Talk:Phosphoric acid/Archives/2020

Random notes without a heading
Also known as Mofoic acid —Preceding unsigned comment added by 146.6.80.58 (talk) 23:20, 14 October 2007 (UTC)

Other interesting information could be: Phosphoric acid producers, such as Thermphos International B.V. (www.thermphos.com)

And about Phosphate esters, these are not made from H3PO4 but from P2O5 (Phosphorus pentoxide), PPA (Polyphosphoric acid: highly concentrated phosphoric acid) or POCl3 (Phosphorus oxychloride). I wouldn't mention them here.

Else: there are several ways to produce phosphoric acid, from Wet acid (green acid) that is obtained through the sulphur process described here, but also through a Thermal process, that produces very pure phosphoric acid through the reaction of Water with elemental phosphorus (Yellow phosphorus).

- MahRain. 14 november 2005.

IMHO this article is a real mess:

1. It barely touches on the actual subject of phosphoric acids (of which there are an infinite number in a very rich structural system, but 3 important ones, ortho-, meta- and pyro-);
 * Offline, I've started writing a separate article about these other phosphoric acid forms. It's currently on the temporary page User:H Padleckas/Temp (Phosphoric acids and Phosphates)  H Padleckas 17:58, 14 May 2005 (UTC)  H Padleckas 09:00, 19 Jun 2005 (UTC)
 * Finally, I've finished the main illustration for this article and I've moved the temp page to regular article status; see Phosphoric acids and Phosphates. This article remains about orthophosphoric acid.  I've added an note to this effect in the introductory section of this article.  H Padleckas 08:45, 24 October 2005 (UTC)
 * In addition to the article being about orthophosphoric acid, I' ve expanded the article to briefly discuss phosphoric acid as a chemical/reagent and mention the orthophosphoric can be heated to dehydrate it into metaphosphoric acid. Pyrophosphoric acid is currently not mentioned in this article, but there is a link to Phosphoric acids and Phosphates where pyrophosphoric acid is mentioned.  H Padleckas 15:28, 24 June 2006 (UTC)

2. Yet it lurches off to discuss irrelevancies like eutrophication from phosphate detergents (this isn't the phosphate article!) while missing all but one or two of the many uses for this important material;

3. It introduces a lot of dubious material which will need fact checking (local anaesthetic?! colour me very skeptical);

4. It is totally disorganised (section "Chemical properties" contains no chemical properties, section "Preparation of phosphoric acid" contains 11 words on one method of preparation while the whole rest of the section is totally unrelated, etc). I suggest hydrochloric acid might make a good template;
 * I' ve expanded am expanding the article to add more on chemistry of orthophosphoric acid. H Padleckas 15:28, 24 June 2006 (UTC)  H Padleckas 20:21, 25 June 2006 (UTC)

5. The section "Processed food use" is at best POV (agro-industrial chemical ?!? They don't use fertiliser grade acid in colas!) and probably just wrong (citric acid ... obtainable from lemons and limes--sorry, nope, it's an agro-industrial chemical made by the Aspergillus niger mould fermenting scrap molasses and waste starch hydrolysates, and it works best if you add some ... phosphoric acid!);

6. The section "Effects on bone calcium" seems very suspicious. In particular, the claim When an excess of phosphorus (through phosphoric acid, for example) is introduced, the body's chemical balance mechanisms will attempt to maintain the proper calcium-phosphorus ionic ratio by extracting calcium from the bones is exactly the opposite of what would be expected from Le Chatelier's principle and not what is expected for normal homeostasis, but hey, biology is a funny thing, if someone comes up with a reputable cite I'll believe it. If not, I'll remove it. I'm foreshadowing all this here because I have a really long backlog and it might be a while before I get to it. Anyone else, please jump in first if you can. -- Securiger 11:21, 28 Mar 2005 (UTC)


 * I agree with at least items 1 and 4 above. I have previously noticed this article was "wanting" in the chemistry areas and I was hoping to improve it as I got a chance.  I'm the person who originally wrote the chemistry section of Hydrochloric acid and the mono-, di-, and tri-, etc. protic acid subsection in the article Acid.  I was hoping someday to expand on the chemistry aspects of phosphoric acid in this article, but things take time.  H Padleckas 19:09, 28 Mar 2005 (UTC)
 * Physchim62 had added a Table of Properties for Orthophosphoric acid, which is good. The chemical structure pic is enlarged from the original to fit the table template and has become somewhat fuzzy.  Is there any way to reduce this pic size to the original 118x118 pixel size?  I would still like to write a Chemistry section at the beginnining of the article, but Physchim62 may beat me to it.  I will have to coordinate with him.  H Padleckas 08:45, 24 October 2005 (UTC)
 * Finally, I' ve expanded am expanding the article to add more on chemistry of orthophosphoric acid. H Padleckas 15:28, 24 June 2006 (UTC)  H Padleckas 20:21, 25 June 2006 (UTC)

I just deleted the detergent stuff. Phosphoric acid is not phosphate and it is not used in detergent.


 * I completely agree with the above- this desperately needs a lot of chemistry added, though currently I'm buried in other work. Walkerma 09:15, 14 May 2005 (UTC)


 * Looks like you're making good progress on your temp page, Henry. A couple of suggestions- (a) Don't forget the biochemical importance of the conjugate bases- there is a whole page on pyrophosphate, and if you search on "triphosphate" you find a lot of pages containing the word. (b) Could I suggest that phosphate esters DO belong on the page, but phosphite esters are at a different oxidation state and should be considered separately IMHO. I will be writing a page on phosphite esters later in the summer, with a view to writing up the Horner-Wadsworth-Emmons reaction that uses them. Keep up the good work, Walkerma 02:19, 20 Jun 2005 (UTC)
 * As mentioned above, I moved this temp page contents to the regular article page Phosphoric acids and Phosphates. I'm sorry about the delay, but it took me a while to make the main illustration for it.  See Talk:Phosphoric acids and Phosphates for responses to suggestions a) and b) above.  H Padleckas 08:45, 24 October 2005 (UTC)

June 24 edits made by 152,163.100.66
The edits made by 152,163.100.66 on June 24, 2006 were actually made by me, H Padleckas. It appeared to me as if I was logged on, which is how I usually make my edits, but somehow only the IP address is listed in the contributions history. 152.163.100.130 14:46, 24 June 2006 (UTC) H Padleckas 15:10, 24 June 2006 (UTC)

Rust stripping method
A very old rust stripping method uses zinc and sulphuric acid. The steel part is immersed in water in contact with a piece of scrap zinc casting. A little battery acid is added. Add acid until after a few minutes bubbles can be seen coming off the steel. Leave the work in the solution until rust removal is seen to be complete. Remove and wash. Protect from re-rusting immediately, as the steel will be in a very rustable condition. Also remove and wash the zinc for later use or the remaining acid will simply corrode it away to nothing. Pays to mechanically remove flaking rust first or you will simply be using up chemical and zinc for no good reason. This method works very well for pieces of all sizes but it does pay not to load the solution with lots of bits as it seems to slow down rust removal quite substantially, possibly because it is not easy to ensure good electrical contact between lots of bits and the zinc. Use of a steel sieve is really helpful for stripping small parts as this acts as a good contact. Happy stripping. Evan. —Preceding unsigned comment added by 125.237.171.82 (talk) 07:57, 8 June 2008 (UTC)
 * Informative comment, but does it have anything to do with the Phosphoric acid article? H Padleckas (talk) 05:26, 2 June 2009 (UTC)

Anesthetic?
The article currently claims that phosphoric acid is used as an anesthetic. Can anyone confirm or deny this?


 * Sounds suspicious to me, but then as said above, bio can be a funny thing. Walkerma 09:15, 14 May 2005 (UTC)

Darrien 08:42, 2005 May 14 (UTC)

I am an assistant professor of anesthesia at a Canadian teaching hospital. I have never heard of phosphoric acid used as a local anesthetic. Gresch, May 2, 2006, 17:40 UTC

Is he sure he didn't mix up "cyclopropane"  with  "orthophosphoric"?68.231.189.108 (talk) 01:08, 30 October 2009 (UTC)

bone calcium deficiency
5. i have just finished reading a book about phosphorus and its compounds. from what i've read so far, calcium deficiency is not the main cause for the bone degeneration, but lack of phosphates.


 * I think this is useless scaremongering lacking in real scientific evidence. -- [[Image:Flag_of_the_United_States.svg|17px]]  Mac Davis ] ⌇☢ &#xE0D;&#x19B;. 04:26, 23 March 2006 (UTC)
 * Wait...this would imply that phosophoric acid would promote calcium uptake in the bones. This is contrary to other FUDing i have read/heard/etc. Where did you read this? --M1ss1ontom a rs2k4 (T 17:15, 1 November 2006 (UTC)

Reversion of anon deletions
Was that one of the above editors, accidentally logged out by timeout? The wiki syntax was messed up so I reverted, so I don't think it was a regular editor. - Leonard G. 05:34, 8 September 2005 (UTC)

melting point
This imho reliable source http://physchem.ox.ac.uk/MSDS/PH/phosphoric_acid.html gives a different melting point for phosforic acid (21C instead of 42C).

Acros, a big supplier of fine chemicals, also lists 21C on their website.

The same sources give also a different density (1.68 in stead of 1.9) and boiling point (158C vs 213)

Dispute
From what I understand the dispute seems to be over the effect of phosphoric acid on osteoporosis. The article cites few or no sources, so I'd like to add the following:


 * Wyshak G, Frisch RE. Carbonated beverages, dietary calcium, the dietary calcium/phosphorus ratio, and bone fractures in girls and boys. J Adolescent Health 1994;15:210–5.
 * Mazariegos-Ramos E, Guerrero-Romero F, Rodríquez-Morán F, et al. Consumption of soft drinks with phosphoric acid as a risk factor for the development of hypocalcemia in children: a case-control study. J Pediatr 1995;126:940–2.
 * Heaney RP, Nordin BEC. Calcium effects on phosphorus absorption: implications for the prevention and co-therapy of osteoporosis. J Am Coll Nutr 2002;21:239–44.
 * Brot C, Jorgensen N, Madsen OR, et al. Relationships between bone mineral density, serum vitamin D metabolites and calcium: phosphorus intake in healthy perimenopausal women. J Intern Med 1999;245:509–16.
 * Elmståhl S, Gullberg B, Janzon L, et al. Increased incidence of fractures in middle-aged and elderly men with low intakes of phosphorus and zinc. Osteoporos Int 1998;8:333–40.

But I am unfamiliar with citing practices for non-website sources. —Preceding unsigned comment added by Tzenes (talk • contribs) 14:34, 12 April 2006
 * Thanks for finding those citations, Tzenes. I have managed to look up a few on http://scholar.google.com and those I have seen so far seem to vary from disproving the claim (e.g. Heaney and Rafferty which suggests there is a moderate association with high caffeine intake but not with phosphoric acid), through to showing it to be the opposite of the truth (e.g. [http://www.springerlink.com/(tepiar553cj1icrreazllhml)/app/home/contribution.asp?referrer=parent&backto=issue,5,13;journal,125,175;linkingpublicationresult

One weak study involving only 30 women studied for the duration of a week does not trump all of those studies, even if it is mischaracterized as "a bunch of studies"

Use in soft drinks
Why is phosphoric acid used in soft drinks?

Norm

It's cheap, non-toxic, highly water-soluble, not too strongly acidic, and gives the kind of sour taste some people probably like. Citric acid, which has some similar properties, is also used in some soft drinks. H Padleckas 20:21, 25 June 2006 (UTC)
 * WTF? I thought it was to keep the caffeine dissolved in an environment in which it would otherwise crystallize out. --M1ss1ontom a rs2k4 (T 17:17, 1 November 2006 (UTC)
 * That is possible too. Caffeine is an amine which may not be very soluble in aequeous solutions unless it were neutralized by an acid to form a water-soluble ion.  Due to its non-toxicity, solubility, and moderate acidic properties, phosphoric acid seems like a good candidate for such a use.  H Padleckas (talk) 05:35, 2 June 2009 (UTC)

This article's got some poor wording. "the skeletal effects of carbonated soft drink consumption are likely due primarily to milk displacement."? Uh...Garbage. Even if the study *citing* it say s it, it's garbage. "Milk" is not necessarily a dietary staple.

Come to think, I'm a bit shocked we're even talking about studies by Pepsi. They're obviously in conflict of interest to the point of being unreliable. 216.14.79.3 (talk) 19:12, 12 August 2009 (UTC)Ubiquitousnewt
 * So remove it then157.203.42.175 (talk) 15:40, 4 February 2010 (UTC)
 * I came on here to say the same. I'd remove it, but I'm not dedicated to this debate enough to read all these studies to figure out the financier's bias. Clearly this section is being used as a debate forum making the content unreadable.
 * Also, milk is not a meant to be a part of our diet. The very reason the calcium content of milk drinkers' urine is higher is because most of the milk's calcium isn't absorbed into your body - even in adults with a healthy level of magnesium. A more typically-Japanese diet leads to greater overall mineral absorption. --173.16.183.58 (talk) 08:44, 30 July 2015 (UTC)

Quoting from the section "Biological effects on bone calcium and kidney health": "On the other hand, another study suggests that insufficient intake of phosphorus leads to lower bone density. The study does not examine the effect of phosphoric acid, which binds with magnesium and calcium in the digestive tract to form salts that are not absorbed, but rather studies general phosphorus intake.[4]". The rest of the articles focus on urinary products rather than digestive products. Would testing urine alone show a measurable precipitation of magnesium or calcium and phosphate salts if it happened somewhere in the digestive system? I thought you would require testing of more solid excretia. Is it possible the section could be summarized in one or two sentences and the rest thrown in discussion or put under more pertinent wikipedia article? There only seems to be one mention of relation to kidney health in the four paragraphs dedicated to "Biological effects on bone calcium and kidney health" and that was of calciuria. Is that to imply that if calcium is excreted via the urinary tract that you are more likely to get Kidney stones? If so, why not cite an article that says it rather than implying it. The lay reader, i.e., me, sees Kidney in the subtitle and expects to see a reference to kidney in the text indicating which part is pertinent to kidney health. Normally, debatable or unproven research results would not be included in an encyclopedia. If you have to imply it, then you probably have insufficient proof, ergo, not encyclopedic. I am not a chemist, biochemist or health professional so I will leave the editing to those with more qualification for editing. Added by Danny Robinson, New Zealand — Preceding unsigned comment added by 119.224.98.136 (talk) 00:23, 20 February 2012 (UTC)

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Orthophosphoric acid chemistry
In the final paragraph, this subsection discusses the dehydration of phosphoric acid. That phosphoric acid can be dehydrated by heating to metaphosphoric acid is supported by numerous references that I have found (though there is no mention in the article of the intermediate form of pyrophosphoric acid, which nearly every reference does mention). But the paragraph goes on to say that further dehydration leads to phosphoric anhydride (P4H10). This is, in a sense, true, since chemical dehydration of metaphosphoric acid will lead to this, but in the context of this sentence, it suggests that further heating would cause further dehydration. I can find no reference to support that -- indeed Merck 9th ed. says that metaphosphoric acid volatilizes at red heat. Hence it would be well nigh impossible to dehydrate metaphosphoric acid by heating. Karlhahn 14:21, 23 September 2006 (UTC)
 * There is the tendency to assume that heating many acids will cause dehydration, and this assumption might have crept into this article. A start in figuring out the facts would be to go beyond the Merck Index, which is bascially a handbook for physicians. I have been rewriting P4O10 article and have relied on Corbridge:

What you are looking for might be difficult to find. I recommend deleting the paragraph that you suspect is misleading and re-writing it based on the facts known to you.--Smokefoot 15:01, 23 September 2006 (UTC)
 * D. E. C. Corbridge "Phosphorus: An Outline of its Chemistry, Biochemistry, and Technology" 5th Edition Elsevier: Amsterdam. ISBN 0-444-89307-5.


 * I don't own the book you cite, so I hope you will let me know if somewhere it answers the question. For now I will do as you suggest, and then wait for such time as you can clarify the issue. Karlhahn 22:52, 24 September 2006 (UTC)

You can get futher dehydration of some of the acid salts of phosphoric acid by heating: this is used to make superphosphate fertilizers. From vague memory, I think that metaphosphic acid is the limit for dehydration of the free acid, but, even disregarding the vagueries of my memory, the experimenters may well have missed higher acids (I bet no-one has looked at the question for several decades). I would look and see what you can find on superphosphates, that may give an idea of what happens to the free acid. Physchim62 (talk) 13:21, 25 September 2006 (UTC)


 * I looked up monobasic sodium phosphate (NaH2PO4). On heating it loses all water and becomes sodium metaphosphate (NaPO3)n. I can find no source that this decomposes on further heating. I suspect, though, that if it is heated enough while mixed with SiO2 to absorb the sodium, you could, conceivably, distill P4O10 from the glassy melt. I don't know this for sure, though. Karlhahn 12:51, 26 September 2006 (UTC)

if not heating
Will elèctròlusis work? -lysdexia 14:05, 10 October 2007 (UTC)

Le Chatelier's principle
Whoever thought this supported their claim was very wrong.

Here is the reaction of Phosphoric Acid with Calcium:

2 H3PO4 + 3 Ca(OH)2 -> 6 H(OH) + Ca3(PO4)2

According to Le Chatelier's principle, if you add more H3PO4, it pushes the reaction to the right which consumes more calcium.

According to Le Chatelier's principle, if this reaction consumes unbound calcium in the digestive tract, more will be freed from the bone.
 * This is the correct application on Le Chatelier, not the one above mDonaldson 03:56, 15 January 2007 (UTC)

The above assumes that bone is in equilibrium with the digestive tract, which is far from the case... It also assumes only two species, also incorrect. Physchim62 (talk) 10:32, 15 January 2007 (UTC)

Studies
This article seems to hold a bias in support of Tucker et al. I would recommend presenting Tucker as a counter study to Elmstål, removing the exhaustive discussion of Tucker (from "This is Tucker..." to "...needed to confirm the findings." and leaving it as a reference as is done for the other studies. This discussion is redundant to the citation and biases the article toward this study by presenting it is a more dignified manner. "This is Tucker..." is akward syntactically. mDonaldson 03:56, 15 January 2007 (UTC)

Add Image
What do you think about this image? Should it be added to "Preparation.." section? Abelin  C A  usesobad  07:17, 17 January 2007 (UTC)


 * Looks like you took this picture directly from this website:


 * As such, it might be copyrighted, and if so, we can only use it with the explicit permission of the author. Besides, as this pic was uploaded, it is a large detailed diagram in a *.gif file.  The *.gif file format makes it unsuitable to be resized on Wikimedia web pages.  For example on this web page, here it looks highly illegible to me.  In the past, I have converted a couple of similar *.gif diagrams into *.png files and uploaded them for improved legibility and some minor editing, but because of the copyright issue, I do not find it worthwhile for me to do so with this pic at this time.  H Padleckas (talk) 03:15, 25 May 2009 (UTC)

used as a denture cleaner / whitener
My mom wants to replenish an old bottle of Dent-U-Care denture cleaner.

It states on bottle "WARNING" "contains phosphoric acid" as the only listed ingredient.

My search produced 2 red flags:
 * dentucare.com webname, Deleted, May 27, 2007 (no further info)
 * "Dentucare UK. The Smile Centre. White Teeth In 45 Minutes.    Unfortunately, a few of mine have already fallen out."

any input on this appreciated

--Mamatops 22:30, 13 September 2007 (UTC)

possible picture?
Is Image:Luc Viatour phosphore poudre.jpg a picture of phosphoric acid? Calliopejen1 21:27, 15 September 2007 (UTC)


 * No, that's white phosphorus.


 * Ben 23:16, 15 September 2007 (UTC)

Empty?
Why it is called orthophosphoric acid instead of phosphoric acid? Can anyone give me th answare? Thanks


 * Both are names for H3PO4. But there are many other oxoacids of phosphorus in the +5 oxidation state, and these are collectively known as phosphoric acids - see the article Phosphoric acids and phosphates for a list. Any single member of this group of compounds can therefore be called a phosphoric acid. So to distinguish between one of these compounds and H3PO4 itself, the prefix ortho- is sometimes used.


 * Ben (talk) 11:39, 2 August 2008 (UTC)

Calcium removal debate
Is this really even appropriate for this article?

I mean, a mention of possible health effects is alright, but is this long (dubiously researched) passage on whether or not your bones will melt if you drink soda necessary? Jgr2 (talk) 16:28, 25 March 2008 (UTC)

I'd say it's valid. That's the reason I looked this article up. The alternative would be for this article to have a link to a separate article that talks about that. 71.92.101.14 (talk) 05:12, 28 October 2009 (UTC)

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pKa data
Which source is correct? Sigma-Aldrich is quoting different pKa values at 25oC (for K-phosphates)

(1) 2.15, (2) 6.82, (3) 12.38 (phosphoric acid)

http://www.sigmaaldrich.com/catalog/search/ProductDetail/SIGMA/P8416

I've also check the Handbook of chemistry and Physics 52nd edition (1971-1972) which gives 2.12, 7.21, 12.67 -same as those used in this article- so I assume the values here are from the handbook. The infobox refrences should be made clearer.

I'm inclined to trust Sigma-Aldrich as theirs are probably more recent. I guess it must be different for differnt salts (e.g. just the phosphates (aq) for kotassium phosphate salts, ammonium salts, sodium salts etc) But i don't see how they can differ so much?

There were no error values in either source - "values without error-bars are like products without brand-names!"

—Preceding unsigned comment added by 129.11.62.201 (talk) 13:50, 18 August 2008 (UTC)

There's actually inconsistencies between the Ka values listed in the equations and the corresponding pKa listed in the succeeding paragraph. I'm inclined to believe the values in the paragraph since it matches the values on the phosphate page, but would anyone like to confirm? Seraphchoir (talk) 21:10, 25 February 2013 (UTC)

The dissociation constants and pKa values are both provided by old editions of the CRC Handbook, as per the reference I have added. The newer editions (since the 74th) supply different pKa values and even give a reference for their data, but do not give values for the dissociation constants themselves. To avoid a technical WP:OR issue I have stuck with the old values, but if others feel more comfortable with supplying manually-calculated values the most recent CRC Handbook (96th ed.) gives pKa as 2.16, 7.21, 12.32. 130.216.208.173 (talk) 04:55, 14 March 2016 (UTC)

Another strange formula..
What's up with these formulas??

"3NaCl(s) + H3PO4(l) -> NaH2PO4(s) + HCl(g)

3NaBr(s) + H3PO4(l) -> NaH2PO4(s) + HBr(g)

3NaI(s) + H3PO4(l) -> NaH2PO4(s) + HI(g)"

Does those two remaining units of halide-salt somehow go up in smoke and disappear from the universe? In these "reactions" they seem to do just that.

The only way I can think of to make sense of this is to view it as that it says that only one unit of salt can react and create a hydrogen halide despite the acid having 3 hydrogen atoms. (Which may not even be true) But you can't really put 3units in a formula describing a reaction if 2 of them actually don't take any part in said reaction....

Who wrote the formula(s), and what was it intended to mean? Or was it simply copied from some obscure & unreliable internet site without any verification whatsoever? —Preceding unsigned comment added by 90.227.181.98 (talk) 15:47, 23 August 2008 (UTC)

Rust removal
I think some redistribution of text between Rust, Rustproofing and Rust removal is needed. Biscuittin (talk) 16:25, 22 May 2009 (UTC)
 * I suggest that Rustproofing be re-named Rust prevention and removal and that "Rust removal" (which is currently part of the phosphoric acid article) be merged with it. Biscuittin (talk) 22:21, 23 May 2009 (UTC)

What is it made from
What is food-grade phosphoric acid made from and how is it made? The article says it is a "mass-produced chemical" but no indication is provided as to how it is produced and from which materials. Badagnani (talk) 23:49, 30 August 2009 (UTC)


 * Not true, see Thermal phosphoric acid. Pyrotec (talk) 12:43, 31 August 2009 (UTC)

Photo
Can we get a photo of the actual acid? Badagnani (talk) 05:40, 28 November 2009 (UTC)
 * Yes possibly someone could do it, but 85% phosphoric acid is a clear, colorless liquid, and a photo would look like just a container of water. H Padleckas (talk) 16:21, 29 November 2009 (UTC)

Naval Jelly
Should there be mention of the fact that Phosphoric Acid is also known as "Naval Jelly"?

216.146.231.6 (talk) 23:22, 19 October 2015 (UTC)Dave
 * Naval jelly is not a synonym for phosphoric acid. -- Ed (Edgar181) 23:33, 19 October 2015 (UTC)


 * "Naval Jelly" redirects to this page, but is not mentioned on the page. If it's going to redirect here, seems like it should at least be mentioned in the body of the article.  Else there should be a separate article for "Naval Jelly".
 * 70.89.176.249 (talk) 20:43, 7 January 2020 (UTC)

"Tricalcium phosphate rock"

 * There is no such thing. "Apatite" is a group of minerals being PENTAcalcium TRI(ortho)phosphates. Ca3(PO4)2 is extremely rare in nature.Eudialytos (talk) 19:26, 29 May 2017 (UTC)

Enamel Decay
Please add the following to the Wikipedia page for Phosphoric acid.

In 'Uses' on the end of the 'Food Additive' section

"Phosphoric acid has also been linked to decay of tooth enamel, due to its low PH."

Here is the relevant reference to substantiate the claim.

http://www.nature.com/bdj/journal/v193/n10/full/4801628a.html — Preceding unsigned comment added by 92.14.180.33 (talk) 19:42, 29 June 2017 (UTC)
 * I've done something similar: . --jpgordon&#x1d122;&#x1d106; &#x1D110;&#x1d107; 19:55, 29 June 2017 (UTC)

Thanks Jpgordon, Dan — Preceding unsigned comment added by 92.14.180.33 (talk) 20:01, 29 June 2017 (UTC)

Did you know?
Although isn't a strong acid, it can dissolve tungsten. 80.98.179.160 (talk) 19:16, 27 March 2018 (UTC)

Chembox entry E number
The correct E number is E337 (not E338 and definitely not an antioxidant. How can this error be corrected? I can't find "E number" in the article text for the chembox. Petergans (talk) 08:15, 13 August 2018 (UTC)

The E number is E338 as per ref 13 & Wikipedia's list of E numbers. Its function is usually acid. I can't figure out how to revert the change! MGSpiller (talk) 15:29, 11 October 2018 (UTC)