —Preceding unsigned comment added by 220.101.92.34 (talk) 09:29, 6 May 2011 (UTC)

Ahem (makes you sound both knowledgeable and subtle simultaneously, which is way-cool!), a reference to publication on that point would certain be welcome on these talk pages. Be careful that anti-fluoride groups are widespread on the WWW, and their revelations are usually pretty unreliable. Their reports appear to be well intentioned, but are authored by uneducated (totally chemically illiterate) conspiracy theorists. Thanks for the note.--Smokefoot (talk) 12:50, 6 May 2011 (UTC)

I have cut down the safety information to a minimum. We don't give this excessive level of detail in any other chemical articles. If you want to discuss how much safety info should be in chem articles, go and post a message at WP:CHEMS, but don't re-add the text unless you get consensus here.

I removed the bit of arsenic and lead, too, since there was no explanation of why this information is important. The sentence did seem to imply that the presence of these toxic metals poses a risk to people who drink water that has been treated with hexafluorosilic acid - this is not the case (concentrations too low to matter), as the reference provided points out.

Ben (talk) 22:27, 26 May 2008 (UTC)

Took a quick look at Wikiproject: Chemicals. Didn't see anything there discouraging posting safety precautions or trace elements, but please point it out if I missed something.

Ben, I don't think HFSA "treats" water. If you were on, say, dialysis, I don't imagine you would want any of your water to be "treated" with this substance.

I was responding to this plea: "This inorganic compound-related article is a stub. You can help Wikipedia by expanding it." The "Safety" section refered to another substance, but was barren of any safety precautions. I'm not clear on why posting safety precautions are being discouraged on this page. Petergkeyes (talk) 04:16, 27 May 2008 (UTC)

I said don't re-add your bit till you get the green light! I'm going to ask others to get involved.

Just because a tag says "expand", doesn't mean you can add bad content at will. Read Wikipedia:Tendentious editing.

If this safety info is going to be in the article, it should be added to the several R- and S-phrases that are already found in the chembox. This is really the only appropriate place for information of this kind. If it is going in the body of the article, re-write it in proper prose, providing appropriate references for not just the facts but their importance.

Ben (talk) 05:55, 27 May 2008 (UTC)

This statement has been shown not to be true: "Hexafluorosilic acid, like other compounds used to fluoridate drinking water, contains trace elements such as lead and arsenic. However, the dilution factor is so high that fluoridation causes no measurable increase in the concentrations of these elements in drinking water." The quote is undated, and judging by its citations, may be as old as 1993. It does not take into account the data on silicofluorides and lead that have been emerging in the past decade. I propose adding this text:

In 2001, Dr Roger Masters reported that, "taking economic, social and racial factors into account, where silicofluorides are used, children absorb more lead from the environment." Petergkeyes (talk) 00:08, 28 May 2008 (UTC)

Might want to rephrase that to make it less emotive (children absorb lead!) but, yes, stick that in. What it does not say is that the trace amounts of Pb and As found in hexafluorosilic acid are the sources of this extra absorbed lead.

Ben (talk) 06:37, 28 May 2008 (UTC)

Um, no. Hexafluorosilic acid does not contain anything other than hydrogen, silicon and fluorine. The solutions of HSiF₆ used for fluoridation may do, but that is a matter for discussion on the fluoridation pages, not here. It's not a property of the acid, it's a property of the way the solutions are made. Why not move the comment about lead and arsenic to the fluoridation pages? Chris (talk) 08:02, 28 May 2008 (UTC)

Yeah, that's an even better proposal. But don't write "little children will die" or similar. I'm sure any toxic effect affects adults, too.

Ben (talk) 13:22, 28 May 2008 (UTC)

How's this:

H2SiF6, as used in water fluoridation, contains traces of contaminants such as lead and arsenic, but in quantities so minute that they are often undetectable. Petergkeyes (talk) 22:03, 28 May 2008 (UTC)

In fact, there's no need to mention that H₂SiF₆ solutions used in fluoridation contain traces of Pb and As because it has no consequence. Don't write it in any article - it is a (possibly) true but irrelevant fact.

Ben (talk) 22:27, 28 May 2008 (UTC)

Probably every chemical compound on the market has traces of arsenic and lead. Analytical reagent-grade sulfuric acid from Mallinckrodt Baker has up to 1 ppm Pb and 0.01 ppm As.[1] U.S. Pharmacopeia-grade sodium chloride has up to 1 ppm As and 2 ppm Pb.[2] And so on. The real question is whether such traces are relevant or not. But common sense suggests that if you take H2SiF6 with a few ppm of Pb and As, and dilute it so that you have a few ppm of fluoride, as is done for water fluoridation, you will be adding at most a few parts per trillion of Pb and As to the drinking water. That's negligible by any standard other than homeopathy. ;-) --Itub (talk) 08:24, 29 May 2008 (UTC)

Have removed this information; true, but irrelevant ;) Chris (talk) 10:10, 29 May 2008 (UTC)

Just to jump in - I think people are more likely get exposed to lead in drinking water through lead pipes than any trace impurity present in the manufacture of this compound. I agree with the above - elements Pb and As are not part of this compound, the compound only contains the elements Si, F and H. Talking about other elements is a red-herring IMO -- Quantockgoblin (talk) 12:48, 29 May 2008 (UTC)

References

Controversy between UK and EU

There is a substantial controversy taking place in UK and Ireland, where HFSA is used for water fluoridation, and in EU where use of HFSA failed a formal vote by the safety commission. Several anti-fluoridation groups have taken up the flag and are agitating for cessation of fluoridation in UK. Should this be referenced in this article at all? Opinions? NReitzel (talk) 15:27, 6 June 2008 (UTC)

If it should go anywhere, it should be at water fluoridation controversy. --Rifleman 82 (talk) 15:45, 6 June 2008 (UTC)

Yes, this should certainly go in with a link to the controversy article. The main place where HFSA is used is in fluoridation -- 90% of the US is fluoridated with silicofluorides and fluosilic acid, where it is a very controversial issue. This certainly should be noted in the article. One major source is:

• Coplan, M. J.; Patch, S. C.; Masters, R. D.; Bachman, M. S. (2007), "Confirmation of and explanations for elevated blood lead and other disorders in children exposed to water disinfection and fluoridation chemicals", Neurotoxicology, 28 (5): 1032–1042, doi:10.1016/j.neuro.2007.02.012{{citation}}: CS1 maint: multiple names: authors list (link)

I'll wait and hear what others have to say. Unfortunately I'm going by the abstract, and if someone could check the article and maybe let me glance over it, I would appreciate it. If you glance at the Table of Contents, you will see references to the literature on this issue. Urbansky[3] disagrees with Masters&Coplan, who may be relying on Westendorf's dissertation[4] -- Update: Masters&Coplan may be citing this article. The NAS comments on the issue and doesn't really take a conclusive side either way.[5] I'm not saying that this deserves a large paragraph, but I think the part of the fluoridation controversy directly centered upon HFSA should be documented here. II | (t - c) 08:58, 23 July 2008 (UTC)

The antifluoridation advocates have proven so active that at least three articles have been created within Wikipedia that address this controversy - fluoride poisoning, water fluoridation controversy, dental fluorosis. These articles are largely written by antifluoridation-advocates. So the perspective from Wikipedia chemistry group is to cede these controversy articles to the advocates, but strive to keep the pure chemical articles soberly focused on the chemical, per se. The present article is not intended as a self-help guide, nor an almanac, nor a manual for good health. It's just an article about a chemical.--Smokefoot (talk) 13:06, 23 July 2008 (UTC)

Can the fluoridation brigade create a section in water fluoridation controversy specifically about HFSA? Then we can have one direct link from this article to that section, where all discussion of controversy can go, e.g.:

For the use of hexafluorosilicic acid in fluoridation, see Water fluoridation controversy#Hexafluorosilicic acid.

That way, chemical articles can be about chemistry and controversy articles can be about controversy.

Ben (talk) 13:18, 23 July 2008 (UTC)

That seems fine by me. I'm amused by Smokefoot's comments -- all of those concepts are completely distinct and referenced in completely distinct ways in scientific literature. Fluoride poisoning usually refers to the acute effects of occupational exposure to fluoride. Dental fluorosis is a high-profile dentistry concept which is recognized as a major concern by the EPA, CDC and ADA quite distinct from any relationship to the opposition movement. II | (t - c) 22:56, 23 July 2008 (UTC)

Uses

I'm removing the reference to "Virtually all chemicals used in artificial fluoridation schemes are waste by-products (fluorosilicates) derived from phosphoric acid production pollution scrubbers." From uses, it's not relevant to the use.
I would move it to the Production section, however there is another contradictory claim there and the source it is attributed to is "Self Published" at best, as far as i can see it shouldn't be included at all. —Preceding unsigned comment added by Bobby 783 (talk • contribs) 16:39, 24 March 2009 (UTC)

Thanks for your edits, I was the one (I think) that inserted the tangential "Virtually all chemicals ... scrubbers" I was over-reacting to the self-published claim that recovery of a chemical from a mining operation somehow presents a special problem. I just removed that EU petition citation because it lacks any sense of authority, IMHO. This article once was regularly edited by folks alarmed by water fluoridation and seeking to insert claims, data, as well as innuendos to advance their cause (that fluoridation is a bad idea or possibly a conspiracy).--Smokefoot (talk) 21:44, 24 March 2009 (UTC)

And it was edited by me. The edit was to add a subheading "Water Fluoridation" under "Uses" heading and to add a link to the fluoridation controversy page. I did not add any innuendos. What was inappropriate about my edit? You gave the reason "illiterate". Can you explain what I did wrong?

The reader does not need to know inorganic chemistry to know that this chemical is added to municipal water. For example, California Statewide Fluoridation Table produces the following chart for public viewing, listing H2SiF6 (among other things) http://www.cdph.ca.gov/certlic/drinkingwater/Documents/Fluoridation/PWS%20Statewide%20Fluoridation%20Table%202011.pdf

The public is expected to read that document but "H2SiF6" isn't explained. Those who search the web, might find this Wikipedia page and from that, see the link to "Water Fluoridation" and then the link to the controversy page. All highly appropriate (and one does not need a degree in [neuro]biology or inorganic chem to reference or review studies about effects of water fluoridation).

Also, in the subheading for Water fluoridation, why not summarize in a sentence or two the controversy?

All of this is reasonable and has already been discussed in this page. Deletion of that for zealotry or snobbery is biased and unreasonable. This page needs this info. If you can explain what is "illiterate", maybe I can help avoid that. Awaiting your response. Xkit (talk) 02:30, 27 November 2011 (UTC)

Misleading new category: Category:Silanuides

The new Category:Silanuides is inadequate and misleading and should be deleted. Moreover, it only contains 3 pages:

• Ammonium fluorosilicate
• Hexafluorosilicic acid
• Sodium fluorosilicate

Please, discuss this concern here: Wikipedia_talk:WikiProject_Chemicals#Reorganization_of_Category:Silicon_compounds_cattree

Best regards, Shinkolobwe (talk) 18:41, 28 November 2010 (UTC)

Oh these categories are just crazy stuff implemented by PlasmaPhysics. No one else seems to like PlasmaPhysics work, but it takes time to undo the damage and nutty categories. Go ahead and delete the cat's as you have time.--Smokefoot (talk) 19:01, 28 November 2010 (UTC)

Thank you for confirming this point of view. I do not like to undo the work of others. So, I spent some time to argument the issue for Plasmic Physics and to delete this category to protect our readers. Best regards, Shinkolobwe (talk) 22:14, 28 November 2010 (UTC)

Source links

I noticed that source #11 is a dead link, and source #12 is supposed to support the LD50 figure by linking to an MSDS, but it links to the MSDS of caffeine instead of hexafluorosilicic acid. (user hardifesses, 25 Nov 15)

External links modified

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Grandjean and water fluoridation

An anonymous editor recently attempted to add Grandjean and Landrigan's 2014 The Lancet commentary on neurotoxicants ([6]) in support of the assertion that municipal water fluoridation [7] could cause a "an accumulated [fluoride] overdose and create serious medical issues". This statement is entirely unsupported by the linked commentary, which says nothing at all about municipal water fluoridation.

For reference, Grandjean and Landrigan base their own assessment of fluoride's potential neurotoxicity on Grandjean's 2012 paper (Choi et al.) which involved a meta-analysis of several mostly-small, mostly Chinese studies looking at areas with very high levels of naturally-occurring fluoride in their drinking water. In these studies, the control (that is, the so-called low-fluoride) groups often were drinking water with naturally-occurring fluoride concentrations similar to those seen in artificial water fluoridation. The high-fluoride groups (in which potential neurotoxic effects were observed) were exposed to significantly higher fluoride concentrations.

These sources have already been discussed to death at the talk pages of water fluoridation and water fluoridation controversy; the latter paper is cited appropriately and in context at fluoride toxicity. TenOfAllTrades(talk) 06:49, 5 January 2017 (UTC)

Question

"Hexafluorosilicic acid has a distinctive sour taste and pungent smell."

Isn't it toxic? I've heard that very experienced chemists actually found out the taste of KCN but I'm pretty sure that HF is much more toxic than KCN so... --My Contributions Contact me -- GoyangCityBoy 04:48, 29 December 2019 (UTC) — Preceding unsigned comment added by GoyangCityBoy (talk • contribs)

Where on earth did you read that hexafluorosilicic acid be especially toxic? In solution is consists of the octahedral SiF₆^2- ion, and such polyatomic anions tend to be relatively innocuous (think sulfate, perchlorate, hexafluorophate, etc). The other point: HF is far less toxic than KCN. You could eat grams of NaF and would get a tummy ache. In some parts of the world, NaF is or at least was put into milk or bread for cavity protection. Cyanide is a different critter because it binds so tightly to Fe in a variety of proteins that are involves with O₂ processes. If you can find a source (textbooks, review journal, technical reports) on these toxicities, editors here are always interested. Thanks for the note. --Smokefoot (talk) 23:45, 29 December 2019 (UTC)

"Fluorosilicic acid hydrolyses, releasing corrosive HF" and HF is toxic. --My Contributions Contact me -- GoyangCityBoy 03:07, 6 February 2020 (UTC) — Preceding unsigned comment added by GoyangCityBoy (talk • contribs)

Error

"Hexafluorosilicic acid is generally assumed to consist of oxonium ions charge balanced by hexafluorosilicate dianions as well as water." No, water cannot charge-balance anything. Water is neutral.Eudialytos (talk) 20:15, 23 April 2020 (UTC)

The idea is that H₃O⁺ or something like that H₅O₂⁺, etc. is the countercation. --Smokefoot (talk) 22:51, 23 April 2020 (UTC)

@Smokefoot: I've tagged that for now. I wonder where this idea comes from. Why would water oxygen become positively charged (from O^-2 to O²⁺, O⁴⁺, O⁶⁺) upon contact with HF? To become positively charged it has to lose 2 electrons and additionally 2 to 4 electrons over it (take look at the oxygen electron orbitals). Please provide a source. AXONOV (talk) ⚑ 17:47, 25 May 2022 (UTC)

@Alexander Davronov: Wwater oxygen is routinely protonated in all acidic aqueous solutions, in inverse proportion to pH. Source: any high school or introductory chem text. Your puzzlement is an opportunity to learn that the focus is not on oxygen losing electrons to become positively charged but to attract protons. H₃O⁺ is a close analogue of H₃N (ammonia). And ammonia also protonates to give ammonium, NH₄⁺. No electrons are added or removed, the positive charge comes from H+, an otherwise very rare ion. I hope that this helps. The orbital analysis is not needed. --Smokefoot (talk) 15:15, 1 June 2022 (UTC)

@Smokefoot: So there is no source? Hydrogen has only 1 electron and 1 proton. It can't add up more positive charges to the molecule as it has no valence electrons to bind with. Hydrogen cations are less electronegative than oxygen anion and can't rip electrons away like fluoride does in some molecules, see the latter's oxidation states. When I talked about orbitals I meant electronegativity and oxidation states. AXONOV (talk) ⚑ 16:39, 1 June 2022 (UTC)

Hi Alexander: you need to talk to someone else because your comments reveal a misunderstanding of basic chemistry. Actually your comments are just stupid. I am sure you are well intentioned and smart in many ways, but you need to talk to someone who can explain hydrogen bonding, atoms vs ions, and stuff like that. No harm done, --Smokefoot (talk) 02:02, 2 June 2022 (UTC)

Please see WP:NPA. AXONOV (talk) ⚑ 21:44, 2 June 2022 (UTC)

Water decomposition

I think we have to clarify that hexafluorosilicic acid decomposes in water only upon heating. I think the source says just that [8]. Implicitly though. AXONOV (talk) ⚑ 18:22, 25 May 2022 (UTC)

@Alexander Davronov: No, I think that source is just missing a paragraph break. It should probably read "When heated to decomposition...hydrogen gas.¶ In water....", so that the heating and the hydration are completely separate experiments.

To be fair, its stability equilibria are subtle, and the current article omits that complexity. Ullmann gives an equilibrium constant for hydration (10⁻²⁷) that indicates hyrolysis really isn't spontaneous, except when working with hard drinking water. I'll try to incorporate some more material from the Ullmann citation etc. to clear up the ambiguity. Bernanke's Crossbow (talk) 19:48, 27 February 2024 (UTC)

Thanks. More clarity is welcome. It seems decomposition in water is more complex than I thought. AXONOV (talk) ⚑ 07:31, 9 March 2024 (UTC)