Talk:Brønsted–Lowry acid–base theory

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Redundant[edit]

Much of this information is already covered in detail at Acid-base reaction theories. Propose removing this page and adding one of the examples from here to the theories page.Sareen eng 06:20, 28 July 2005 (UTC)

Agreed. This page (and its relatives Lewis Acid theory etc...) should be subsections of a larger acid-base theory page, currently named Acid–base reaction. That page should probably be renamed. Acid-base pages on wikipedia in general seem to be a bit of a backwater, with talk pages years old and similar lapses in major edits to articles that would benefit from more attention. Zolot (talk) 20:28, 2 January 2013 (UTC)

Boric acid[edit]

I am trying to understand your use of the word "exemplifies" in the sentence "The case of boric acid exemplifies the usefulness of the Brønsted-Lowry concept as the acid does not in fact dissociate." I would say that boric acid is not an example of a Brønsted acid, but rather a Lewis acid, with the empty orbital on the boron reacting with OH-. One could explain that it is an exception, but as this article is on Brønsted acids and bases, I am not really certain why it is included. Could you comment? Dirac66 (talk) Retrieved from "http://en.wikipedia.org/wiki/User_talk:Petergans"Signed Petergans (talk) 07:14, 2 August 2008 (UTC)

Housecroft and Sharpe, Inorganic Chemistry, chapter 6. Quote "A Brønsted acid can act as a proton donor". Specifically, it does not require that the proton is produced by dissociation. Boric acid conforms to the general expression
acid + base \leftrightharpoons conjugate base + conjugate acid
Petergans (talk) 07:14, 2 August 2008 (UTC)

Thanks. I found your quote on p.163 (2nd edition 2005) and I think that it is ambiguous about dissociation and could be interpreted as you say. However chapter 6 does not mention boric acid, and all the examples of Brønsted acids there are of dissociation. So I looked through the specific references to boric acid in Housecroft and Sharpe and found on p.314-5 (sec. 12.7) the sentence "In aqueous solution, B(OH)3 behaves as a weak acid, but is a Lewis acid rather than Brønsted acid" [Authors' italics]. In view of this second quote from the same book, I think the phrase "proton donor" must be understood to refer to dissociation.

Upon reflexion, I suggest that it is worth pointing out that boric acid is different, but without stating that it is a Brønsted acid. Perhaps "Some acids form H+ (or H3O+) without dissociation of the acid. For example, the reaction of boric acid with water is ......, so that it is a Lewis acid and not a Brønsted acid." Dirac66 (talk) 03:12, 3 August 2008 (UTC)

Formulas in Image[edit]

The image in this article describing the self-ionization of water gives the formula of water as HO2 rather than H2O, and of the hydronium ion as HO3+ rather than H3O+. The renditions of the molecules, however, seem be accurate under the assumption that the larger red sphere represents oxygen. 165.124.142.247 (talk) 08:17, 8 April 2010 (UTC)

Yes, you are correct. Fixing an image requires modifying the original image file, so I wrote a note (in French) on the talk page of the (French) user who created it at fr:Discussion utilisateur:Cdang. Hopefully it will be fixed soon. Dirac66 (talk) 13:18, 8 April 2010 (UTC)
Done--Wickey-nl (talk) 15:26, 10 April 2010 (UTC)
Hello,
the problem lay in the way MediaWiki transforms the SVG in PNG. If your Web navigator can display SVG, you can check that the SVG looks different than the PNG and even than the way Inkscape shows it.
I already made a bug reports few years ago, but nothing changed…
cdang|write me 16:08, 10 April 2010 (UTC)
I'll assume you are correct - I can't check as my browser does not display SVG as far as I know. Since it is better to have an image which displays correctly on everyone's browser, it will be best to keep Wickey-nl's version now. Dirac66 (talk) 20:03, 10 April 2010 (UTC)
Of course, this was not the point, it was just an explaination (the formulas are OK but not well rendered). If you use IE, you have plugins for this, see SVG#SVG and Microsoft Internet Explorer.
cdang|write me 10:20, 13 April 2010 (UTC)
It seems it is displayed correct in all browsers, now: [1]. I had replaced all text elements. --Wickey-nl (talk) 11:19, 13 April 2010 (UTC)
Do you mean you changed the texts → paths?
cdang|write me 06:50, 14 April 2010 (UTC)
I removed all texts and made new ones.--Wickey-nl (talk) 14:48, 20 April 2010 (UTC)

GA Review[edit]

This review is transcluded from Talk:Brønsted–Lowry acid–base theory/GA1. The edit link for this section can be used to add comments to the review.

Reviewer: Tezero (talk · contribs) 06:44, 24 July 2014 (UTC)


Haven't thought much about this field since Honors Chemistry in my sophomore year of high school, but why not; I can give this a shot. Tezero (talk) 06:44, 24 July 2014 (UTC)

Done.
  • "the bases are the substances" - why the definite articles?
Done.
  • "This concept was able to explain the catalytic action of acids and reaction of acids and bases in aqueous solution but failed to explain why molecules not having the above ions were able to neutralize acids and bases. This theory didn't recognize metal oxides as bases and acid-base reactions occurring in gaseous phases couldn't be explained on the basis of this theory" - Since these two things are examples of the Arrhenius theory's failures, I'd set them off with a colon instead. Also, "acid-base" should have an en-dash and "didn't" should be "did not".
Done.
  • The whole article needs more in-line citations; "Example" doesn't have a single one.
Done.
  • "Water is amphoteric and can act as an acid or as a base" - I'd prefer "amphoteric, as it can act".
Done.
  • "may be partially" - I'd put "only" before "partially".
Done.
  • There are a couple of contractions in "Limitations".
Changes made.
  • "A Lewis base, defined as an electron-pair donor, can act as a Brønsted–Lowry base as the pair of electrons can be donated to a proton. This means that the Brønsted–Lowry concept is not limited to aqueous solutions" - Am I understanding this wrong, or does this make the Lewis base and the other member of the partnership share an ionic bond? If not, why not? This'd be worth noting.
Changes made.
  • This article doesn't talk at all about Bronsted and Lowry coming up with the idea outside the image thumbnail. Of particular note is that they did it independently - was there Alexander Graham Bell-style controversy involved?
Mentioned them in the main body of the article.
Skr15081997, they're in the intro but nowhere else. Surely there's a little you can elaborate on with them? At the very least, put them coming up with it independently somewhere in the main body text. Tezero (talk) 13:56, 25 July 2014 (UTC)
Tezero they are mentioned in the first para under the section "Properties of acids and bases". I could not find how they came up with their theories. If I am getting it right;you mean that they should be mentioned in a separate section.--Skr15081997 (talk) 14:08, 25 July 2014 (UTC)
@Tezero:a separate section covering them has been created.--Skr15081997 (talk) 14:59, 25 July 2014 (UTC)
Skr15081997, after a cursory perusal of Google Books, I wasn't able to find any more either. At any rate, I think this is sufficient for GA, so let's do this. Tezero (talk) 16:45, 25 July 2014 (UTC)
  • In citations 1-3 and 7, where do the page ranges end?
Done.
  • What university or other institution is "gonzaga.edu" affiliated with? This and "chemed.chem.purdue.edu" need their institutions listed in plain English as publishers, and if these places have articles, they should be linked.
Done.
  • What makes Boundless, chemteam.info, and that calendar Google site in citation 10 reliable sources?
Replaced them with reliable sources.

Ping me when you've responded to or fixed all of these. Tezero (talk) 13:34, 24 July 2014 (UTC)

@Tezero: the issues have been addressed.--Skr15081997 (talk) 07:47, 25 July 2014 (UTC)

Major revision[edit]

I have made a major revision following on from earlier edits.

  • Concentrating on the theory and its applications.
  • New section on non-aqueous solutions.
  • Replaced "Limitations" by comparisons with Lewis and Lux-Flood theories
  • Removed "Strength of acids and bases" as this is not specific to Brønsted–Lowry theory. Links are still available on the info box.
  • Cleaned up the references and removed references to Web articles.
  • Removed the "Good article" tag as so much content has changed.

Petergans (talk) 08:39, 26 August 2014 (UTC)

Boric acid is still wrong. And BF3 too.[edit]

Before nominating this article as a Good Article, I think we need to fix the major errors. By definition, a Bronsted acid is a species HA which donates H+ to a base and forms A-. As I pointed out above in 2008, the fact that B(OH)3 accepts an OH- and forms B(OH)4- makes it a Lewis acid and not a Bronsted acid. Housecroft and Sharpe (2nd ed, p.314) say explicitly that B(OH)3 behaves as a weak acid, but is a Lewis acid rather than Bronsted acid.

The article also says that BF3 is an acid in both Lewis and Brønsted-Lowry classifications and emphasizes the consistency between both theories. I believe that BF3 is an acid in the Lewis sense only, and that the two theories are not in fact consistent.

I think that mention of B(OH)3 and BF3 should both be removed from this article since they are not in fact Bronsted acids. Unless of course we accept the Russian source cited in the boric acid article which claims that boric acid forms both B(OH)4- (making it a Lewis acid) and also BO(OH)2- (making it a Bronsted acid). If we accept this, then we would have to mention both of these ions.

For now I will move boric acid into the Lewis acid section, and place a citation needed tag for BF3. Dirac66 (talk) 00:36, 27 August 2014 (UTC)

This is a moot point. If Brønsted-Lowry theory originally dealt only with proton transfer, you may be right. I have not checked with the original publications. I include boric acid because it is consistent with the general definition, acid + base is in equilibrium with conjugate acid + conjugate base and because protons are liberated when it dissolves in water. One can also look at it as the product of a reaction.
B4O72- + 2H+ + 5H2O is in equilibrium with 4B(OH)3
The borax anion clearly accepts protons, making it a B-L base. Therefore B(OH)3 must be a B-L acid. It reacts with B-L base, hydroxide, in the reverse reaction, to form borates.
Let me quote from Shriver and Atkins, Inorganic Chemistry, 3rd. edn. p143. " [Lowry and Brønsted] suggested that any substance that acts as a proton donor should be classified as an acid". Boric acid complies with this statement. From the same source, p336, "boric acid itself is in fact primarily a weak Lewis acid". My interpretation of "primarily" is that it can also be classified as a B-L acid.
On the general point, it is important that theories of acids and bases should be consistent with each other. Is is reasonable to say that Lowry-Brønsted theory fails to classify B(OH)3 as an acid? I don't think so - B and L must have known it as an acid as the old name, boracic acid, says. If one accepts B(OH)3 as both a Lewis and a B-L acid, then BF3 is also an acid in both classifications.
Please undo your changes until we have reached agreement. Petergans (talk) 09:18, 27 August 2014 (UTC)
For boric acid, my interpretation of Shriver and Atkins’ word “primarily” is that B(OH)3 primarily acts as a Lewis acid to form B(OH)4, and may also act as a Bronsted acid to form BO(OH)2. Bronsted and Lowry in 1923 did not know about B(OH)4 (detected later by Raman spectra which did not exist in 1923), so would have assumed boric acid is exclusively a Bronsted acid meaning that if forms BO(OH)2.
For multistep reactions, my understanding is that the labels Lewis acid and Bronsted acid apply to the reactants of individual steps. So BF3 cannot be a Bronsted acid as it has no H to donate. It can react with water to form a complex F3B-OH2 which donates a proton in a second step, but then the Bronsted acid is the complex F3B-OH2, not the initial BF3.
Similarly the hydrolysis of borax is clearly a multistep reaction. I don’t know the mechanism, but some of the individual steps may well involve Bronsted acidity.
As for consistency, scientific theories and definitions are not always consistent with each other. B+L explained all acid behaviour as proton donation, and I believe simply did not consider BF3 to be an acid. Lewis’ theory was more general and succeeded in explaining BF3.
Finally as to my recent changes, I have tried to minimize them. For BF3 I merely added a citation needed tag, which is always allowed on Wikipedia. Can you find a source which says explicitly that BF3 is a Bronsted acid?
For boric acid I considered a citation needed tag also, but then realized that the actual statements about boric acid are correct. The problem is the placement of these statements in the Bronsted acid section, so I just moved them down to the Lewis acid section and added a mention that the reaction with OH is Lewis acidity. Do you have a source which says explicitly that it is Bronsted acidity? As I said above, the statement of Shriver and Atkins can be interpreted as referring to another reaction. Dirac66 (talk) 20:22, 27 August 2014 (UTC)
I'm not too bothered about specifying acid types. What I was trying to get at is the consistency between the different theories. An acid is an acid by any other name "What's in a name? That which we call a rose by any other name would smell as sweet" (Romeo and Juliet) Petergans (talk) 08:58, 29 August 2014 (UTC)
The theories are not completely consistent with each other, since some reactions are acid-base according to Lewis but not to Bronsted. For example the reaction of BF3 with (CH3)2O to form a complex.
And Shakespeare also wrote "Some are born great, some achieve greatness, and some have greatness thrust upon them." (Twelfth Night). Here I would say: Some Lewis acids are born Bronsted acids, some achieve Bronsted acidity by a preliminary step (e.g. BF3 + H2O → F3B:OH2, and some should not have Bronsted acidity thrust upon them :-)) Dirac66 (talk) 19:02, 29 August 2014 (UTC)