Talk:Sulfuric acid

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Contents

[edit] Various notes with no title

Question: How can I add the Critical Point of Sulphuric acid (925 K @ 6.4 MPa)? —Preceding unsigned comment added by 124.186.72.24 (talk) 20:36, 18 January 2008 (UTC)

The {{Chembox properties}} template does not currently have a field defined for critical point (temperature or pressure). This is because this level of data usually goes onto a separate data page for the chem in question (see Ethanol (data page)) as an example. Sulfuric acid currently has a data page, but it is sparse. But if somebody wants to improve it, please see other chem data pages (see category:Chemical data pages for a list of them) so that you can follow the model already in place. Karl Hahn (T) (C) 22:08, 18 January 2008 (UTC)

Does anyone think it would be a good idea to include CAS Number in the box?

1 Oleum is not a solution of SO3 in aqueous H2SO4, that would make it just H2SO4. it is SO3 dissolved in pure H2SO4. By destillation (nasty stuff, watch out) the pure SO3 can be obtained. It becomes solid after a while.

2. The body does metabolize sulfur by oxidizing it, but as such the line is a bit misleading, no? The solution in your bodu is buffered of course.

Somebody put me right but I think Oleum is H2SO7? Rjstott Actually it is a solution of SO3 in aqueous H2SO4. --rmhermen See oleum - verified contents.--Forschung 10:02, 21 Dec 2004 (UTC) ==:Oleum - H2S2O7 -x42bn6 Talk 01:16, 3 October 2005 (UTC)


Question - does the Wikipedia use American or British spelling? If it uses American, then the element S should be sulfur, not sulphur (and similar for sulfuric, sulfurous, etc) -- Marj Tiefert

Simple answer: Yes.
We here at wikipedia have, Yanks, Brits, Australians, Kiwis and even people from some other English speaking countries. So we don't officially endorse any system of spelling -- so long as the word in question is spelt correctly in at least one widely used dialect of English. --maveric149

Thanks ;-)
I suppose it would be too much trouble to change all the page names anyway... -- Marj Tiefert

On the other hand, it seems that alumin(i)um has pretty much settled down to the UK spelling (as much as anything on a Wiki is settled), on the grounds that aluminium is the spelling recommended by IUPAC since 1990.

Also since 1990, IUPAC has recommended sulfur as the spelling of this element. The Chemical Abstracts agree, and since 1992, even the Royal Society of Chemistry has had sulfur as its official nomenclature recommendation (although not all RSC publications follow this recommendation). And as of this writing, the element itself, as well as most of its compounds that have their own page, use the 'f' spelling in the Wikipedia.

So, I'm highly inclined to make this page sulfuric acid and the redirect sulphuric. -- user:Shimmin

       I second this motion, the IUPAC names should always be used when naming 
       chemicals here.

       P.S. The only reason I changed everything to sulphur* was because
               1) I hadn't realized that the IUPAC standardized on one
               2) Before the change, the article was a horrible mish-mash of
                  sulphur and sulfur. Considering the article was titled  
                  "Sulphuric acid", I felt it best to use that.
               
                  Darrien 16:28, 2004 Mar 18 (UTC)


Actually, I come from the UK, and I was always taught at school that it should be spelt with an F, even though the original "British" English version is with PH.

You American editors are going to hate me for this but with all due respect as a Chemist (im studing my A-Levels) and have found out that Sulphur is the internationally recognised wording therefore can one of you changed this title to be internationally recognised variant.

You are mistaken. See Wikipedia: Naming conventions (chemistry). Shimmin 15:12, 5 November 2005 (UTC)
Shimmin is quite right. I got an A in my A-levels (and a Grade 1 S-level) in the UK in 1978, I now hold a Chemistry PhD, and I have worked in chemistry all of my life. IUPAC ruled on this a few years ago (see above). Even the Royal Society of Chemistry spells sulfur with an f now (see here for an example. On chemistry pages we try to follow IUPAC. With A-level chemistry you should be able to make some good contributions to the chemistry (not the spelling!), come & help us! Cheers, Walkerma 18:06, 5 November 2005 (UTC)

Erk, saved changes in wrong window. Thanks for the revert, Tarquin. -- Roger, 16:34 UTC, 1 Sep 2003

lol. no problem! -- Tarquin 17:36, 1 Sep 2003 (UTC)

This isn't very encyclopedic, but I thought it would be fun to mention somewhere in the vicinity of the article - a mnemonic, of sorts, for young chemists:

Johnny was a good boy, [or "...chemist"]
But Johnny is no more,
For what he thought was H2O,
Was H2SO4!

:-D IMSoP 23:06, 7 Apr 2004 (UTC)

Er ... did you read the article? Make sure you go to the bottom. - DavidWBrooks 22:35, 7 Apr 2005 (UTC)

"In 1746 in Birmingham, John Roebuck began producing sulfuric acid ... the standard method of production for almost two centuries."

Yet there's a new process invented in 1831. 85 years is barely close to one century, nevermind two. Is that 1646?--Eric 6 July 2005 18:47 (UTC)

The contact process was invented in 1831, but was not used on any great scale until the late 19th century, and didn't overtake the old route in terms of volume until the 1920s. Shimmin July 7, 2005 21:11 (UTC)

[edit] keep "Vitriol" as a separate entry

As a writer, the phrase "To hurl Vitriol" is useful, and it is useful to be able to easily look up the origins of the word.

Vitriol seems to have a greater historical context. With a simple link from page to page one can easily see that both compounds are the same and leave historical context of vitriol intact.

  • I agree. I have removed the suggested merge. Physchim62 15:20, 16 October 2005 (UTC)

I'm re-suggesting the merging of the two articles, to a point: the information about the history and chemical composition of sulfuric acid is already covered on the sulfuric acid page. There is the point about the phrase "to hurl vitriol", but Wikipedia is not a dictionary. The vitriol page should remain, but should focus on information pertinent to the word itself, perhaps including a bit about the fake alchemy acronym, and its use in alchemy - but all the duplicated info should just be replaced with a link to sulfuric acid. Pjrich 03:22, 13 December 2005 (UTC)

I don't understand why any information about word history etc. should go in Wikipedia rather than Wiktionary. Dictionaries aren't just about defining things. --Dfeuer 02:24, 25 January 2006 (UTC)
Wiktionary's "vitriol" entry does have an etymology section, so that's already covered, but areas such as cultural history don't seem to be normally adressed in Wiktionary. Barring massive public outcry I'll remove the merge and just tidy the two articles up a bit as suggested so there's less overlap. Pjrich 20:42, 3 February 2006 (UTC)
Maybe it would be best to talk to the high poobah Wiktionarians and get their input on the matter. Dfeuer 20:59, 5 February 2006 (UTC)
I doubt you'll get the high poobah to visit here. But I think what Pjrich said was accurate. We don't currently do word histories on Wiktionary. That doesn't rule out the possibility of doing them someday. Some support the concept in theory, but we do not have any place right now for them. It's not likely to happen very quickly, so hang onto the information for us, for now. --Connel MacKenzie 17:47, 12 February 2006 (UTC) Wiktionary sysop. (Previous statement rewritten.)


The rhyme used in colleges across the world today goes as follows: Johnny was a Chem student, but Johnny is no more, For what Johnny thought was H20 was H2SO4. ALSO: Sulphuric Acid is VERY DANGEROUS and it is common college practice to wear gloves and safety goggles, as well as closed in shoes, hair tied back if it is long, and a lab coat, at all times of handling. DO NOT DRINK OR WASH HANDS IN H2SO4. DO NOT TRY TO CLEAN YOUR CONTACTS WITH IT. IN FACT, WEAR A WHOLE BODY SUIT AND GAS MASK WHEN IN THE RANGE OF 25 METRES OF A FLASK OF SULPHURIC ACID. EXTRATERRESTIAL H2SO4 COMES IN PEACE. Over to you Charlie.

[edit] Sulfuric Acid Drain Cleaners

Please maintain a neutral POV on this page related to the sulfuric acid drain cleaner question. Whether or not sulfuric acid drain cleaners should be banned for sale to the public is currently being debated on the federal level, and is discussed in the drain cleaner article.

[edit] bicarbonate of soda

We now have conflicting advice about what to do in case of acid burns - keep bicarbonate of soda handy, but don't use it! This needs to be cleared up - or (my preference) the whole advice portion of the article eliminated. Wikipedia isn't a safety manual. - DavidWBrooks 10:55, 27 October 2005 (UTC)

  • It's not conflicting. Sodium bicarbonate is useful for acid spills, so long as they are not on the skin. Physchim62 11:03, 27 October 2005 (UTC)
    • Ah, I see. I rearranged the paragraph slightly to help other people from being as confused as me. - DavidWBrooks 12:53, 27 October 2005

(UTC)

    • Um no. A solution of Sodium Carbonate or Sodium Bicarbonate will neutralise acid on the skin and thus prevent damage.
  • Thanks. I would have done it myself, but I was in the middle of a long series of edits after a page move. Physchim62 13:49, 27 October 2005 (UTC)

[edit] Comic rhyme (again)

It seems that many people think that this encyclopedia would be incomplete without this rhyme. While I think it shouldn't be here at all, I think I could put up with it. However, do we need four versions of it (and more to be added in the future)? If it's that important in popular culture, we need a separate article entitled Comic rhymes about sulfuric acid. I propose to delete all but one from version this article, and include a comment that "many variations exist." Does anyone want to present a case against deletion of variants? Walkerma 17:50, 11 January 2006 (UTC)

I have removed variants in the past, as well; they keep returning. Still, I think it is good for the article, since a good chunk of the population knows nothing about the acid except this rhyme, which is one of the few, if only, bits of popular oral culture built around a chemical formula. Personally, I think the UK and US variants are sufficiently different to both be included (just one of each), but perhaps that just opens the door to multiple versions; I wouldn't balk if we cut it down to one. (But which side of the pond will be left out?) - DavidWBrooks 18:47, 11 January 2006 (UTC)
I agree with keeping one, given that it is obviously a popular culture issue to some editors. I say keep an American version, preferably one for which we have some info as to its first recorded (Pre-Wikipedia) use: I have never personally come accross such rhymes on the European side of "The Pond", but that doesn't mean that they don't exist! Physchim62 (talk) 16:16, 14 January 2006 (UTC)
I've never been sure that the labelling of the variants we have as "American" and "U.K." was indicative of anything other than the nationality of the contributors that added them, as the variant I learned in my (U.S.) chemical education is
Little Johnny was a chemist
Little Johnny is no more
For what he thought was H2O
Was really H2SO4
Shimmin 00:04, 28 February 2006 (UTC)
I second the motion for an article devoted to comic rhymes about sulphuric acid. Horst.Burkhardt 09:14, 20 August 2007 (UTC)

[edit] Nationality of Jabir Ibn Hayyan

158.39.34.35 recently changed the nationality/ethnicity of Jabir Ibn Hayyan in this article from Arab to Iranian. According to the article about him, Ibn Hayyan was born in Iran but moved to Iraq. That article places him in the category "Arab Chemists" but does not describe him anywhere as Iranian. I hope someone more familiar with Wikipedia conventions can determine the correct description. Furthermore, the main article on Ibn Hayyan is named Geber. Should this reference be changed to match? Dfeuer 20:05, 11 February 2006 (UTC)

I also noticed this at the time, but the books I had didn't help. A web search also left things ambiguous. The probably with famous people is that everyone wants to claim them as one of their own! I have a book at home (now in the attic) on "The History of the Arab Peoples" (yes, chemists do read history) and I seem to recall that the Persians of that time were included as Arabs, certainly the Samanids were. According to Wikipedia the earlier Sassanid Empire was defeated by (you guessed) the Arabs, who brought Islam. So I think that Geber was BOTH Arab AND Iranian/Persian. Walkerma 23:39, 27 February 2006 (UTC)
The nationality and where abouts can stay in the articles of the persons and not in the article of sulfuric acid. There are several french and german scientists mentioned on the page without giving them the atribut born in where ever everytime they are mentioned. The Islamic or Arabic is another thing. Islam is a religion and if this is found in a religious book its Ok, but if this was found in a scientific book the language in which is written is the atribute to be given. arabic persian sanscrit or what ever. Arabic was bevor but may be its written in persian tahn change it to persian or what ever, but islamic alchemist would be as wrong as christian chemist.--Stone 11:47, 4 April 2006 (UTC)
The nationality of these individuals should stay, it's significant. --ManiF 11:56, 4 April 2006 (UTC)
Jabir may be the most troublesome can of worms in classical Arabic. One school of textual criticism would make him a sort of 9–10th century Nicolas Bourbaki. Shimmin 12:15, 4 April 2006 (UTC)


A quick look in Britannica [1] or Columbia Encyclopedia [2] , and all major Encyclopedia's would tell you that he is an Arab. Jidan 14:41, 4 April 2006 (UTC)
There are conflicting sources about his ethnicity, but he's defiantly Iranian-born as per your own sources plus the evidence and discussions on Talk:Geber. Don't remove a factual statement. --ManiF 14:54, 4 April 2006 (UTC)

Hi, I am not aware of the nationality of Geber, but I strongly feel that mentioning his country of birth is more important than his religion. From a quick browse around, most scientists in their own pages have their coutries listed, and none I found had a religious connection made explicit in the first few lines. If you really can't agree on where he came from, I think nothing would be preferable than "islamic." -postglock 08:20, 3 May 2006 (UTC)

[edit] Need citations

"Is credited to" and "is sometimes credited" need to cite sources. Dfeuer 20:11, 11 February 2006 (UTC)

[edit] Links, sulfur and fertilizer

The article now has consistent spelling of sulfur and fertilizer. The article had both American and British spellings. Aluminium was already consistent with other instances of it, even though the rest of the article uses American spelling. I don't mind and I believe it is the preferred scientific spelling internationally.

I removed a lot of redundant links. There were multiple links of some words in the same section, and sometimes in the same paragraph. I left links that were used in other sections since it is a long article. -- Kjkolb 02:34, 19 April 2006 (UTC)

Thanks for the cleanup. Sulfur is now the preferred spelling for British chemistry usage (e.g., the Royal Society of Chemistry uses it), because it is the IUPAC approved name. Aluminium is likewise the IUPAC name, and the American Chemical Society should be using it (as with caesium)! Walkerma 04:24, 19 April 2006 (UTC)

[edit] pKa

Why are there two values for the pKa? -postglock 05:09, 30 April 2006 (UTC)

Sulfuric acid is a diprotic acid. The lower value is for losing the first H+ to form HSO4−, the higher pKa (less acidic) value is for this ion (bisulfate) losing another H+ to form SO42−. Walkerma 05:25, 30 April 2006 (UTC)

Thanks for that, Walkerma. Do you think this is pretty obvious to most people (I suppose it is in retrospect); it shouldn't require clarification in the box? -postglock

There is mention of these equilibria under Sulfuric_acid#Reaction_with_water, but no mention of pKa there. I'm heading to bed now (3am local time!) but I'll try and improve the box tomorrow, and maybe look at others like phosphoric acid too. Thanks for the comment! Walkerma 07:05, 30 April 2006 (UTC)

Hey Walkerma, or anyone else, wondering if you had any thoughts on how to do this? I thought about "1st proton" and "2nd proton," but it looked pretty ugly. Any suggestions? or is it even necessary? -postglock 09:25, 26 May 2006 (UTC)

For polyprotic acids you have pKa1, pKa2, etc, so on the left column you should have these instead of just pKa. However I am not sure whether the value for pKa1 (-3) is correct. I raise this issue below (topic # 14). I have found conflicting sources, some in favour of -3, some in favour of -9 or -10. It is quite important to clarify this, since you need the value in order to compare the strength to other acids. E.g. HCl according to the wikipedia link has pKa=-8. If we accept the original pKa1=-3 then sulphuric acid appears as a weaker acid. If we accept the other (-10) then sulphuric is stronger.--84.254.23.155 20:26, 22 December 2006 (UTC)

I am inclined to go with the -10 pKa1 value. Not only have I never heard of a -3pKa1 value, but -10 simply makes much more sense. Sulfuric acid is stronger than hydrochloric, as evidenced by the higher degree of dissociate it exhibits. -Eric

[edit] Jabir ibn Hayyan

Lets agree on NO mentioning of ethnicity or nationality. ITS TOTALLY IRRELEVANT to this article. @ManiF, I know you like this ethnic-crap,your history proves that. But lets leave your ethnic-war hobby at Jabir main article,not here, shall we? jidan 10:57, 3 May 2006 (UTC)

His place of birth is relevant information, don't remove it. --ManiF 11:00, 3 May 2006 (UTC)
We can mention both, his place of birth and ethnicity, so it will be: iranian-born arab alchemist ... . But mentioning one without the other will not work. And at that time Tous(his birthplace), was part of the arab empire not Iran. I would favour removing all that ethnic-crap, since its irrelevant to this article.jidan 11:08, 3 May 2006 (UTC)

This is not a history article, his place of birth would it, his ethnicity is disputed. --ManiF 11:12, 3 May 2006 (UTC)

I tried this:His ethnic background is not clear; although most sources state he was an Arab (which he was by Jus sanguinis), some claim he was Persian (which he was by Jus soli). but his ethnic is disbuted as well so this also will not work. If anyboy is really interested if the arab empire was or was not where he lifed or if his ethnic status was or was not arab or persian, should read the main article! The only thing I wanted to state is that islamic is not a good solution. If I change the english biologist Charles Darwin to the christian biologist Charles Darwin (in fact he was a religiuos man!), the impression everybody would get that his religious status had a big influence on his research.--Stone 11:27, 3 May 2006 (UTC)

Iran at that time didn't exist. It was Arab soil, and a province of the arab empire. And jabir's parents were aborignal arabs from the arabian peninsula. @Manif: This has nothing to do with Sulfuric acid, why dont u get it? If a user is interested in knowing more about jabir's life, he will check his main article. Your motive's are purely nationlastic, as can be seen from other articles you edited. jidan 11:30, 3 May 2006 (UTC)
@Stone: I know what u mean. But Islamic in this sense is not a relgious term, its a chronological term. All scientists that lived within the arab caliphate, were called just islamic scientist, although some of them were jews and christians. All those scientsist have in common that they wrote in arabic, and did thier work in the baghdad, the capital of the arab caliphate. jidan 11:34, 3 May 2006 (UTC)
Just because the land was occupied by Arabs at that time, doesn't mean Persia or Iran didn't exist. That's like saying Poland didn't exist in 1940's because the Nazis had occupied it. Regardless, no one is mentioning ethnicity or nationality, these discussion have no place here, Jabir was born in Tus and place of birth is a relevant information, don't censor it. --ManiF 11:43, 3 May 2006 (UTC)
The Poland argument would bring me to the point making some people born in europe between 1939 and 1945 germans, would be a fun to try. The uprise you would generate would be nice to see. And best you can modify even the biography of living people. They will be get relly angry beeing german by Jus soli. But for know occupation terretory or part of the country or even better freedom fighters or terrorists is a discussion which never will stop, and has no solution.So lets have the place of birth or not, but the real war should be on the Geber main page and be solved there.--Stone 12:32, 3 May 2006 (UTC)
I agree with you Stone, this is what I said since the beginning. The war should be in Geber page. I still dont get what Sulfuric acid has to do with this. jidan 18:35, 3 May 2006 (UTC)

Jabir left Tous,Khorasan(at that time an arab province) in his childhood after his father got executed. He then moved to yemen, the home country of his parents[3].There he learned to read and write. He lived most of his life in Kufa(Iraq) and Baghdad(Iraq) and wrote all his works in Arabic. So, by culture,nationality and by blood, he is an Arab. Because its irrelevant in this article, any mention of his background will be removed. jidan 10:11, 4 May 2006 (UTC)

No, there is nothing certain about his culture, nationality and blood. Not much known is about his life expect that he was born in Tus which is a fact you are trying to censor, everything else about his life and background is disputed by contradictory sources. --ManiF 00:38, 5 May 2006 (UTC)

The French translator of an old edition of Sprenger's 'History of Medicine', seeing the name Geber, assumed he was German and rendered it 'Le Donateur'(giver). Geber himself, an alchymist and sufi, would likely have dismissed the matter discussed above as an amusing and artificial irrelevance.

[edit] Dilution

How can you work out how hot a solution will become when diluting sulfuric acid? Eg. 98% -> 20%, how much energy will be given off?

Thanks very much

210.246.0.84 04:28, 21 June 2006 (UTC)

[edit] References

Could we get just a little bit more references? The article is close to FA status, it just needs more inline citations and a consistent referencing system. Titoxd(?!?) 05:19, 13 July 2006 (UTC)

[edit] IUPAC recommends "Sulphuric acid" or "Sulfuric acid"?

Which does IUPAC recommend? --HappyCamper 16:48, 10 August 2006 (UTC)

I think sulfur in stead of sulphur, so sulfuric acid, and so for all compounds which have the word sulfur/sulphur in the name?
By the way, is it an idea to put all those spelling things into one document (e.g. IUPAC recommended spelling of substance names) or something similar, and making a link there on top of the page (like a {{for}} or {{see also}}, e.g. {{alternative substance naming}} with parameters sulphur and sulfur on the sulfur page, redirecting to a subheader on the naming page). It would make life easier on which policy the chemistry part of Wikipedia has adopted for pagenaming (if a dispute, make a link in the first line to that document). And in that way we can eradicate all spelling-sections. With a bit of careful thinking it could even be used for pages where systematic naming vs. trivial name is a problem. --Dirk Beetstra T C 17:09, 10 August 2006 (UTC)
Let's bring this up on Wikipedia:WikiProject Chemistry. I think expanding this idea might be useful. --HappyCamper 17:17, 10 August 2006 (UTC)

(copied to Wikipedia_talk:WikiProject Chemistry --Dirk Beetstra T C 17:34, 10 August 2006 (UTC))

Basilius Valentinus is "backronym". What does it signify?

Some equations regarding oxidation of iron by sulfuric acid are a bit on the dodgy side; e.g. Fe3+ being rendered as Fe+++ - should we fix these up? LudBob 09:23, 5 October 2006 (UTC)

[edit] pH of sulfuric acid solution for different concentrations

Dear authors, the article says: < ...Some common concentrations are:

10%, dilute sulfuric acid for laboratory use (pH 1) 33.5%, battery acid (used in lead-acid batteries) (pH 0.5) 62.18%, chamber or fertilizer acid (pH about 0.4) 77.67%, tower or Glover acid (pH about 0.25) 98%, concentrated (pH about 0.1) Since sulfuric acid is a strong acid, a 0.50 M solution of sulfuric acid has a pH close to zero ... > 0.5M solution gives 100*0.5 gram/L or about 5% w/w concentartion. How 0.5M can give pH~0 while 10% gives 10 times weaker pH=1? IMHO all pH values in the table are improper 72.56.180.181 19:03, 30 October 2006 (UTC)Coca

Sulfuric acid is not completely a strong acid. It is a strong acid for the loss of the first proton, but weak for the loss of the second proton (pKa = 1.99). A 0.5 M solution has a calculated pH of about 0.3: however, at these concentrations (and anything more concentrated), you really need to take account of activity coefficients. That having been said, the vaules in the article look pretty suspect, to say the least. Physchim62 (talk) 08:22, 31 October 2006 (UTC)

Can we be more rigorous about our use of % here, and change it to %w/w? —Preceding unsigned comment added by 136.142.83.168 (talk) 19:22, 2 January 2008 (UTC)

[edit] pKa1 value

The pKa1=-3 given must be wrong. I have come across websites where it is -9 or -10

and these values are more reasonable when considering that for HCl pKa=-7 or -8. H2SO4 is a stronger acid than HCl (pKa1 should be lower than pKa of HCl) since O is more electronegative than Cl, O is also bound to other electronegative atoms (induction effect) and there is a resonance structure stabilizing even more the conjugate base (the anion). —The preceding unsigned comment was added by 84.254.23.155 (talk) 11:27, 22 December 2006 (UTC).

Disagree. It should be noted from the start that it is very difficult to measure such low pKa values, so some differences between sources are to be expected. Sulfuric acid should have a pKa value between those of phosphoric acid (2.1) and perchloric acid (−7). The most important inductive effect is that of the central atom, which can either attract electrons from the oxygens or supply electrons to the oxygens, depending on its electronegativity. The order of electronegativity is Cl > S > P, hence the chlorine atom in perchloric acid has the greatest tendency to attract electrons from the oxygens. As it attracts electrons, the oxygen atoms become less negative in charge, and so have less attraction for the hydrogen ion. This leads to a greater acidity (compare, for example, the acidities of trichloroacetic acid and acetic acid).
Note that electronegativity depends on oxidation number: the higher the oxidation state, the more electronegative the atom. I have assumed that the chlorine(VII) centre in perchloric acid is actually more electronegative than the oxygens, but this is not necessary for the argument: all that matters is the order of electronegativities, which shows that perchloric acid should be more acidic than sulfuric acid, and phosphoric acid less so. This PDF file give a large compilation of pKa values with references (and conveniently agrees with −3 for sulfuric acid! ;) Physchim62 (talk) 14:00, 22 December 2006 (UTC)

I agree on what you say for trichloroacetic and acetic acid. The first is stronger than the second because of the inductive effect of the chlorine atoms. That's exactly one reason why I would expect H2SO4 to have lower pKa1 than the pKa of hydrochloric acid. O is more electronegative than Cl, plus S and the other oxygen atoms would pull the electrons even more because of the inductive effect, like the Cl in trichloroacetic acid.
You also have resonance structures stabilizing the anion which should decrease the pKa1 even more.
I saw the pdf you are referring to and the irony is that in one of the links I am providing in the first post they provide the same pdf for values other than the one they show on their table. Nonetheless I have found (apart from the 2 above links) one more http://www.uaf.edu/chem/321Fa06/pkas.html where pKa1 of sulphuric acid is higher than the pKa of HCl. The reference for the pKa in that case is from E. P. Serjeant and B. Dempsey (eds.), Ionization Constants of Organic Acids in Solution, IUPAC Chemical Data Series No. 23, Pergamon Press, Oxford, UK, 1979. which is more recent than ref 28 that is mentioned in the pdf file (Kolthoff, Treatise on Analytical Chemistry, New York, Interscience Encyclopedia, Inc., 1959.). Unfortunately I don't have access to either of the original references but one of them must be wrong.Do you have any means to clarify which is accurate?--84.254.23.155 17:21, 22 December 2006 (UTC)

That latest link that you quote illustrates another point very nicely: namely that electronegativity is not the only factor in acidity. If you look at the acidities of the hydrogen halides, you will see that HF << HCl < HBr < HI, exactly the opposite of the order of electronegativities. I don't necessarily accept the exact pKa values that this site quotes for the hydrogen halides, but the order of acidity is well known. Why is this? It is a question of the H–X bond strength. Fluorine forms the strongest bond to hydrogen and iodine the weakest because fluorine is the smallest of the halogens and the orbital overlap with hydrogen is greatest. Physchim62 (talk) 00:03, 23 December 2006 (UTC)


The acidity of the hydrogen halides is also explained by the fact that the anion has higher charge density (due to the smaller size) as you go up the group making the conjugate base a bit stronger (counteracting the electronegativity effect). This is a different issue. My point is that either sulphuric acid is stronger than HCl or it is weaker. Only one of these statements can be true and the pKa values provided in wikipedia should reflect the true statement. Since on-line sources are conflicting (I've found sites having consistently pKa for HCl -7 or -8, while for sulphuric acid pKa1=-3 and others pKa1=-9 or -10) I can't say which is correct.
I don't have library access to references so I can't check physical or analytical chemistry books, but there ought to be an official, generally accepted table. I might not be able to find it but someone should be. I understand that there are discrepancies for estimating Kas in that order of magnitude but it is not acceptable to have so huge deviations (from -3 to -10) or not to be able to discriminate which acid is stronger.
Anyway any encyclopedia ought to provide the current knowledge so if there is officially an unresolved conflict it should be mentioned, instead of providing only one side as a fact. If on the other hand the issue is resolved it should make sure it provides not only the correct value but also a reliable and accessible reference, proving that this is the officially accepted value.--84.254.22.22 10:43, 23 December 2006 (UTC)

[edit] Uses

from Sulfur-iodine cycle

"Additionally, the sulfur-iodine cycle has a much lower maximum operating temperature compared to traditional electrolysis."

Isn't this wrong - can someone please check and correct. Thanks.87.102.7.133 14:43, 31 January 2007 (UTC)

removed for now:

" With an efficiency of around 50% it is more attractive than electrolysis,"

"  Additionally, the sulfur-iodine cycle has a much lower maximum operating temperature compared to traditional electrolysis."

The efficiency fact needs qualification - is this theorecical or practical?

The second statement as far as I can see is just wrong - it's the other way round.87.102.7.133 15:41, 31 January 2007 (UTC)

[edit] formula

what is the formula for sulfuric acid in acid rain??? please help!O~O —The preceding unsigned comment was added by 86.6.160.152 (talk) 16:06, 19 February 2007 (UTC).

The same as anywhere else in the universe - H2SO4! Walkerma 16:43, 19 February 2007 (UTC)
Being in water, though, it is ionised into H3O+ and sulfate ions, as described in the article. Walkerma 16:44, 19 February 2007 (UTC)

A good start would be to look in acid rain for such info. It is nicely explained there (as it is here, Martin ;-). Wim van Dorst (Talk) 22:41, 19 February 2007 (UTC).

[edit] Citations needed for world production

Tonnes produced per year should have a citation. Mrweatherbee 03:14, 20 February 2007 (UTC)

[edit] use as a weapon

Please add a paragraph describing its use as a weapon in reality (not fiction), for example http://news.bbc.co.uk/2/hi/africa/6498641.stm --Sonjaaa 07:41, 29 March 2007 (UTC)

[edit] type of bond

Is this an ionic bond, or a covalent bond? —Preceding unsigned comment added by J Iron Ferrum (talk • contribs) J Iron Ferrum 04:02, 7 April 2007 (UTC)

Covalent bonds are present in sulfuric acid, as indicated by the lines drawn in the structure drawing. If it gets put with an ionizing solvent such as water or liquid ammonia, it reacts with these compounds to produce something like H3O+ and HSO4−, which is now ionic. Note that even in HSO4−, the sulfur and oxygens are still connected with covalent bonds. Walkerma 06:35, 6 April 2007 (UTC)

I'm still confused, there looks (to me) like there are too many bonds, the maximum possible valence electrons per atom were 8, if it were covalent there would be 2 to each hydrogen (whic can only hold 2) 8 to each oxygen, but 12 valence electrons to Sulfur, also NaCl isn't written with a + or -...J Iron Ferrum 04:02, 7 April 2007 (UTC)

Sulfur, having low lying d-orbitals, can break the octet rule (as can other 3rd row atoms like phosphorus and chlorine). Regarding NaCl, it is not written with charges for simplicity, but it exists totally as Na+ Cl−, see the crystal structure on that page that shows how the ions pack. When my students write NaCl as Na-Cl, implying a covalent bond, I shout at them...it's ionic! Walkerma 05:30, 7 April 2007 (UTC)
See also hypervalent molecule. Physchim62 (talk) 09:03, 7 April 2007 (UTC)

!!!It's sulphuric, not sulfuric!!! (unsigned) Not according to the ACS, the RSC, or IUPAC. Walkerma 05:30, 7 April 2007 (UTC)

[edit] Home production of conc. sulfuric acid

Does boiling sulfuric acid drive out the water in a dilute solution, or does it merely liberate sulfur trioxide? I am curious about this: apparently on heating of dilute nitric acid, nitrogen dioxide is liberated.Crappitrash 16:10, 28 May 2007 (UTC)

Yes, concentrated sulfuric acid can be produced by evaporating dilute aqueous solutions of the acid (for example, by heating an open container of car battery electrolyte liquid). However, I seem to recall that sulfuric acid forms an azeotrope with water at 98% concentration; therefore, attempting to boil water away beyond that point would probably be futile. Also, it would be wise to select containers made of appropriate materials when attempting to concentrate the acid in this way, since fuming, boiling-hot concentrated sulfuric acid will make short work of most household vessels made of metal, such as steel or aluminum kitchen pots. Non-borosilicate glass jars are also not recommended. --Ryanaxp 19:48, 28 May 2007 (UTC)
Expanding this line of thought, it might be pertinent to list among the forms that are generally used, e.g. battery acid, how it is usually bought for these purposes. That is "5.99 Molar used as battery acid is sold in auto parts stores." Same goes for many common chemicals -- whether they are available retail or to the general public is an important bit of information (with many implications) that wikipedia tends to miss.

[edit] Minor wording & grammar cleanup.

Just cleaned up everything before the Ammonium section. Mostly fixed badly-worded, run-on, or confusing sentences. That's one of the biggest problems with WP pages written by experts in scientific subjects; they never bring the language down to a level understandable by a layman. That's unfortunate. Anyway, I attempted to bridge that divide a bit. Keep what ya want, fix what ya don't. 97.82.247.200 20:35, 4 July 2007 (UTC)

Thanks! This is an important article, and it needs a polish every now & again. Keep up the good work, Walkerma 20:46, 4 July 2007 (UTC)

[edit] "is produced in greater amounts than any other chemical besides water"

This statement is not true; production of NaCl is greater than that of H2SO4. Or it could depend on what is meant by "produced": one could argue that H2SO4 is produced by chemical reactions while sodium chloride is merely extracted. But in that case the comparison with water would be utterly irrelevant. Therefore I'm changing the phrase to "is one of the top products of the chemical industry". --Itub 12:04, 5 July 2007 (UTC)

[edit] Clear & Colorless = Not entirely accurate?

The article says H2SO4 is a "clear, colorless, odorless liquid", however many MSDS, including the NIOSH pocket reference linked to at the bottom of the article state it can range from clear to a dark-brown, oily liquid, with the pure form being a solid at 51 C. I'm not sure if if color change is related to concentration, so I'll leave it to someone more familiar with the details to make the change, but I think it should be added, if for no other reason than to keep that one person from reading the article and accidentally deciding a substance can't be H2SO4 because of its dark color. It should be noted that almost every concentrated sulfuric acid drain cleaner in the US is brown to dark brown (although some are artificially colored black, and don't count). Saying H2SO4 is clear & colorless just isn't 100% accurate. 97.82.247.200 10:16, 21 August 2007 (UTC)

This article is about the pure sulfuric acid. Small amounts of dirt get oxidized to black polimeric stuf and the sulfuric acid is brown. The sentence that comercial available sulfuric acid can range in colour from colorless to black should be mentioned.--Stone 13:50, 21 August 2007 (UTC)

So, 98% sulfuric acid that has no impurities will be completely clear -not just lower concentrations?
Out of curiosity, what procedure would a lab use remove those impurities? My first thought is filtration, but I can't think of a filtering medium that sulfuric acid wouldn't destroy (or at least affect). Would it need to be distilled to clarify it? 97.82.247.200 20:37, 21 August 2007 (UTC)

[edit] Industrial Hazards

Please remove the following statement:

Water should not be used as the extinguishing agent because of the risk of further dispersal of aerosols: carbon dioxide is preferred where possible.

Wikipedia is NOT an instruction manual.

Please see WP:NOT for more examples. Let's pay attention to policy, people. 172.136.253.232 01:00, 26 September 2007 (UTC)

[edit] more fictional uses

in pinky and the brain, brain once use sulfuric acid to melt the lock of his cage. just thaught you should add that. —Preceding unsigned comment added by 161.184.193.176 (talk) 02:12, 4 October 2007 (UTC)

[edit] Polarity and conductivity

I have left the comment "excellent solvent for many reactions", as this is not specified in Greenwood where the rest of the info. came from Axiosaurus 17:53, 28 October 2007 (UTC)

[edit] damn rhymes

I've removed them all because they appear to be a magnet for more and more. This is quite a ridiculous situation. In any case, the rhymes are just of passing interest, and are not directly relevant to the content, so there is no loss to the article. --Rifleman 82 02:48, 4 November 2007 (UTC)

I've been watching this article for almost three years, and from my experience someone will add a rhyme back in. It seems that hardly anyone knows useful information like current production figures or pKa, but half the English-speaking world has learnt a rhyme about sulfuric acid. I put the comment in about "no more than two please" but people quite often add a third one anyway! Let's cross our fingers and see what happens - I'd prefer it if there were no rhymes. (By the way, I wrote a song about sulfuric acid, maybe I should add that in....but unfortunately only chemists understand lines like, "You ask me why I'm caustic it's 'cause you're just like sulfuric acid."). Walkerma 03:07, 4 November 2007 (UTC)

[edit] Are the mnemonics necessary?

From the article - This can be remembered through mnemonics such as: "Do as you oughta, add acid to water.","If you think your life's too placid, add the water to the acid", "A.A.: Add Acid", or "Drop acid, not water", or "Acid to water, like A&W Root Beer" or "Put the king into the water, not the water into the king"

I think these should be removed due to this being an encyclopedia, not a textbook designed to teach scientific procedures.Firish (talk) 22:25, 19 March 2008 (UTC)

Not to mention that these unsourced and possibly made up mnemonics are pretty bad IMHO. I say get rid of them. --Itub (talk) 12:25, 25 March 2008 (UTC)
I agree, so I've removed them. -- Ed (Edgar181) 13:00, 25 March 2008 (UTC)

[edit] Concentrated sulfuric acid containment

How is this stuff ( > 90%) contained, if it burns through everything? Will Pyrex glass do? I searched around, but I didn't find any info about that, except some kind of coating will be used and the temperature matters. If the temperature is 10-40 Celcius, how? What about if it's around 120 Celcius? Please help! —Preceding unsigned comment added by 91.154.52.137 (talk) 16:56, 29 March 2008 (UTC)

It doesn't burn through everything. Glass is perfectly adequate; concentrated sulfuric acid for laboratory use is sold in glass bottles. --Itub (talk) 12:57, 1 April 2008 (UTC)


Thanks a lot for the info. But if it's so hot that normal glass would shatter, could it be stored in a heat-resistant (Pyrex, Durax) container (their structure differs from normal glass)?

If you are planning on working with hot concentrated sulfuric acid and don't know about the appropriate equipment, I think you will be endangering yourself for lack of training, and just looking up this one question on Wikipedia is not going to fix that. I think pyrex glass should be fine. But I hope you have also thought about things such as proper ventilation, what to do in case of spills or fires, appropriate clothes and safety equipment, etc. I suggest looking up a book on lab safety (I'm assuming we are talking "lab scale" here). --Itub (talk) 12:33, 4 April 2008 (UTC)
I would agree with Itub: if you don't know the answer to this question then you certainly don't know how to handle hot concentrated sulfuric acid. Physchim62 (talk) 14:40, 4 April 2008 (UTC)

[edit] Reaction with water

I believe the statement that, 'sulfuric acid is used in the production of many dried fruits', to be misleading, implying that fruits can be dehydrated with sulfuric acid, which as far as I am aware would yield nothing but an unpleasent mess of carbon; I believe that it is possible that the authour of that statement was intending to refer to sulfur dioxide, which is used as a preservative in some foods, including many dried fruits. I have tagged the sentence with as citation needed. Rob 301 (talk) 18:26, 12 April 2008 (UTC)

I'm dubious as well. Sulfuric acid can be used as a drying agent—you make sure that it doesn't come into direct contact with the substance you're drying, but it is excellent at removing the water from the immediate atmosphere—but it would seem to be rather expensive to be used for agricultural products. Sulfur dioxide, on the other hand, is commonly used as a preservative in dried fruit. Physchim62 (talk) 11:48, 13 April 2008 (UTC)