Wikipedia:Featured article candidates/Acid dissociation constant/archive2

The following is an archived discussion of a featured article nomination. Please do not modify it. Subsequent comments should be made on the article's talk page or in Wikipedia talk:Featured article candidates. No further edits should be made to this page.

The article was not promoted by User:SandyGeorgia 21:48, 6 December 2008 [1].

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Acid dissociation constant

Nominator(s): Petergans

previous FAC (23:04, 25 October 2008)

The article has been extensively revised in the light of FAC-type comments and I believe that it now conforms to WP:MOS. There has been much discussion regarding references. The current text follows Wikipedia:Scientific citation guidelines.

The content of this article is mostly “”common knowledge”, that is, it can be found in a wide variety of text-books on physical, inorganic, organic and analytical chemistry.. Whereas no one text-book covers all the subject matter, the advantage of WP is that it is not tied a specific teaching program and can provide broader coverage. The fact that a number of text-books are cited provides the general basis for verifiability and reduces the need to support every single paragraph with a citation. The items in acid dissociation constant#further reading provide additional verifiability support. Note also that I follow the normal procedure in chemistry, of placing the reference number close to the item being referenced, whenever it would be ambiguous as to what is being referenced if that reference were placed at the end of the sentence or paragraph. Petergans (talk) 09:49, 19 November 2008 (UTC)

• Support. I supported the previous nomination already, and now the article is even better, so there's not much else I can say. --Itub (talk) 10:06, 19 November 2008 (UTC)

• Support. I spent some time after the last FAC trying to identify MOS issues with the article, and everything I could find has been fixed. I also went through the content from the point of view of a layman with a moderately technical background; everything I found that needed clarification has been improved upon or expanded. The article now meets FAC standards and I am happy to support. Mike Christie (talk) 10:53, 19 November 2008 (UTC)

• I'm not sure how to deal with the MoS requirement to avoid special characters in section headings: I left a query at Wikipedia talk:Accessibility#ACCESS check. SandyGeorgia (Talk) 18:52, 19 November 2008 (UTC)

Oppose. Although accurate and comprehensive, this technical article would be less of a chore to read if some attention was paid to the prose. Throughout the article complicated phrases are used to express relatively simple thoughts. Here are some examples:

• "For a quantitative understanding" - does this mean "to measure"?
• "...also a prerequisite.." - how about "necessary"?
• "When operating under the assumption that.." - why not "If it is assumed" or even "Assuming that.."
• "..has a limited solubility.." - "does not dissolve well"?
• ".. with the addition of.." - "by adding"?

These are just a few random examples; there many more. There are other problems such as "it has a measurable pKa range" - so what is the unmeasurable range? Here, "all protons have been removed", have they, or are they still there but no longer free? I also noticed that Pauling's rules are linked in the body but not the Lead and I fixed one typo. I feel bad by opposing this FAC because I know the amount of blood sweat and tears that goes into these candidates, but the article does need more work. Graham Colm ^Talk 13:15, 22 November 2008 (UTC)

I see what you are getting at, but I fear that we are dealing with differences between the language used in science and in general. The phrase "quantitative understanding" was chosen carefully. It actually means understanding of quantities that cannot be measured experimentally, as opposed to "qualitative understanding" which means knowing, roughly, what is going on. "Prerequite" is used because the pK_a values have to be determined before the other study can begin. "solubility" is a quantitative concept, but "dissolving well" is qualitative, and so on. I put this question to Graham Colm: Surely the use of precise language is important in a featured article, even if the language is somewhat convoluted? The "chore" is rewarded by a deeper understanding of the topic. May I also add that the language has already been given a very thorough going over by Mike Christie, as detailed above. Petergans (talk) 18:24, 22 November 2008 (UTC)

Of course precise language is needed, but I disagree with you regarding convolution. I am watching this page and I will be interested to see what other reviewers have to say. And, with regard to precision, why is there a mixture of " pK_a values" and "pK values" in the article? Graham Colm ^Talk 19:12, 22 November 2008 (UTC)

I'm reinstating my oppose because of this edit summary:[2]. Graham Colm ^Talk 22:10, 2 December 2008 (UTC)

On the specific point, the subscript may be dropped if it clear from the context that subscript "a" is implied, not the alternative "b". Petergans (talk) 23:09, 22 November 2008 (UTC)

Support and comments. An excellent article, with no obvious errors or omissions (although my chem degree is very ancient). Very clear exposition. Three quibbles

• A knowledge of twice in last sentence of lead
• Factors that determine the relative strengths of acids stray struck through sentence

That was work in progress which is now complete. Petergans (talk) 16:50, 23 November 2008 (UTC)

• Final refs not in numerical order

jimfbleak (talk) 16:18, 23 November 2008 (UTC)

Comments -

• Current ref 9 (Project: Ionic..) is lacking a last access date.

donePetergans (talk) 16:11, 25 November 2008 (UTC)

• Please spell out lesser known abbreviations in the references, such as IUPAC.

done Petergans (talk) 16:11, 25 November 2008 (UTC)

• Current ref 20, the author appears to be http://www.chem.wisc.edu/areas/reich/

How come? I used the citation gadget on my toolbar, which made no mention of author. Petergans (talk) 16:19, 25 November 2008 (UTC)

That's the "home" page for the information in this ref http://www.chem.wisc.edu/areas/reich/pkatable/. The sidebar at the bottom says "This page by Hans J. Reich" also, which would indicate authorship. Ealdgyth - Talk 17:14, 25 November 2008 (UTC)

OK, Reich is the copyright holder for the web-page, but ref. 20 gives the table title "Bordwell pKa Table (Acidity in DMSO) " as Reich has taken the data from Bordwell, who in turn extacted it from the literature. Please suggest how this reference needs to be modified. Petergans (talk) 21:43, 25 November 2008 (UTC)

• Current ref 22 (Rochester, C. H....) needs a page number/chapter/section

This is a general reference as with those in the applications section.Petergans (talk) 16:19, 25 November 2008 (UTC)

• Same for current ref 23 (Olah...), current ref 43 (Dunn...), current ref 43 (Martin...), current ref 44 (brenner...), current ref 45 (Scorpio...), current ref 46 (Beynon...), current ref 47 (Perrin...), current ref 48 (Garfin...), current ref 49 (Hulanicki...), current ref 51 (Avdeef...), current ref 53 (van Leeuwen...), current ref 55 (Stumm...), current ref 56 (Snoeyink...), current ref 57 (Millero...).

Otherwise, sources look okay, links checked out with the link checker tool. Ealdgyth - Talk 14:21, 25 November 2008 (UTC)

Refs 40 and higher numbers are in the "Applications and Significance" section. I asked Peter about specific page numbers for these in a review I did on the talk page; it seems that for many of these references much or all of the work cited covers the topic discussed. I think that means it's OK not to cite page numbers in those cases. Mike Christie (talk) 14:48, 25 November 2008 (UTC)

Heh. How big are these works? If they are 200 pages plus, it's going to be hard to satisfy WP:V if folks have to look through 200 pages. I mean, by that logic, I could just cite a biography of William the Conqueror to two footnotes and have done with it (there are two major scholarly biographies at the moment) since "much or all of the work covers the topic discussed"... Ealdgyth - Talk 14:53, 25 November 2008 (UTC)

WP:V has nothing to do with how much work someone has to do to verify the citation: if it did, we would ban all non-Internet citations and all citations in languages other than English. On the other hand, for example, there are plenty of verifiable citations that Person X is a criminal, but they should not be used for other reasons (eg, X was acquitted on appeal). Whatever happen to WP:AGF? Physchim62 (talk) 15:08, 25 November 2008 (UTC)

Calm, calm, please. I am not suggesting that you've made up anything, just that generally if the work is large, we try to cite a range of pages, or chapters, for the ease of readers following up on citations. I'm not sure why asking for a smaller range of information than a whole work is assuming bad faith. I even asked what size the works are, because if they are small works, then yes, citing the whole work makes sense. Note that WP:V says "The source should be cited clearly and precisely to enable readers to find the text that supports the article content in question. Editors should cite sources fully, providing as much publication information as possible, including page numbers when citing books." Ealdgyth - Talk 15:13, 25 November 2008 (UTC)

(edit conflict) Well, after this comment I'll let Peter reply, since he's familiar with these sources and I'm not, but here's an example of what I meant. "Assessing the hazard associated with an acid or base may require a knowledge of pKa values" is cited to "van Leeuwen, C.J.; Hermens, L. M. (1995). Risk Assessment of Chemicals: An Introduction". My understanding is that the entire book deals with assessing hazards, and that the need for a knowledge of pK_a values is not something that is mentioned only on a specific page. The reference serves not only to verify, but also as a general index to the topic. Since the applications and significance section covers topics at a high level, this seems reasonable to me. I also suspect the statements made here are so generally accepted in the field that they would not be regarded as controversial, and so do not need citations; again I'll wait for Peter to comment on that. Mike Christie (talk) 15:12, 25 November 2008 (UTC)

I've added the page numbers for the risk assessment book. It took all of 30 seconds of Google Books search. I think there may be some culture shock at work here. In my experience, giving page numbers when citing books in chemistry is largely optional in the real world, because all chemistry books worth citing have good indexes and tables of contents. Textbooks and other technical books tend to go through several editions, so the page numbers change even if the facts don't change. As a reader, it is generally more useful to rely on the indexes and forget about the page numbers. --Itub (talk) 15:31, 25 November 2008 (UTC)

Ivan (Itub ) has made all the points that I was making when there was an edit conflict. Petergans (talk) 15:35, 25 November 2008 (UTC)

I understand that in chemistry they don't do page numbers, but this isn't a chemistry book, it's wikipedia. I'm fine with using general references when the work is entirely and only on the subject of the information being sourced, but I'm pretty sure that, for example, the 300 pages of Acidity Functions isn't given over entirely and completely to the Acid Dissociation Constant. I am really not asking the editors of the article to do anything that other articles don't have to do either, or that isn't supported by policy. You're welcome to cite chapters or sections, but when the work isn't devoted completely to the information being sourced, the burden is on the editors to make sure it's verifiable. To use an example from my own writing interests, most scholarly history works have good indexes and tables of content, but this doesn't allow me to just cite a book without a page number or range on a wikipedia article. However, since we're arguing in circles here, I'm more than happy to leave this one out for other reviewers to decide for themselves, it should be something all reviewers consider. Ealdgyth - Talk 17:14, 25 November 2008 (UTC)

And the reference to acidity functions isn't a reference, it's a note as to where more information can be obtained. It is arguably redundant to the wikilink to our acidity function article, but it is truly fair to say that the entire book deals with acid dissociation constants, mainly at a level which would be inappropriate for this article. The sentence should even need a reference, it is so blatantly obvious to anyone who knows what an acidity function is: however, those who propose articles for FA must suffer the consequences, as must the articles themselves it seems. Physchim62 (talk) 18:12, 25 November 2008 (UTC)

Let's not bite Ealdgyth. I am thankful for all her thorough reference checks at FAC, and it's not really her who made up the rules. My opinion is that if it just takes a minute to find something in a book by using the index, the spirit of WP:V is fully satisfied (readers are perfectly able to verify the content of the article, and the policy template at the top of WP:V refers to "use common sense"...), even though the letter of the policy says something about including page numbers. But I don't mind including page numbers when I write; I see it as relatively innocuous compared to some of the many other hoops that need to be jumped at FAC. --Itub (talk) 20:09, 25 November 2008 (UTC)

One way to resolve this issue would be to move all the general references into Further reading, which is what they are there for. Page numbers would then not needed. To have do that would be, in my opinion, a triumph of style over content, but I'd rather do it than prolong this discussion any further. Petergans (talk) 22:17, 25 November 2008 (UTC)

• Oppose. This article, while otherwise well-written and excellently-sourced, is incredibly arcane for most readers. If this were an article about an obscure concept or "deep science" topic, it would be more understandable. That is not the case in this instance, where the article is about a ground-level chemistry topic. The Manual of Style is relevant to this concern, as it addresses both jargon and the accessibility of technical articles. If the current editors are unsure of how to achieve this goal, it may be helpful to recruit an editor or two with some experience in improving the accessibility of scientific topics. This is by no means intended to denigrate the effort expended on the article. I truly appreciate the hard work that has gone into this article, the quality of the sources and the comprehensiveness of the information provided. Vassyana (talk) 15:11, 25 November 2008 (UTC)

  I spent some time reviewing the article and trying to improve the readability. It may be ground-level chemistry in your eyes, but to me, with no chemistry background, it seems quite a technical topic, so I'm not sure what to say there. On the readability question, could you provide some examples of unnecessarily technical prose? Mike Christie (talk) 16:28, 25 November 2008 (UTC)

  Is it really more wikt:arcane than "Prince of the Cumbrians and later King of the Scots. The youngest son of Máel Coluim mac Donnchada and Margaret" or "he became a hanger-on at the court of King Henry I and experienced long exposure to Norman and Anglo-French culture"? Both of them are examples from today's featured article, the bit that's currently on the front page, not the article itself, which is full of examples of terms needing explanation for non-specialists. The acid dissociation constant is neither ground level or specialised. It is usually introduced round about the first year of university studies in chemistry, depending on the country, but is sufficiently complicated that the latest official reference from IUPAC was in 2006. I would invite the opposer to strike the opposition as excessively subjective. Physchim62 (talk) 18:44, 25 November 2008 (UTC)

  I agree that arcaneness lies in the eye of the beholder; for example, I personally find some featured articles about sports hard to understand and full of jargon. I know that "other crap exists" is not a fashionable argument in Wikipedia, but since featured articles are officially considered to be Not Crap, I will venture to try it here. --Itub (talk) 20:23, 25 November 2008 (UTC)

  David I of Scotland is hardly anywhere near as arcane and incomprehensible to a general reader as acid dissociation constant. The strength of an acid in solution is a basic chemistry topic. As you mention, adc is common in first-year chemistry studies. I'm not looking for a miracle or complete rewrite of the article. I am simply looking for some explanation and presentation that will allow a general educated reader to make sense of the topic. I am not a chemist, but I am familiar with the topic and the article was difficult to parse for me. If I already have some passing familiarity with the topic and I find the article difficult to digest, it certainly does not meet WP:MTAA. Vassyana (talk) 01:42, 26 November 2008 (UTC)

  It would really help if you could give some specific examples of sentences or paragraphs that you feel could be improved. Mike Christie (talk) 02:27, 26 November 2008 (UTC)

  The strength of an acid in solution is a basic chemistry topic, but if we covered only the basic level stuff, in a way understandable to the "general reader" we would either end up with a very short article or would have to include a large chunk of a general chemistry textbook as part of the article. The article would also be incomplete and would look more like a textbook than an encyclopedia article. In my opinion, this article already goes out of its way in trying to explain related concepts that are not the main topic of the article, all in the name of accessibility. For more details, see my post in the previous nomination.[3] If you have any specific suggestions on how it can be made more accessible, it would be very helpful. --Itub (talk) 07:04, 26 November 2008 (UTC)

  It is, unfortunately, inevitable that non-scientists will have difficulty in reading scientific articles. The level of difficulty will vary from one person to another. Even people with a scientific background may have to work hard to understand an unfamiliar topic. I think the test should be: if someone is interested in the topic can that person appreciate it, even if it requires some effort over and above the normal effort of reading. Does the article meet that test Vassyana? Let me just add that there is no jargon in the article, only well-established scientific terminology. Petergans (talk) 09:11, 26 November 2008 (UTC)

• (outdent) (edit conflict) Let me be clear in stating that I am not asking for anything to be removed from the article. On the contrary, it would be a detriment to the comprehensiveness to effectively neuter the coverage. However, as currently written and presented, anything outside of the basic definition of the topic is beyond the capacity of the general reader. I strongly disagree that the article "goes out of its way" in any fashion for the sake of accessibility. As I mention above, I know what the article is about and have some familiarity with it, but I still have some serious difficulty in parsing the article. This leads me to believe the article will be almost entirely incomprehensible for the general reader. It is exceedingly difficult to pick apart specific examples for an endemic problem, as this often leads to "patchwork" solutions that do not address the underlying issue. Some specific suggestions:

• The lede. It is dense and difficult to follow. Avoid equations in the introduction. Replace jargon with simpler language. Explain in the plainest language possible, without oversimplifying into the realm of inaccuracy, what the article is about. A couple of examples of what would leave a general reader baffled before they even get through the lede:

• "In aqueous solutions, acids that release a single proton are partially dissociated to an appreciable extent in the pH range pKa ± 2."
• "Structural effects, such as intra-molecular hydrogen bonding, can also be important. pKa can be experimentally determined by potentiometric (pH) titration, but for values of pKa less than about 2 or more than about 11 spectrophotometric or NMR measurements may be required."

• Presentation. The introduction should not be so technical and jargon-heavy that a lay reader will not bother to get through the lede. The general reader should be able to walk away with a solid understanding of what the topic is basically about and how it basically works, while chemistry savvy readers should still be able to walk away with a technical understanding. These are not mutually incompatible goals. The article could generally progress from a layman's explanation to technical details.
• Some basic examples of what needs to be made clear:

• Be clear and explicit that "hydrogen ion" means a proton.
• Be clear and explicit that dissociation, in context, simply means the donation of a proton.
• Be clear and explicit that the adc indicates how readily an acid will donate a proton.

• Some examples of clear language are already extant, but (for a general reader) they are essentially buried in the article. For example, the following is found only after the arcane lede and three mildly technical definitions:

• "The acid donates a proton to the base. The conjugate base is what is left after the acid has lost a proton and the conjugate acid is created when the base gains a proton."

The article is informative, comprehensive and interesting. In contrast, it is equally inaccessible for most readers. The topic is not so specialized or arcane that an accessibile presentation is an unduly burdensome request. Vassyana (talk) 09:41, 26 November 2008 (UTC)

• If I had the slightest suspicion that these criteria were applied consistently to featured article candidates, then I might have some motivation to address them. However, I think this is a classic case of WP:IDONTLIKEIT, of FA reviewers pushing an article to be worse in their attempts to make it jump through arbitrary hoops. Physchim62 (talk) 10:35, 26 November 2008 (UTC)

• Please assume that I am acting in good faith. A request for accessibility does not seem unreasonable or an undue burden for a relatively basic chemistry topic. The Manual of Style addresses the accessibility of technical topics. As it relates to both MoS requirements and comprehensible prose, the objection is clearly relevant to FA criteria 1a and 2. Vassyana (talk) 11:12, 26 November 2008 (UTC)

• Vassyana, I understand your concerns, but you are making the assumption that simpler language is always possible. If that were true it would have been done already. You are confusing jargon, which is a kind of slang, with scientific terminology which allows for precise expression of concepts. Let me deconstruct the sentence "In aqueous solutions, acids that release a single proton are partially dissociated to an appreciable extent in the pH range pKa ± 2" to illustrate what I mean. aqueous - in water; solution - to distinguish from solid or gas; acid - a particular kind of chemical compound; single - to distinguish from acids in general; proton - the particle that is released; partially - to distinguish from complete; dissociated - as in the topic title; appreciable - giving rise to an observable effect; pH range - a quantitative statement showing how the title subject can be applied. The lead-in is necessarily terse as it is a summary. BTW you have not answered my question, above, so I will repeat it. If someone is initially interested in the topic can that person appreciate it, even if it requires some effort over and above the normal effort of reading? Please try to give an objective answer, not just one based on your personal experience. Petergans (talk) 14:31, 26 November 2008 (UTC)

• I am asserting that some complementary simpler language is possible for entry-level topics, not that it is always possible for academic topics. I have stricken the reference to jargon, as it is inaccurate as you correctly point out. However, the absence of jargon does not preclude problems with general accessibility. There is no reason that a general audience treatment cannot accompany the more precise and exacting treatment. I did not raise an issue with the terseness of the lede. I expressed concern that it was dense and difficult to follow. To put it another way, the lede is complex and bewildering for a general reader. No, I do not believe the article would generally be appreciated by someone with an initial interest in the topic. For the most part, it will only be useful and interesting to readers with a solid grounding in chemistry and/or familiar with the specific topic. Vassyana (talk) 15:27, 26 November 2008 (UTC)

• (outdent) I can't help chipping in here. I'm sure that Vassyana is acting in good faith, but I think he is misguided. To make the article "accessible" it would have to be dumbed down to a level at which it is essentially meaningless in terms of the article title. I don't think that it's an FA criterion that the reader doesn't have to put in some effort on the more intellectually demanding areas. The Problem of Apollonius isn't an easy read either (first sentence starts In Euclidean plane geometry, Apollonius' problem is to construct circles that are tangent...) - perhaps that article should be sent to FA review? jimfbleak (talk) 14:54, 26 November 2008 (UTC)

I think I might have started this discussion. I never meant to suggest that scientific terms should not be used or imply that the article should be turned into baby food. It was the use of expressions like "when operating under the assumption that" and other wordy phrases that rattled my cage. I have withdrawn my opposition, but I wish the nominator would make some effort to address these criticisms—I cannot see any changes to the article that have been made in an attempt to reach a consensus on this. Graham Colm ^Talk 15:09, 26 November 2008 (UTC)

• (ec) I'm not asking that the article as a whole be "dumbed down". I state multiple times above that I am not looking for material to be removed. I am asking for additional material that allows a general reader to comprehend the topic. Vassyana (talk) 15:27, 26 November 2008 (UTC)

• The problem is that the MoS is inconsistent, and Vassyana is only using those parts which appeal. The article as it stands in 69k of wikitext. A relatively high proportion (compared to other FACs) of that is in tabular material, equations and references. WP:SIZE comments that "Readers may tire of reading a page much longer than about 30 to 50 KB, which roughly corresponds to 6,000 to 10,000 words of readable prose." The article is at 5000 readable words, without counting tables and equations, by a quick run through a well-known word processor. Let us accept that, with equations, technical language and tabular material, the article is 'content-dense'. So, should the authors:

1. expand the article, thereby risking FACR 4 and WP:SIZE (personally, I find it ironic that this should even be suggested, given that Vassyana apparently finds the article difficult to read already); or
2. move material to other articles, thereby risking FACR 1(b); or
3. remove material, thereby risking FACR 1(a–d), and in particular FACR 1(a) which states that the prose should be of a "professional standard"?

• I'm honestly (but only intellectually) interested in comments. Physchim62 (talk) 18:45, 26 November 2008 (UTC)

The "readable prose size" of the article is only 27Kb; I don't think there's any risk of the article becoming too long. I don't see any suggestions to trim it by moving or cutting material, so I think we're OK there. I'm not sure what Vassyana meant by "additional material", but given his earlier comments it may be that he is still looking for some rephrasing.

I copyedited the article myself, and by the time I was done I felt the article was clearly written. However, every copyeditor has blind spots, and I think it's entirely possible that another pass by a copyeditor familiar with technical writing would help. Graham's example of wordy prose ("when operating under the assumption that") could probably be improved. The point at issue doesn't seem to be whether the material is accurate or complete, just whether it could be rephrased in a way that would be more readable to a non-technical audience. Chemistry reference works are likely to elide explanations that are helpful to general readers; but conversely, few general readers will find their way to this article, and some understanding of the background facts of basic chemistry can be assumed. We're not going to explain what an atom is, for example; and I'd say that the fact that a hydrogen ion is a proton is something that doesn't need to be made explicit here. But another look at the prose with an eye to readability is a good idea. I will ask someone to take a look, but they may not have the time or inclination to help, so it would also be good if the chemists reading this could try to look at the prose with a fresh eye. There may well be places, such as the phrase Graham mentioned, where improvements can be made. Mike Christie (talk) 20:23, 26 November 2008 (UTC)

I've made some changes to the lead, to try to introduce the subject as clearly as possible to people with no background in chemistry. Tim Vickers (talk) 21:19, 26 November 2008 (UTC)

Thank you Tim!, at last we have another editor who sees the bigger picture. The Lead is much improved—the whole article needs similar attention (IMHO).Graham Colm ^Talk 21:37, 26 November 2008 (UTC)

Nothing that TimVickers reverted his edits per objections here. SandyGeorgia (Talk) 18:47, 28 November 2008 (UTC)

• Oppose for the moment. If that's an "improvement" in the eye's of FAC reviewers, then I can only implore the nominator to withdraw the candidacy. While acting in the best of faith, Tim has substituted precise and incorrect terms for precise and correct ones, so nixing the scientific value of the lead. Physchim62 (talk) 22:00, 26 November 2008 (UTC)

I'm sorry, which piece did I get wrong? Tim Vickers (talk) 22:31, 26 November 2008 (UTC)

Was that the problem? But you said "terms" so there must be something else. Tim Vickers (talk) 22:34, 26 November 2008 (UTC)

That was the worst, with serious errors on both lines edited, but this is also very confusing from the point of view of complex formation. Physchim62 (talk) 23:20, 26 November 2008 (UTC)

I've placed the science on the article talk page, as this page is already getting long. It seems that my objection to the second edit wasn't Tim's fault at all: my apologies. It's amazing how you miss things when you've read an article too many times… Physchim62 (talk) 00:35, 27 November 2008 (UTC)

I agree with Physchim62, the scientific content has been seriously degraded and some edits are unacceptable. May I make two pleas:

1. Don't edit the text unless you are thoroughly conversant with the subject matter and understand the technical terms.
2. Do your edits first in a sandbox. Its going to take me ages to work through the dozens of multiple edits from the last few days.

One of the things that concerned us when preparing the article for FAC was length. If, as now appears to be the case, length is not an issue, I can certainly expand some parts and give more explanation. Petergans (talk) 22:57, 26 November 2008 (UTC)

OK, since I seem to have accidentally introduced other errors that I didn't catch, I've reverted my changes. I'm sorry to have caused any problem. Tim Vickers (talk) 23:09, 26 November 2008 (UTC)

I can't find the exact comment now, but one previous criticism was that the older version of the article used a sort of 'semi-summary' style. Another way of improving the readability would be move some of the discussion of, for example, non-aqueous solvents to their respective articles, linked with a {{main}} tag but retaining enough information here to illustrate the importance of the specific (linked) topic. IMHO! Physchim62 (talk) 23:20, 26 November 2008 (UTC)

Final revisions

• Thank you, Tim, for withdrawing your edits. The current text has been very finely honed over a long period of time. Clarity cannot be improved by merely tinkering with it. I have therefore gone through the entire text again, trying to improve clarity. The major changes are
  • modified lead-in
  • introduced the image for the thermodynamic standard sign
  • removed the paragraph "When operating under the assumption ..." This was added by user:eaglefalconn and I have left it in up till out of respect for that editor. In its place I've added a brief description of how to make a buffer solution, in the section monoprotic acids.
  • clarified the bit about strong acids
• If any further changes might seem desirable then please be specific about them; I can't amend generalities. Petergans (talk) 11:30, 27 November 2008 (UTC)

• Comment: I would strongly suggest putting the sentence of the lead

  For an acid-base equilibrium between a generic acid (HA) and its conjugate base (A⁻), HA ⇌ A⁻ + H⁺. K_a is defined, subject to certain conditions, as

$K_{a}=\mathrm {\frac {[A^{-}][H^{+}]}{[HA]}}$

where [HA], [A⁻] and [H⁺] are equilibrium concentrations of the reactants.

in words.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 02:28, 28 November 2008 (UTC)

• Oppose: After reading part of the article, it's completely inaccessible. I'm a master's student in physics, (I started in chemistry), and I can barely make sense the lead even after multiple reads! The lead contains weird sentences, some with vague statements such as "under certain conditions" (which?), or some overly technical/precise such as "the larger the value the more the acid is dissociated, at a given concentration, into its conjugate base and the hydrogen ion." etc... Needs to be re-written so readers don't spent half an hour trying to figure out what exactly is the article talking about. More examples below

• Introduces technical concepts with little to no explanation for laypeople

Monoprotic acid/polyprotic (in the lead), what are they?

• Gibbs free energy is thrown as if we all know what it represents
• Same goes for enthalphy
• Exothermic and endothermic could probably be changed into (releases energy) and (absorbs energy) or something similar
• "Acidic behaviour can also be characterised in non-aqueous solutions." such as...?
• "Pauling's rules" wikiling that would probably be a good idea.
• Etc...

Headbomb {^ταλκ_{κοντριβς} – WP Physics} 02:44, 28 November 2008 (UTC)

• Oppose: The lead is far too technical. Describe the formula (Ratio of Products and Educts). Don't assume the reader to know what is log_10. etc... There are so many examples which have been described above. Vb (talk) 09:54, 28 November 2008 (UTC)

Reply to last two The artice conforms to Wikipedia:Featured article criteria. Nowhere in those criteria does it say that the article has to understandable by everyone. Rather, the first sentence is "A featured article exemplifies our very best work and features professional standards of writing and presentation". This is a professional presentation of the subject matter. For an elementary introduction look to a school chemistry book. Petergans (talk) 10:57, 28 November 2008 (UTC)

The criteria states it must be "well-written: its prose is engaging, even brilliant, and of a professional standard"...the comments above demonstrate a not well-written article.--Jorfer (talk) 23:01, 28 November 2008 (UTC)

What JEF said. "Professional" does not mean "understandable by only trained professionals". There are things in science that are too complicated to be really understood by layfolks because they are so arcane and abstract, just pick any subject in condensed matter physics. What the acid dissociation constant is is something that can be understood even by high school students. While there's a lot more than what high school covers that can be said about it, it never becomes so complicated that scientists that are not chemists can't get the hang of it. This is not about sacrificing scientific accuracy for a lie-to-children type of thing, it's simply about writing for a non-specialist audience.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 23:31, 28 November 2008 (UTC)

These comments apply only to the lead-in. The lead-in is a summary, not the place to introduce details. Once the reader starts on the body of the article, the language become much simpler and explanations are given. Rutherford is quoted as having said that any scientific topic should be capable of being explained to a barmaid. I agree. If I had an attentive barmaid and a day or two to do it, I could explain it to her. After that, she would probably be able to understand the lead-in, but I would probably be banned from the bar!

In reply to Jorfer, both jimfbleak and Vassyana have said (above) that the article is well-written. Mike Christie has said that it is clearly written. Petergans (talk) 10:45, 29 November 2008 (UTC)

Well, I disagree. IMO, the lead is the place to summarize things in a way people can understand them, and I do not consider articles with such a technical lead relative to the subjects inherent complexity to be Wikipedia's finest.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 17:06, 29 November 2008 (UTC)

Simply repeating your point is not getting us anywhere. Believe me, if I knew of any way to present this complex material in a simpler way it would have been done long ago. Tim Vickers made an honest attempt at broadening the appeal. While this was welcomed by some, like Graham Colm because it appeared to do the job, in fact it was completely unacceptable from the scientific point of view. What is needed is constructive criticism. So far I have only seen suggestions which amount to dumbing down and these are not professionally acceptable. Petergans (talk) 21:38, 29 November 2008 (UTC)

Oppose - As a Chemistry Education major, I feel this article is not Featured Article status. I have not gone through the entire revised article, but the parts that I have I find access and comprehensiveness issues. The ones I am about to mention are easily fixed but point to a lack of quality:

• K_b is explained as "Historically the equilibrium constant K_b for a base was defined as the association constant for protonation of the base, B, to form the conjugate acid, HB⁺." An explanation of this in simpler terms should have followed. The K_b is the inverse of the K_a. It is the opposite of the K_a, which has the formation of the conjugate base on top, as the K_b has the formation of the conjugate acid on top.
• How can you mention K_w without mentioning that at SATP its value is 1.0×10⁻¹⁴. This is the value that the entire pH scale is based off of.
• I had to change "In common parlance the acid is said to be fully dissociated." to "It is thus referred to as fully dissociated (even though it is technically not)" which was then changed to "Hydrochloric acid is said to be "fully dissociated" in aqueous solution because the amount of undissociated acid is imperceptible." The third statement is not even true. Of course the undissassociated acid is perceptible, that is why it has an estimated pK_a of -9.3 and not -infinity. Negligible would have been the appropriate word to use there.--Jorfer (talk) 04:09, 30 November 2008 (UTC)

Really? It makes more sense to state that K_b is the inverse of K_a? It may be mathematically true, but is neither informative nor always chemically intuitive. K_b is the association constant of a base with a proton. It does not require that you care about the conjugate acid. Its just an equilibrium constant like the acid dissociation constant. And for this reason, there is no article on base dissociation constant, because its a redundancy (hence the term historically).

The pH scale is not in any way dependent on the value of K_w. Nor is the definition of pH. The only thing dependent on K_w is whether we consider something acidic or basic in aqueous media, which as the current article addresses is not the only possible solvent and that pK_as will change across solvents. I will agree that not mentioning its value was an oversight, but its not as big a deal as you make it out to be.

I don't understand your quibble with how I originally phrased the point about HCl dissociation levels. The first variation of that sentence says everything that the second and third one says in fewer words. Also, that estimated pK_a does not come from experiment, it comes from estimation from determining the change in Gibbs Free Energy for the reaction. So no, imperceptible may still be correct. EagleFalconn (talk) 06:40, 30 November 2008 (UTC)

All three of Jorfer's bullet points are wrong; this is the perfect example of the dangers of oversimplification. 1) Kb is not the inverse of Ka. In water, it is Kw/Ka. It is not even the equilibrium constant for the reverse reaction, and it could only be called an "inverse" in a very loose sense. 2) There is no such thing as a pH "scale". A common misconception, usually introduced in middle or high school, is that pH can only go from 0 to 14, which look suspiciously related to Kw. But in fact, pH is not fundamentally restricted to this range, even in water. However, I agree that mentioning the value of Kw wouldn't hurt. 3) As far as I know, the association of HCl in dilute aqueous solution is in fact imperceptible (i.e., cannot be detected experimentally using current methods). The pKa can be estimated from extrapolations from other solvents, or thermodynamic or theoretical data. But as far as I know it can't be measured directly in aqueous solution. --Itub (talk) 07:48, 30 November 2008 (UTC)

Well, since the article discusses everything in terms of K_a, it is simpler to explain K_b as the opposite of K_a (acid association is the opposite of acid disassociation). For Itub, since K_w is accepted to be a constant at a given temperature and pressure, Kw/Ka = Constant x 1/K_a, thus K_b is inversely proportional to K_a, since it is the value of the opposite process.

Regardless of the actual legitimacy of the pH scale as presented in middle and high school, the pH value of 7 is considered neutral in it because of the SATP value of K_w.

My quibble about the HCl acid sentence is that it originally used the term parlance, the word vernacular easily would have improved access to the article without taking away any content as has been argued about making the article make more sense. Whatever the case, further explanation was important in improving access to the article. The problem with imperceptible was negligible gives a better idea than imperceptible even though imperceptible does not mean unable to be perceived which I originally thought before looking it up. Since the pKa is said to be taken from thermodynamics, it is perceptible (temperature can be felt so it is perceivable), so even though imperceptible can accommodate a barely perceptible phenomenon, negligible would be more exact.

The point of this is that this is just evidence of an article not ready for featured article status rather than the sole problems needing to be fixed to be featured article worthy.--Jorfer (talk) 20:23, 30 November 2008 (UTC)

But K_b is not the opposate of K_a! See my and Itub's earlier comments to this point.

pH of 7 is considered neutral for water ONLY.

Parlance - Noun, Manner or mode of speech. Vernacular - Adjective, using a language or dialect native to a region or country rather than a literary, cultured, or foreign language (both from Merriam Webster). A subtle difference, but regardless of which term you prefer it doesn't significantly change the meaning of the article enough to merit voting it down. As you mention, you previously incorrectly used the word imperceptible. You should probably look up thermodynamics since you're misuing that word too. Please stop critisizing content of articles for which you are not well versed. EagleFalconn (talk) 20:47, 30 November 2008 (UTC)

• If you don't want to call it the opposite that is fine, but it should at least be explained as the inverse. The fact is that it can be thought of as opposite because if K_a represents the forward reaction, K_b represents the reverse reaction. The inverse relationship between K_a and K_b needs to be noted.
• OK, it only applies to water, so I may be exaggerating the values importance, but water is the most common solvent. We agree that it should be mentioned though, so no more as far as that.
• Vernacular - Noun or Adjective (http://dictionary.reference.com/browse/vernacular)...In the case of the former: "the native speech or language of a place"
• Fair enough, Thermodynamics does not involve just enthalpy but entropy as well. Whatever the case, whether indirectly or directly, if a value can be estimated for it, then it must be able to be evaluated empirically which, whether directly or indirectly, will involve a perceptible process.

--Jorfer (talk) 21:47, 30 November 2008 (UTC)

Thermodynamics is a significantly broader field than just entropy and enthalpy. In fact, enthalpy is not even a fundamental concept within thermo, it is a derived one. Just because a value can be estimated does not mean it can be measured. See statistical thermodynamics and Partition function (statistical mechanics). Short story: There are events for which there are incredibly small probabilities of occuring, but by probability they must take place on some level. However, we are not capable of measuring these events and are in some cases will always be incapable of measuring them due to quantum mechanical limitations. EagleFalconn (talk) 21:58, 30 November 2008 (UTC)

• Strong Support and Strong Comments. This article is exceptionally well written, with the possible exception of the lead (see below). It leaves out no detail, and is presented in such a way that any reader with a high school understanding of chemistry and an introduction to basic equilibria would be able to follow. Regarding the lead: While the lead is somewhat opaque, I think this is a resolvable issue. See my proposed lead here. It maintains the vast majority of the details of the lead, which follows a logical structure of qualitatively defining the ADC, quantitatively defining it and then defining some of its basic aspects, followed by its broader applications.

  The proposed lead is fine apart from one point. The temperature dependence of K_a is mentioned a couple of sentences later. I have added a sentence to explain that K_a values are dependent on the ionic strength of the medium in which they are determined. I have substituted it, with that modification, into the article. Petergans (talk) 09:35, 30 November 2008 (UTC)

For those who are worried about "undefined terms" in the lead: This is not a basic chemical article. It does require an introduction to chemistry. But what you are requiring in terms of detail and introduction in the lead would require an article to be created, "Introduction to the Acid dissociation constant article." It is logically inconsistant and a slipperly slope for Petergans to not be able to assume that (and I'm pulling examples out of the FAC Nom comments) readers will not know what a logarithm is, the structure of the atom (Hydrogen ion = proton), dissociation = splitting of a chemical compound into two or more parts (all previous suggested by Vassyana), definitions of exothermic and endothermic, that non-aqueous is defined and discussed later in the article (and the lead does actually link to a later part of the article), monoprotic versus polyprotic acids....should we start including these in the lead of every chemistry article? EagleFalconn (talk) 07:15, 30 November 2008 (UTC)

Oppose Unreadable for non specialists. Especially the lead is incomprehensible to non-chemists. Commenting on the issues above a summary or lead should be the hook for the article. Is the lead is more complex for the interested non-expert reader than the body text of the article, the lead fails big time. In my opinion, simplification is sometimes acceptable for the lead; where the body text of the article has some depth that maybe too technical, these should not feature in the lead. Missing out on some sections in the body text means missing out on details, losing it in the lead will result in a reader never starting the body text at all. Arnoutf (talk) 16:37, 30 November 2008 (UTC)

After the recent revisions, the opening paragraph is much better. The whole introduction is however now very long. Some further copyediting maybe needed. I have striken my oppose since I think you are on the right track (and should not be blocked by my oppose if you continue on this track). I will not be able to attend to the discussion due to horrendous real life deadlines for the next few weeks. Arnoutf (talk) 19:01, 4 December 2008 (UTC)

Arnoutf - Out of curiosity, what is your background/familiarity with chemistry? I will grudgingly continue to conceed that the lead may need revising to be non-expert accessible, but theres only so much of a general chemistry textbook that it makes sense to include in the lead. Unless you know what types of acids there are, some basic equilibrium chemistry etc the acid dissociation constant is a worthless article to read anyway. Thats why there are wikilinks in the lead so that you can go to those articles, understand them, and then come back and understand this article.

Also, I strongly disagree about the body being "too technical." To be less technical would result in using qualitative ideas where only quantitative ones are appropriate, or handwaving concepts or artificially invoking them where this is not necessary. There is NOTHING in the lead that I consider to be overtly technical except the mathematical definition of K_a. There is terminology used, but as I said before, if you do not understand the terms used in the lead you are NOT capable of understanding the article anyway. Which, again, is why wikilinks exist. EagleFalconn (talk) 20:49, 30 November 2008 (UTC)

It's a while ago but it is pre-university high school (graduation mark A), and several material science courses during my MSc/Engineering degree. After that I went on for a PhD in science and society (ie social sciences). So no, not a chemist.

Also note that the body text is much more easily to understand than the bodytext (which is not bad, but could use some prose instead of the formulas). So sorry for any confusion there. Arnoutf (talk) 18:28, 1 December 2008 (UTC)

Comment

OK, for another example of why this article is not featured article status worthy: "The case of phosphoric acid illustrates this point. In fact salts of either H₂PO₄⁻ or HPO₄²⁻ may be crystallised from solution by adjustment of pH to either 4 or 10." This illustrates how the article both lacks comprehensiveness and quality writing (not to mention spelling...crystallized is misspelled). It lacks comprehensiveness because it begins to use the example but does not specify which pH each one is crystallized under. Someone with a scientific background like me would know that they are respective since a higher pH means a lower concentration of Hydrogen ion which means that more HPO₄²⁻ will have to be disassociated (which will crystallize at a certain concentration) to reach equilibrium. Thus the pH of 4 corresponds to H₂PO₄⁻ and 10 corresponds to HPO₄²⁻.--Jorfer (talk) 21:15, 30 November 2008 (UTC)

Both crystallized and crystallised are acceptable spellings of the word. The second is the form more common in England. It is impossible to specify exactly what pH under which each is crystallized because it would depend on what salt you had. The pH will change depending on whether you use sodium, potassium, molybdenum etc etc. Someone with a scientific background, (maybe) like you, should probably have figured out thats why it wasn't explicitly stated. Furthermore, someone with a background in English, like me, would read that sentence and notice that what it is saying is that you can crystallize those anions at a pH of either 4 or 10. Ergo, what you are critisizing is already addressed in the article. EagleFalconn (talk) 21:52, 30 November 2008 (UTC)

So the question is why are we even mentioning two specific pHs? Also, let's be civil, there is no reason to be condescending.--Jorfer (talk) 22:33, 30 November 2008 (UTC)

The two pH's are mentioned because they provide a reasonable range at which most common salts of those anions would be expected. See the relative abundance chart next to the comment. EagleFalconn (talk) 23:16, 30 November 2008 (UTC)

OK, so why don't we state that: the salt of H₂PO₄⁻ is more likely to occur at a pH of 4 and a salt of HPO₄²⁻ is more likely to occur at a pH of 10. Why are we trying to be cryptic? I understand how the math works behind this, but the person that would need to read this page most likely doesn't. The picture is meaningful only for someone who understands the math behind it. Let us show that 10^-2.15 over 10^-4 gives the ratio of Phosphoric Acid's conjugate base (and successive conjugate bases) to Phosphoric Acid at a pH of 4. The only way to make this article more understandable to a broader audience is to explain, explain, explain.--Jorfer (talk) 04:13, 2 December 2008 (UTC)

• Comment I think reading may be aided by providing a definition for certain words and phrases which are not wikilinked in their first instance. For example:

• • "equilibrium constant" in the Definition section is never defined and is not wikilinked, defining it would make the article a bit more accessible.
  • "Aqueous solution" is also never defined, providing a simple definition in the first instance of this phrase would be a big help.

Wrad (talk) 22:54, 30 November 2008 (UTC)

Have wikilinked equilibrium constant in definitions, though it was wikilinked in the lead (point is still well taken). Defined aqueous in both the lead. EagleFalconn (talk) 23:19, 30 November 2008 (UTC)

• Comment - I don't know any chemistry and I couldn't understand a bit of the first two sentences. - Peregrine Fisher (talk) (contribs) 01:41, 1 December 2008 (UTC)

Comments from Dweller

I saw the comments about the FAC at WT:FAC. I think I'm well placed to comment, as a scientific ignoramus, who often nominates at FAC articles about cricket, a subject entirely alien to most (ie American) Wikipedians, bringing bagsful of problems regarding jargon and "impenetrability".

I'll say what I see.

More anon. --Dweller (talk) 11:27, 1 December 2008 (UTC)

• Is there a reason why the elements of the equation are defined in a different order to which they would naturally be read? (Ie left hand side, then top line, left to right, followed by the bottom line)

Added sentence "Like all equilibrium constants, it is the ratio of the product of the concentration of the products to the product of the concentration of the reactants." Does this clarify why the mathematical definition is as it is? EagleFalconn (talk) 15:12, 1 December 2008 (UTC)

• A wikilink to acid might be a good idea, preferably in the very first sentence. Wording might need adjusting for this.

Done. EagleFalconn (talk) 15:12, 1 December 2008 (UTC)

• Not your fault, but equilibrium constant seems a pretty poor article. It could at least do with an intelligible definition at the top of the Lead. If one of your editors could fix this, that'd be useful, as people like me will depend on it as a fairly important explanatory link, that currently doesn't explain. Just a suggestion.

This is on mine and (I believe) Petergans' hitlist after this article. EagleFalconn (talk) 15:12, 1 December 2008 (UTC)

• Very confusing that "conjugate base" links to conjugate acid. Given that you're saying, as I understand it, that this article is about a relationship between an acid and a base, the wikilinks here imply it's between an acid and, erm, an acid.

Short answer is that the conjugate base of an acid is the acid minus 1 hydrogen ion. Conjugate acid would be a base plus one proton. They're related concepts, which the current article on conjugate acids doesn't explain. When I/Petergans decide to take on equilibrium constant, this article will need a brush up as well. EagleFalconn (talk) 15:12, 1 December 2008 (UTC)

• On my first look at the article, my eye glided right over the "Ka" in the first line, as it is ensconced in the middle of a bunch of words, which, even better, are bolded. That little bunch of italicised meaningless letters went right over my head, or, more to the point, they didn't go into my head anyway... and I was a bit flummoxed when hit with the term a sentence later. I suggest you delete it from the opening line, and introduce the concept of the term having an expression of this sort when you introduce the equation, ie, "The usual definition of an Acid dissociation constant (rendered Ka in equations) is..."

I've removed K_a from the first sentence and included the explanation right before the math part. EagleFalconn (talk) 15:12, 1 December 2008 (UTC)

• Actually, on reflection, I don't believe that the equation should be in the Lead at all.

This one I can't bend on. The equation needs to be in the lead because the ADC is a quantitative concept, and any lead that is going to purport to summarize the topic is going to need the equation. EagleFalconn (talk) 15:12, 1 December 2008 (UTC)

Can't the Lead at least say straight away that the strength of an acid is indicated by the magnitude of the ADC; that is the larger the ADC the stronger the acid? And, that for strong acids knowledge of it is of little value, but for weak acids, i.e. those found in biological systems, it is important? This would provide the lay reader with some understanding. Graham Colm ^Talk 18:59, 1 December 2008 (UTC)

Definitely not. The term "strong acid" has three distint meanings - an acid which is completely dissociated in solution, a solution containing an acid at high concentration and an acid which is very corrosive. The amendments (next post) try to address this but it is not very satisfactory. Better not to talk about the strength of an acid. Graham has accused me of behaviour " bordering on arrogance". No, sir, you seriously underestimate the difficulty of providing simpler explanations without degrading or dumbing down the content. This example illustrates just how treacherous the use of plain English can be in a context like this one. Petergans (talk) 09:48, 2 December 2008 (UTC)

I've tried to incorporate your suggestions into the lead without breaking the flow of the prose. Let me know what you think. EagleFalconn (talk) 00:50, 2 December 2008 (UTC)

--Dweller (talk) 11:49, 1 December 2008 (UTC)

• General comment I have to say, I'm really caught by this article. I find it almost 100% unintelligible, even by following the wikilinks. This is partly not the fault of the editors, as the wikilinks lead to many very poor articles themselves. However, and this is a crucial point, if I was reading one of those other articles, I would not be able to come here and understand what this topic was talking about. How can I approve that an article espouses our highest standards of writing, if I can't understand it? Wikipedia is supposed to be an encyclopedia, not a text book. Encyclopedias are supposed to be good at making their topics comprehensible, at least in terms of framing the topic, for any reader prepared to dig a little and cross-reference the technical terms. I am prepared to that, but still can make no headway. I have come across another FA that is a good parallel - 0.999... includes material maybe 75% of which I didn't understand, but it succeeded in explaining what the issue was and why it was important in an accessible manner, before then delving into the technicalities. However, and it's a big however, this clearly meets the WIAFA criterion for "professional" writing (boy, does it meet that), so I feel it's difficult to oppose. The best I could do was to drop a line to User:Raul654 and request his input. And in the meantime, I'll scratch my head a little more and see if I can get myself off the fence. --Dweller (talk) 15:28, 1 December 2008 (UTC)

Comment on Dweller. Be careful not to confuse professional writing as in "writing for a professional audience" with professional writing, as in "writing at the level of a professional author/writer". As far as I understand Wikipedia asks for the latter. Arnoutf (talk) 18:32, 1 December 2008 (UTC)

And by what right can FAC reviewers judge that an article is "writing at the level of a professional author/writer" in general, let alone in any particular field? What about writers who are usually paid for their work and who write for WP for free: there are at least two who have contributed to this article. Physchim62 (talk) 20:25, 1 December 2008 (UTC)

I think the other issue (professional audience) is much harder to judge. If the style, ease of uderstanding and argument, flow of prose and structure of the article is good it is professionally written. That is judgable for FAC reviewers. If you want to judge whether it is for a professional audience my guess would be that "I don't understand it, so it must be for a professional audience" is the only cue reviewers have on topics where they are no experts on. Arnoutf (talk) 22:04, 5 December 2008 (UTC)

Oppose. This is a good article, and I imagine that some college students taking basic chemistry will learn from it. However, in my opinion, it is not up to FA level yet. Since I'm aware that no two experts will agree on how to present basic topics such as this one, the authors should not feel obliged to follow my suggestions for the article. On the other hand, I must speak as I find, and I do not find this article representative of Wikipedia's best work.

• Objections per criterion 1a: I find that the level is unnecessarily high, particularly in the lead. This article is not BRST quantization or some other necessarily difficult topic. Rather, it describes the equilibrium between the gain and loss of a proton in a molecule, which is perhaps the simplest chemical reaction and a topic covered in 7th-grade chemistry classes (at least it was in mine). In my assessment, the lead does a poor job of conveying the essence of the ideas, unless the reader is already familiar with them. A motivated novice reader might be able to understand the lead by following the wikilinks, but only if the leads of those articles are better written than this one. To me, the thermodynamic explanations are particularly poorly written and poorly placed within the article; I would be sincerely surprised if non-scientists would be able to learn from them. I believe the article would be improved significantly for most readers if the authors made more effort to rationalize the concept of pKa, its dependence on chemical groups and its variations with environmental conditions.

Although I appreciate that the article cannot and should not recapitulate chemistry textbooks, and that the material should not be dumbed down or made incorrect, I suggest that the authors be more accommodating and give focused help to non-scientists reading the article. My advice would be to describe the protonation and deprotonation reactions separately, and the qualitative factors favoring each. You might explain that equilibrium is reached when their rates balance, a fact obvious to us, but not necessarily to others, even chemistry students. My teaching experience suggests that discussing the forward and backward reaction kinetics can also help students to gain an intuitive understanding of activity. I appreciate the authors' careful use of “conjugate base/conjugate acid”, which confuses many students. However, because of that confusion, I've found it better to focus on protonation states rather than trying to explain what is the conjugate base of hexalysine.

• Objections per criterion 1b: The article is not comprehensive on some points. (1) I was surprised to see no mention of computational methods to predict pKa values. (2) I think a discussion of the analogous dissociation of deuterium would help some readers to understand the factors involved. (3) Another good topic for chemistry would be other reactions coupled to deprotonation, such as H-D or thiol-disulfide exchange. (4) I found the experimental determination section deficient, particularly in its use of the word “spectrophotometry” to cover all forms of optical spectroscopy including fluorescence and its implication that spectroscopic methods including NMR are reserved for extreme situations below pH 2 or above pH 11. Other methods have been used historically, such as volumetric and calorimetric methods, as I'm sure the authors know. (5) More history of the concept would be good. (6) I appreciate the need for summary style to keep Featured Articles short, but the applications section seems rushed and random. (7) At the risk of adding yet another random example, chelation changes due to titrations might fit there nicely, with picturesque applications ranging from soils and plants (why do blueberries grow in acidic soil?) to modern biochemistry (elution of His tags from Ni columns, metal-ion binding in proteins and nucleic acids).

After our discussion on the Talk page, I appreciate the recent additions to the Hammett equation, but I think more discussion of the physical/chemical factors affecting pKa's would help the article become (a) more comprehensive and (b) more accessible to non-scientists. A good qualitative discussion might go a long way towards bridging the gap with non-scientists. The variation of pKa's in a well-chosen homologous series of molecules, or the same functional group placed in different environments, could help to illustrate such factors. Aside from the well-known example of maleic and fumaric acid, there is little discussion of the interaction between pKa and molecular conformation, and interactions between titratable groups, that is, pKa shifts arising from the protonation states of nearby groups. For protein scientists, canonical examples would include Linderstroem-Lang's 1928 application of Debye-Hueckel theory and titrations of poly-lysine peptides, but those might be parochial.

On other points, I find the article overly comprehensive. (1) I'm not sure that the present tables of pKa values add much to the article that couldn't be incorporated into the text. I'm unclear why the authors chose to focus the tables on molecules, especially when the chosen molecules have redundant functional groups. The absence of molecular structures makes it hard for non-chemists to get anything out of such tables, although I understand that row spacing was a consideration. Have the authors considered instead a table of characteristic pKas of common functional groups bound to a common root, say, a methyl group? Such a table might tie in nicely to the discussion of homologous series and factors affecting pKa's. (2) The discussion of monoprotic versus polyprotic acids seems overly long, using space and reader focus that might be employed better in another way.

• Objections per criterion 3. The images do not seem up to FA level. (1) The lead image could be improved by highlighting the proton being transferred in a different color. Readers might not know what to look at in the present lead image. Even better would be an animation showing the (de)protonation reaction. (2) Several of the images seem redundant, such as the percentage formation plots for citrate and phosphate. (3) The images are not always well-integrated into the text, and their captions, while admirably brief, don't always make a clear point in themselves. Again, the authors should remember that they're writing for people who don't know the subject, rather than for those who do. Riddles are obvious only after you know the answer. (4) The x-y plots seem to be of below-average quality; can they be improved? (5) As an aside, why is ionic strength given in one figure with units of mol dm-3 instead of the more usual Molar?

I hope that the authors don't feel beleaguered by the criticism here and above. The authors can take pride in their work, but I hope they also see that the article can be improved, particularly to make it more helpful for novices. Since I'll be teaching this subject again next semester to undergraduates, I'm interested in helping to improve the article, not just to criticize it. Proteins (talk) 20:10, 1 December 2008 (UTC)

Question: Has anyone yet considered the viability of writing an "Introduction to.. article? Ling.Nut ^{(talk—WP:3IAR)} 10:11, 2 December 2008 (UTC)

• Support meets the FAC requirements. Improvements can be thought of for the lead and especially increase links to related topics such as acid, ionization, chemical bond and Acid–base reaction. This single article cannot be expected to encompass all related aspects. Retract, on rereading the comments of others, I see that the prose can be much simpler and direct. Shyamal (talk) 10:54, 2 December 2008 (UTC)

• Comment. I supported above, and my support still stands, for the reasons I gave there. However, the length of this FAC, and the nature of some of the comments, lead me to make three suggestions to the nominator and the other editors who have worked on this article.
  1. Withdraw the FAC. Resubmit it later if you are interested in doing so. The comments from Proteins are detailed and knowledgeable, and appear to have led to some modifications to the article. I would suggest that if Proteins is willing, he/she would be a valuable asset to the article as an editor and/or reviewer prior to any future FACs.
  2. Find an uninvolved editor to work on the lead. The editor should be a very good writer, either unafraid of scientific complexity or already versed in this topic, and able to appreciate the need for precision as well as the value of clear prose. If you can find someone who meets these criteria, and who is willing to work with you on a detailed review of just what the lead needs to say and how to say it, either the lead would become clearer or the editor would be able to explain to a future FAC just why the lead needs to stay as it is. Either outcome would be helpful to the reviewers here.
  3. The comment to GrahamColm about scientific illiteracy was rude and uncalled for. Even if Graham were in fact ignorant about science, this would be an uncivil remark about someone who has devoted time to trying to help the article achieve featured status. There are many who have contributed here who would like to see Wikipedia break new ground (as Petergans commented at WT:FAC) by featuring a physical chemistry article for the first time. Insulting their scientific knowledge is not only rude, but is likely to discourage those who could help the article from any further involvement. I'd like to see Physchim62 acknowledge that the tone of his edit summary was uncalled for, and I'd like to see the next FAC (and I hope there is another one) free of that kind of comment.

  I also want to add a comment about the difference between precision and accuracy. Some of the concerns expressed about proposed changes to the lead appear to be based on the inaccuracy or imprecision of the resulting statements. It's important the lead be accurate; it is not so important that it be precise. The lead can make general statements about the relationship between pK_a and the strength of acids, for example, which may not be precisely expressed, so long as the statement is qualified in such a way that the reader understands they are not reading a precise description. The qualification renders the description accurate by pointing out that it is imprecise. Some modification of the language along those lines might be worth considering.

-- Mike Christie (talk) 01:52, 3 December 2008 (UTC)

My own view as how to improve the article would be to work on Brønsted–Lowry acid-base theory and equilibrium constant, the two principles which underlie the chemistry discussed in this article. If we can get clear and accurate descriptions of those two complicated concepts, acid dissociation constant would be much easier to write.

I won't withdraw my comment about "scientific illiteracy", much as it might pain many people (not least the editor concerned). There is no point in sending scientific articles to WP:FAC if the result is a deterioration in quality, yet that is the result I have seen on many, many occasions. If my memory serves me right, I have never proposed an article at FAC; although I have collaborated on the reviews of articles proposed by others, as here. I would certainly never recommend an editor to send an article to FAC, and even less a scientific article such as this. The problem lies with FAC system, not with the editors of these articles: a small number of self-selected individuals set themselves up as the judge-and-jury of writing over a huge range of subject areas, applying their own idiosyncratic interpretations (there are as many interpretations as editors) of Wikipedia guidelines as if they were law. No individual editor can change the current sclerotic system, but that doesn't mean that editors should stand by while Wikipedia's best articles are degraded, even if it is with the best of intentions. Physchim62 (talk) 02:42, 3 December 2008 (UTC)

I might agree with you if it was just people not familiar with the subject matter that were keeping this article from becoming a Featured Article, but you have users that are familiar with the subject matter like Proteins who are objecting to it becoming a Featured Article; that should tell you something.--Jorfer (talk) 03:05, 3 December 2008 (UTC)

You may have misunderstood me somewhere. I couldn't care less if the article makes it to FA or not, as the star has become so devalued (not only in scientific articles, I might add) as to be worthless. What I do care about are the quality and accuracy of the article, as it describes a subject which is widely taught in schools and universities, and not only to chemists. Several editors have made helpful comments; several editors have made unhelpful edits: the two groups overlap, such is life on a collaborative project. Let me just quote the first paragraph from the version of Group (mathematics) that was featured:

In mathematics, a group is a set of elements together with an operation that combines any two of its elements to form a third element. To qualify as a group, the set and operation must satisfy a few conditions called group axioms, namely associativity, identity and inverse elements. While these are familiar from many mathematical structures, such as number systems—for example, the integers endowed with the addition operation form a group—the formulation of the axioms is detached from the concrete nature of the group and its operation. This allows one to handle entities of very different mathematical origins in a flexible way, while retaining essential structural aspects of many objects in abstract algebra and beyond. The ubiquity of groups in numerous areas—both within and outside mathematics—makes them a central organizing principle of contemporary mathematics.

And reviewers criticize the lead of acid dissociation constant for being arcane! As a chemist, I know more than the average person-on-the-street about group theory – I've even taught it at university level, if only to other chemists – but I still find that paragraph (and the rest of the article, for that matter) hard going. The article appeared on the main page on 5 November, it is not an old case. Physchim62 (talk) 03:50, 3 December 2008 (UTC)

Well I for one, find that piece of writing to be much clearer and much more concise than what was (still is?) on the lead of this article. The only thing I would change about this is the word "ubiquity" which has to be looked up for most people. So instead of jumping the gun and depicting nearly everyone here, including professional scientists and graduate students, many with a background in chemistry, as unproductive and unhelpful, and to insult our efforts and feedback to make your article better, you should instead try to listen to what we are saying. I passed List of baryons as a featured list a few months ago, and don't be telling me that particles physics is a simpler subject than something that is covered in 1rst year chemistry. Sure it took efforts, namely a peer review, the first try failed, but after addressing the valid concerns, of people, it passed.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 05:34, 3 December 2008 (UTC)

Re-written lead

It is clear to me from the discussions here that nothing short of a radical re-write of the lead would be needed to accomodate the reservations of many contributors. I have now done this in a way that I hope will meet with consensus. Would all those who now feel able to support the promotion of this article please indicate. I suggest you put "now support" or "still oppose" next to their name below. I also invite Proteins to withdraw his opposition on the basis that the article is already of FA standard, and ask him to collaborate on making the further improvements which he outlines. Petergans (talk) 14:11, 3 December 2008 (UTC)

Graham Colm (Talk) It looks like I have been invited to comment. I think this FAC should be archived and the lessons learnt be used to further improve the article. Re-submission a later date would allow us all to appraise the article with refreshed eyes. Graham Colm ^Talk 22:51, 4 December 2008 (UTC)

Headbomb (talk)

Comment, I think it would be simpler to simply closed this and not promote it, and re-submit it immediately after closure. This is a huge archive (86KB so far), and it would be wise to plan ahead for another very long discussion. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 09:57, 4 December 2008 (UTC)

Vb (talk)

Proteins (talk)

Comments (1) I would be willing and happy to work on this article, or an "Introduction to..." article, if that were preferable. You can count on my help. (2) If I understand how FAC works, it won't matter whether I change my !vote to support, if the objections listed above have not been addressed. (3) I'm happy to see the improved discussion of spectroscopic measurement of pKa values, but most of my other concerns have not been met. (4) I appreciate the nominator's truly valiant effort to re-write the lead, but to me it seems worse than the original for comprehensibility. :( The shorter Itub version is significantly better than both, but in my opinion, it and the whole article are incomplete and not yet at that polished level that I associate with FAs. I'm sorry, truly. (5) I'm leaving in a week for a workshop, and I'm quite busy otherwise, but I'll try to contribute some pieces of an improved article before I leave. (6) The authors might re-read Pauling's treatment of acid dissociation constants in The Nature of the Chemical Bond to see what I mean about teaching from homologous series and explaining the physical/chemical factors at work in pKa's. Such homologous series might be well-represented on Wikipedia with a <gallery> at the start of a subsection, one for each major factor determining pKa's. The gallery images would be the molecules of the series, their captions the individual pKa's, and the surtitle would describe the effect causing the change in pKa. Such galleries might make the article more comprehensible and picturesque and also allow you to do away with some of those tables. A kindly meant suggestion, Proteins (talk) 02:11, 5 December 2008 (UTC)

I have added the chloracetic acids and reference to Pauling. The remaining part of Pauling's section 7-3 is largely outdated by advances in quantum mechanical calculations and by the Hammett equation.

Proteins makes some very creative suggestions, but he should not use the FAC discussion to make them. I, for one, don't know how to make an animation, and I am just not qualified to write about proteins. These are examples of things that Proteins should do himself by editing the article. He has indicated that he is prepared to do them, so he should go ahead with them and withdraw his opposition to FAC.

One further point. Proteins has made reference to his use of WP as a teaching resource. Fair enough, but WP is an encyclopedia, and not a text-book. Text-books can give much more pedantic detail. Petergans (talk) 10:50, 5 December 2008 (UTC)

For everyone's benefit, I believe we should focus on improving the article, and not on a small bronze star. The decision to promote lies with the FAC director and his delegate, and only they can determine whether the various unaddressed objections have merit. (1') I repeat that I'm willing to help in resolving my concerns and those of others, but given my schedule, that won't happen on the typical FAC timescale. (2') I didn't mean that you should copy Pauling directly, but rather consider using his method of illustrating physical/chemical factors determining pKa values with judiciously chosen homologous series. That approach will help, I believe, when you discuss the thermodynamics and computational methods for predicting pKa. Pauling's lucid prose is worth emulating as well. (3') I don't insist on animations, although I'm sure that you would find them easy to learn. Briefly, you create the individual frames using your favorite molecular visualization program and combine them into GIF or OGG Theora format using the GIMP or some other convenient software. Once you've made one, you could probably make a dozen in an afternoon. My main point, however, was that you should spend more time improving your images, both for their instructive value and as images. (4') I don't intend that this article be a textbook presentation; I just find it unnecessarily obscure and incomplete. (5') Please don't feel as though you're beset and all alone. Others will help you to improve the article; it's a wiki, after all. I'll volunteer to make a few candidate animations and galleries of homologous series, which we can review together to see if the article might be improved by them. Hopefully, that will warm the atmosphere. Proteins (talk) 12:36, 5 December 2008 (UTC)

Dweller (talk)

Arnoutf (talk) (copied from above by PG)

After the recent revisions, the opening paragraph is much better. The whole introduction is however now very long. Some further copyediting maybe needed. I have striken my oppose since I think you are on the right track (and should not be blocked by my oppose if you continue on this track). I will not be able to attend to the discussion due to horrendous real life deadlines for the next few weeks. Arnoutf (talk) 19:01, 4 December 2008 (UTC)

Jorfer (talk) Still Opposed - Though I feel with User:Itub/ADC lead the intro will be of Featured Article status, my comments on the body have not been addressed. The body does not need to sacrifice precision to become better; it just needs to include further explanations and clearer use of language, which I have highlighted in my comments here. By the way, I congratulate Petergans and Itub on overhauling the lead. This shows the good that comes from the Featured Article process.--Jorfer (talk) 21:51, 5 December 2008 (UTC)

Tim Vickers (talk)

Vassyana (talk) Still opposed. Itub's verion of the lede is somewhat clearer, but I still do not see how it would be accessible to someone unfamiliar with the subject. As pointed out by numerous reviewers, this is a subject covered in secondary school and first year university chemistry. The lede should at least be comprehensible to the average first-year university student. I truly cannot understand why the suggestion to use an introductory-level presentation and then moving to more precise & technical matters is so controversial for an intro-level chemistry topic. Vassyana (talk) 12:34, 4 December 2008 (UTC)

What exactly is not comprehensible about my proposed lead? I'm looking forward to making it more readable. However, I'm a bit puzzled about what sort of "average first-year university student" you have in mind. Despite being taught in first-year chemistry, this topic is not as "basic" as people here seem to imply. I'm looking right now at the table of contents of the Complete Idiot's Guide to Chemistry. The relevant chapter, "Acid-base equilibria", is chapter 23. This is one of the last chapters (the book has 28), after the student has been introduced to solutions, chemical kinetics, chemical equilibria, intermolecular forces, and chemical bonding. Would you expect someone who doesn't know chemistry and jumps straight into chapter 23 to understand any of it? What can we assume that the reader knows before reading the lead? --Itub (talk) 13:03, 4 December 2008 (UTC)

If someone is not already familiar with the topic, it won't make much sense to them without serious study. I don't understand your question about the generic target, as it is fairly self-explanatory... the average freshman. It is a topic that is regularly explained to secondary and incoming university students. Actually, chapter 23 is "Acids and Bases" as a whole. Chapter 27 is "Cranking Up the Heat: Basic Thermodynamics". Based on your argument, basic thermodynamics would not be a basic concept, which is simply ludicrous. Regardless, I'm not asking for the article to sacrifice the detailed content or to even include lies-to-children type oversimplification. All that I am asking is that a non-specialist with no more than a cursory education in chemistry can walk away with a reasonable understanding of the basic points of the topic. This can be handled through addition, as the readable prose size is well under the limit. As it is currently written, the article is obscure (at best) to anyone without a prior understanding of the topic it covers. Vassyana (talk) 14:15, 4 December 2008 (UTC)

Do you mean an average freshman who already took several months of general chemistry and is now studying the chapter about acids and bases, or the average freshman who is majoring in Elbonian studies and does not know what a logarithm is?

Sorry for the misquote, and yes, this book is unusual in putting thermodynamics at the end. Many other books puts it before acid-base equilibria. Obviously, not every chapter depends on every preceding chapter; for example, acids and bases don't require a lot of knowledge about gases. But they do require knowledge about the other topics I mentioned.

Anyway, do you have any specific suggestions for making the lead more readable? Any technical terms needing explanation or linking, or anything that should be removed from the lead and deferred to the body of the article? --Itub (talk) 14:28, 4 December 2008 (UTC)

If you have access to the Idiot's Guide, the way its goes about presenting the formula and dissociation is a great template. It does not unduly sacrifice technical detail or accuracy, nor does it indulge in large explanatory tangents, while presenting it in a digestible fashion. Some of the way it avoids disruptive side explanations is by making certain elements clear by context. An average educated reader can walk away with the full basic gist of the topic. Breaking it down into direct suggestions: 1) Explain concepts that can be explained very briefly. An extra phrase here and there isn't going to hurt the quality if well-written, but will go a long way towards making the article more accessible. 2) Try to organize the information into more a building block format, as commonly done in science education (A and B, therefore C). Overly simple example: a) These are acids, in the definition most relevant to this topic. b) This is dissociation. c) This is equilibrium as it relates to this concept (no need to rehash equilibrium as a whole). d) a+b+c = acid dissociation constant. 3) Try to organize the information and rewrite it somewhat so that the context and interaction of facts is clearer to a reader. For example, the Idiot's Guide does a great job of making "HA"'s meaning clear to a reader mainly through context and discussion of the main topic. Does that all make sense? Vassyana (talk) 14:54, 4 December 2008 (UTC)

I'll look at 1 and 3, but 2, as I understand it, is something we can't do because Wikipedia, unlike the Idiot's Guide, is not a textbook. We (according to conventional Wikipedia lead style) have to cut to the chase and give a definition upfront, preferably in the very first sentence, without "building up to it". It should be closer to the inverted pyramid style IMHO (my current version of the lead does define what it means by equilibrium and some other things, although it does it after giving at least a qualitative definition of the acid dissociation constant). We don't start the lead of Death of Hitler with a mini-review of World War II or of Hitler's life, or Death Star with "a long time ago, in a galaxy far far away...." If someone comes to these articles without knowing who Hitler was or what Star Wars is, they are looking at the wrong article. Same goes for someone who comes to acid dissociation constant without knowing what an acid is. Like you correctly pointed out, the title of the textbook chapter is "Acids and bases". That is a wider scope that what my Freudian slip implied (acid-base equilibria) and much, much wider than "acid dissociation constant". I don't have access to the book, but I'm sure it does not begin the chapter with the concept of acid dissociation constant, because of the scope of the chapter, and because it is a teaching aid, not a reference. --Itub (talk) 06:52, 5 December 2008 (UTC)

The avoidance of 2) makes sense as you present it. Again, I will say that your version of the lead is significantly clearer. 1) and 3) would likely be sufficient enough to address my concerns. Regardless of how it is done, I will be satisfied (and happy to support the FAC) as long as the result allows a non-specialist with only a cursory education in chemistry to walk away with a reasonable understanding of the basic points of the topic. Vassyana (talk) 13:56, 5 December 2008 (UTC)

Wrad (talk)

Peregrine Fisher (talk)

Shyamal (talk) Some careful copyediting by a fresh eye is needed in this and the primary authors should take unacceptable copyedits as indicators of problems in the text. It would be good if knowledgeable copyeditors and the primary authors can run some positive iterations of reading and re-writing. Shyamal (talk) 10:47, 4 December 2008 (UTC)

• when their concentrations do not change in with the passing of time. -> "change with"
• Strictly speaking it should be a quotient of activities, but when Ka values are determined in a medium of high ionic strength concentrations can be used in place of activities. -> pedantic tone in use of "speaking"
• but when Ka values are determined in a medium of high ionic strength concentrations can be used in place of activities -> comma needed ?
• An acid which releases one proton, -> an acid molecule ?
• in the approximate range -2 to 12 in water -> that seems like a wide range to be termed approximate - can be trimmed
• measuring the concentration of the hydrogen ion -> measuring the concentration of hydrogen ions ?
• A polyprotic acid is an acid, such as phosphoric acid or citric acid, which can release more than one proton. - one proton per molecule ?
• Current practice is to determine the pKa value of the acid conjugate to the base. - of the base  ?
• Factors that determine the magnitude of pKa values include Pauling's rules for acidity constants - gives an impression that nature follows published rules

Ling.Nut (talk)

• Conditional Support. As part of an evolving position on articles by the folks in white coats, I'm moving toward accepting the idea that such articles need not be written for the "general audience." Bear in mind that by no means do I reject the idea that the lede should be significantly easier to digest than the body; I'm only saying that the lede cannot take the place of a Chem 101 textbook. I'm moving toward accepting the idea no one would even glance at this article unless they were studying chemistry, and anyone who was studying chemistry would have the resources at hand to fill in the blanks. So here are my conditions:

1. I Support only the User:Itub/ADC lead lede.
2. I take on board earlier comments that laymen and even some Chem 101 students might believe "strong" is purely and simply a synonym for "corrosive". With this in mind, I would suggest rewording the first sentence in order to move the wikilinks to strong acid and weak acid to the fore. Of course then the wikilinks in the later paragraphs of the lede would be un-wikilinked. NOTE: My terminology will be imprecise/flatly wrong. This is just the idea of it:

   An acid dissociation constant, K_a, (also known as acidity constant, or acid-ionization constant) is a quantitative measure of the strength of an acid in solution. When converted to a logarithmic scale, it is used as the measure which distinguishes weak acids from strong acids.

3. I suggest simply removing the following sentences. They certainly do not have any unity with the rest of the paragraph. Their position is misleading; it makes the first sentence seem to be topic sentence. I'm thinking they don't even need to be in the lede at all though:

   pK_a values can be experimentally determined by potentiometric (pH) titration, but for values of pK_a less than about 2 or more than about 11 spectrophotometric or NMR measurements may be required. The latter methods are preferred with non-protic solvents.

• That's all. Good luck. Ling.Nut ^{(talk—WP:3IAR)} 13:51, 4 December 2008 (UTC)

Thank you for your conditional support. About the sentences you suggest removing: I agree that that paragraph lacks cohesion, as it resulted from merging fragments from different paragraphs. However, I think it is important to include them somewhere in the lead, because they are the only sentences that discuss how the ADC is measured, which is a key part of the article. I'll think about other places where these sentences can be placed, but I welcome suggestions. --Itub (talk) 14:01, 4 December 2008 (UTC)

---

• Comment. I think the new lead is a good step towards explaining a bit more to non-chemist readers. However, it is now too long. I think the best solution is to explain more but include less details on polyprotic acids, thermodynamics, and buffers, which although related are not necessary to give the general reader an idea of what the acid dissociation constant is, what it is good for, and where does it come from (basically, the "what", "why", and "how"). I've posted a suggested trimmed version of the lead at User:Itub/ADC lead. --Itub (talk) 10:40, 4 December 2008 (UTC)

I would support with this lede. It concisely places of the topic in context, as required. The WTF factor has been removed. William Avery (talk) 15:44, 5 December 2008 (UTC)

• New oppose. It is great to see editors working on technical articles and some fantastic work has gone into this article. I would love to support it, but I have to agree with Proteins and others that it doesn't meet the standards for our very best work yet. The prose is reasonable and there are many moments of clarity, but the quality is patchy, and overall the prose is not engaging or of a professional standard. The coverage is good, although it possibly goes into too much detail, partly (I suspect) because the back-up articles are not very good, making the use of summary style difficult. For instance, Activity (chemistry) and Ionic strength are as clear as mud, yet essential to understand the meaning of parts of the article.

The topic of this article is not rocket science (well, some of it might be :-). I agree with User:Vassyana and others that this is bread and butter chemistry (not(?) literally :-), a simple and very important kind of equilibrium constant. It should be more accessible, and I think some reviewers without a scientific background have been generous and modest in supporting because they found the material out of reach. Having said that, I agree that much of this article will inevitably not be accessible to a reader without a scientific background, and the first section does make a decent effort to convey the basic idea to a general reader.

For me, the main problem is that the article is hard going for the scientifically literate, but nonspecialist, reader. This is no good, as such readers are prime audience for all but the most specialist parts of the article. The prose is a problem, and could really use a copyedit by a scientifically literate editor who is good at that. Judging by some remarks made above, they may also need a thick skin. I hesitate to comment on specifics when I see an editor told he is wrong that K_b is the inverse (reciprocal) of K_a, when in fact it is K_w/K_a with K_w approximately constant. This kind of "oversimplification" occurs in chemistry all the time. When measuring K_a in terms of concentrations rather than activities, a approximately constant quantity is being discarded, and activity (according to our article) is only dimensionless because the units are fixed. On the face of it, the definition of K_a in the lead is not dimensionless, so taking its logarithm is meaningless; again, units have been fixed. The article does explain some of these issues (the concentration of water is approximately constant).

However, contrary to the view that the article cannot be made clearer without dumbing down or oversimplifying, there are actually a few places where precision is lacking, and clarity with it. Anyway, ignoring the lead (which is too long and detailed - Itub's version is better), let me raise some specific issues.

• The equilibrium constant for this "dissociation" reaction is known as a dissociation constant. However, since the liberated proton combines with a water molecule to give a hydronium ion (also called oxonium), Arrhenius later proposed that the "dissociation" reaction should be written as an acid–base reaction. Why the quotes? This isn't use-mention distinction, and certainly not scare quotes. "dissociates" is quoted again later on, making me begin to feel sorry for this poor distrusted word :-)
• It also puts acids and bases on the same footing as being, respectively, donors or acceptors of protons. How can something which donates be on the same footing as something which accepts?
• In fact the bicarbonate ion is amphiprotic "In fact" adds nothing here. Also, water provides a simpler example.
• It is important to note that, in the context of solution chemistry, a "proton" is understood to mean a solvated hydrogen ion. In aqueous solution the "proton" is a solvated hydronium ion. Don't note what is being noted. Also when I checked the references I did not see them using the word "proton" to mean solvated hydrogen ion. For instance, in water, care is taken to distinguish between the donated proton and the solvated hydronium ion it is part of.
• For the specific equilibrium between a monoprotic acid, HA and its conjugate base A−, in water Why mention monoprotic here? Polyprotic acids also have this equilibrium - only several of them.
• Activities of the products are placed in the numerator, activities of the reactants are placed in the denominator. Since it is an equilibrium, "product" and "reactant" are not terribly precise. What is meant here is that, for the dissociation constant, the products of dissociation are in the numerator. Cf. the later discussion about association constants, which are essentially the reciprocal.
• In the case of VO2+(aq), the vanadium is octahedral, 6-coordinate, whereas all the other species are tetrahedral, 4-coordinate. "6-coordinate" presumably refers to 6 water molecules around the ion with an overall octahedral geometry. I had to figure that out for myself, though. The link helped a bit.
• VO₂⁺⇌ H₃VO₄ + H⁺. There appear to be some water molecules missing here.
• DMSO is widely used as an alternative to water. Yikes, I hope not :-)
• The apparently unlikely geminal diol Apparent to whom?
• The reason for this is that when the solvent is in its standard state its activity is defined as one. For example, the standard state of water:dioxane 9:1 is precisely that solvent mixture, with no added solutes. To obtain the pKa value for use with aqueous solutions it has to be extrapolated to zero co-solvent concentration from values obtained from various co-solvent mixtures. Neither brilliant prose, nor clear and precise.
• These facts are obscured by the omission of the solvent... How dare they!
• Ascorbic acid is an example of this effect. No, it is an example of an acid. Suggest "exhibits this effect"?
• Structural effects can also be important. The difference between fumaric acid and maleic acid is a classic example. Another imprecision in weak prose.
• The first point to note is that when pKa is positive Unencyclopedic prose construction.
• including those for protein-ligand equilibria Relevance? I also think Proton affinity is a bit of a stretch.

I hope the above late comments are helpful, and can be taken in the spirit of a peer review. It seems to me to be likely that this FAC will be closed soon anyway. Good luck improving the article. I hope it will be featured in the future. Geometry guy 16:18, 6 December 2008 (UTC)

How can you say "the prose is not ... of a professional standard"? I can accept that you may not like my style. That's one thing. It's quite another to impugn my professional integrity. Petergans (talk) 21:45, 6 December 2008 (UTC)

That is a misunderstanding. The "of professional standard" clause in the criteria refers to professional standards of copyediting. It has absolutely nothing to do with content or professional integrity. And actually, I do like your style. Much of the article is very good, but it needs copyediting. Geometry guy 22:13, 6 December 2008 (UTC)

The above discussion is preserved as an archive. Please do not modify it. No further edits should be made to this page.