The article was not promoted by User:SandyGeorgia 23:04, 25 October 2008 [1].
The concept acid dissociation constant is of major importance in chemistry, physics, earth sciences (including environmental sciences) and biology (including human biology) and is also important in other areas such as the development of new pharmaceuticals and all sorts of industrial processes where acidity has to be controlled. The article presents a comprehensive coverage of the topic and indicates the main areas of application. It should therefore be of interest to a wide range of the readership.
The topic is covered, at an elementary level, in all text-books on general chemistry, though the treatment is usually simplified. The simplifications are explained in this article.
I have been active in research in this subject area since 1972. Our programs Hyperquad are the world market leaders for the determination of acid dissociation constants and stability constants of metal complexes with ligand acids. Correspondence with users of this software has given me an appreciation of the range of applications of interest in research today. This is reflected in the structure of the article.
I am confident that if this article is accepted for featured status that it will enhance the reputation of Wikipedia among scientists and science students.
Petergans ( talk) 09:21, 9 October 2008 (UTC) reply
Comments
The first line of the lead reads "An acid dissociation constant (aka acidity constant, acid-ionization constant) is an equilibrium constant for the dissociation of an acid". If the reader does not already have some grasp of the linked concepts, then I suspect the article will be completely unintelligible to him/her. The links put these concepts on a more rigorous basis. The need to address a more elementary-level reader is a recurrent theme for technical articles like this one and it is difficult to resolve. We have pitched the intro level towards a school student studying chemistry and coming across this idea for the first time.
I take the point about risk assessment and will insert something about it in the importance section. Petergans ( talk) 14:45, 10 October 2008 (UTC) reply
There is a problem here: in common usage the terms "pKa" and "acid dissociation constant" are used (wrongly!) almost interchangably. I think that we would have to say something along the lines of - the stronger the acid the larger the values of Ka and the smaller the value of pKa - but to me this sounds a bit confusing. In practice pKa values are used much more often than Ka values, but I don't see how this can be reflected in the article title. Petergans ( talk) 18:45, 10 October 2008 (UTC) reply
These are very helpful comments, thank you very much. I shall be away for the next two weeks so I will get round to dealing with them and others that will come in when I return. Petergans ( talk) 18:45, 10 October 2008 (UTC) reply
As a Chemistry Education major, though not an expert by any means (precipitates is one of my weaker areas), all the major problems I see can be summarized into three arguments:
This user does not appear to have read the article properly; there is a complete section entitled Experimental determination of pKa values with a link to a more detailed article Determination of equilibrium constants. Petergans ( talk) 08:53, 11 October 2008 (UTC) reply
The details are in Avdeef's book, reference 42. Petergans ( talk) 08:53, 11 October 2008 (UTC) reply
I don't understand this comment. There are many examples showing how the concept of pKa can be applied to derive useful information. Petergans ( talk) 08:53, 11 October 2008 (UTC) reply
I've modified it in the light of comments. Does it need further work? Petergans ( talk) 11:05, 11 October 2008 (UTC) reply
Added the reference and an example at acid dissociation constant #Importance of pKa values
The title "Acid dissociation constant" accurately describes the content of the article, whereas "Acidity constant" is meaningful only in a specific context which identifies it as a dissociation constant. Petergans ( talk) 13:49, 17 October 2008 (UTC) reply
Remember that Wikipedia is not a textbook: "Wikipedia is an encyclopedic reference, not a textbook. The purpose of Wikipedia is to present facts, not to teach subject matter. It is not appropriate to create or edit articles that read as textbooks, with leading questions and systematic problem solutions as examples. These belong on our sister projects Wikibooks and Wikisource. Other kinds of examples, specifically those intended to inform rather than to instruct, may be appropriate for inclusion in a Wikipedia article."
As I see it, the difference between a textbook and an encyclopedia article is that while the encyclopedia hopes to "tell the whole truth" about one topic, the textbook has much more space, can start from the basics, teach concepts in a sequence that is useful for learning, can include plenty of examples and even exercises, and can hide some of the ugly facts that are not essential for an introduction. Some may complain that this article is just useful if the reader already knows about the topic. That may be true, but this is acceptable IMHO because an encyclopedia is a reference work. Those who really know nothing about chemistry will be much better served by reading a general chemistry textbook. -- Itub ( talk) 07:56, 13 October 2008 (UTC) reply
Comments. I have little knowledge of chemistry so please excuse any misreadings based on ignorance. I am assuming that a reader of this article would be expected to have some prior knowledge of modern chemistry, since this is not the first article a novice would look at. With that in mind, here are some thoughts.
I will post notes section by section, since it will probably take me a day or three to get through the article. These first notes are all from the definitions section.
I'm on holiday in Crete, but here are some quick answers.
Petergans (
talk) 14:38, 20 October 2008 (UTC) A general point: "reference to equation (1) above" would be fine if all the equations were numbered as they would be in a paper published in a chemical journal. Unfortunately, it is not normal practice to number equations in WP, where a more discursive style is preferred. Some guidance on numbering of equations would be welcome.
Petergans (
talk) 08:18, 25 October 2008 (UTC)
reply
In Lowry-Bronsted theory every acid has a conjugate base and every base has a conjugate acid. It is therefore to some extent arbitrary which partner is denoted as conjugate. But you are right, some clarification is needed. Petergans ( talk) 14:38, 20 October 2008 (UTC) reply
The definitions section has been modified in the light of these comments. Petergans ( talk) 09:27, 25 October 2008 (UTC) reply
Hydration means the addition of water; it is the concentration of water which is constant. Will attempt a clarification next week. Petergans ( talk) 14:38, 20 October 2008 (UTC) reply
It is common practice to use the term "fully dissociated" when in fact the the difference from 100% dissociation is finite, but very small. See hydrochloric acid below. Petergans ( talk) 14:38, 20 October 2008 (UTC) reply
This is a subtle point that needs attention. The phenomenon is that in a given solvent all acids with pK less than a certain value are classed as strong acids, hence they are brought to the same level of strength. In another solvent a particular acid may be weak or vice versa. Likewise all bases with a pK value greater than a certain value are classed as strong bases. Petergans ( talk) 14:38, 20 October 2008 (UTC) reply
-- Mike Christie (talk) 02:31, 20 October 2008 (UTC) reply
The "Equilibrium constant" section has now been revised. I have re-instated the struck o notation as I believe that the IUPAC recommendation for the sign for standard is the
plimsol line and this o is the nearest I could get to it. I am basing this on
Quantities, Units and Symbols in Physical Chemistry, page 5. We are currently looking into this to see if the recommendation still stands.
Petergans (
talk) 16:55, 25 October 2008 (UTC)
reply
More comments:
I agree. The table was introduced by another editor (eaglefalconn) who, though a major stimulus to bringing the article to FAC status, has disappeared into thin air. I didn't want to offend him, but I did think that the table is superfluous. I will start to make corrections after I return to Leeds on Friday. Petergans ( talk) 11:21, 21 October 2008 (UTC) reply
I've reviewed everything but the last two subsections and should return to those tomorrow. -- Mike Christie (talk) 02:35, 21 October 2008 (UTC) reply
More comments:
It is standard practice in chemistry to give hazard warnings in appropriate places. Is this not appropriate? I didn't want some adventurous schoolboy to think that it is safe to play with cyanide. Please advise. Petergans ( talk) 11:44, 22 October 2008 (UTC) reply
-- Mike Christie (talk) 01:44, 22 October 2008 (UTC) reply
We saw the bullet/list comment coming (See http://en.wikipedia.org/wiki/Talk:Acid_dissociation_constant#Another_round_of_editing) and I sandboxed various other ways of presenting the material. The problem with running the text together, which I tried, is that most of the applications are so disparate, the area of applications is so broad, that the resulting text will not make sense; in effect most of the applications only have pK in common. Would separate paragraphs be acceptable?
Regarding the use of the {{ main}} template, this is an error of inex-Wiki-sperience. The point we were trying to make is that applications linked in that way are substantial topics in their own right. Petergans ( talk) 11:44, 22 October 2008 (UTC) reply
The article was not promoted by User:SandyGeorgia 23:04, 25 October 2008 [1].
The concept acid dissociation constant is of major importance in chemistry, physics, earth sciences (including environmental sciences) and biology (including human biology) and is also important in other areas such as the development of new pharmaceuticals and all sorts of industrial processes where acidity has to be controlled. The article presents a comprehensive coverage of the topic and indicates the main areas of application. It should therefore be of interest to a wide range of the readership.
The topic is covered, at an elementary level, in all text-books on general chemistry, though the treatment is usually simplified. The simplifications are explained in this article.
I have been active in research in this subject area since 1972. Our programs Hyperquad are the world market leaders for the determination of acid dissociation constants and stability constants of metal complexes with ligand acids. Correspondence with users of this software has given me an appreciation of the range of applications of interest in research today. This is reflected in the structure of the article.
I am confident that if this article is accepted for featured status that it will enhance the reputation of Wikipedia among scientists and science students.
Petergans ( talk) 09:21, 9 October 2008 (UTC) reply
Comments
The first line of the lead reads "An acid dissociation constant (aka acidity constant, acid-ionization constant) is an equilibrium constant for the dissociation of an acid". If the reader does not already have some grasp of the linked concepts, then I suspect the article will be completely unintelligible to him/her. The links put these concepts on a more rigorous basis. The need to address a more elementary-level reader is a recurrent theme for technical articles like this one and it is difficult to resolve. We have pitched the intro level towards a school student studying chemistry and coming across this idea for the first time.
I take the point about risk assessment and will insert something about it in the importance section. Petergans ( talk) 14:45, 10 October 2008 (UTC) reply
There is a problem here: in common usage the terms "pKa" and "acid dissociation constant" are used (wrongly!) almost interchangably. I think that we would have to say something along the lines of - the stronger the acid the larger the values of Ka and the smaller the value of pKa - but to me this sounds a bit confusing. In practice pKa values are used much more often than Ka values, but I don't see how this can be reflected in the article title. Petergans ( talk) 18:45, 10 October 2008 (UTC) reply
These are very helpful comments, thank you very much. I shall be away for the next two weeks so I will get round to dealing with them and others that will come in when I return. Petergans ( talk) 18:45, 10 October 2008 (UTC) reply
As a Chemistry Education major, though not an expert by any means (precipitates is one of my weaker areas), all the major problems I see can be summarized into three arguments:
This user does not appear to have read the article properly; there is a complete section entitled Experimental determination of pKa values with a link to a more detailed article Determination of equilibrium constants. Petergans ( talk) 08:53, 11 October 2008 (UTC) reply
The details are in Avdeef's book, reference 42. Petergans ( talk) 08:53, 11 October 2008 (UTC) reply
I don't understand this comment. There are many examples showing how the concept of pKa can be applied to derive useful information. Petergans ( talk) 08:53, 11 October 2008 (UTC) reply
I've modified it in the light of comments. Does it need further work? Petergans ( talk) 11:05, 11 October 2008 (UTC) reply
Added the reference and an example at acid dissociation constant #Importance of pKa values
The title "Acid dissociation constant" accurately describes the content of the article, whereas "Acidity constant" is meaningful only in a specific context which identifies it as a dissociation constant. Petergans ( talk) 13:49, 17 October 2008 (UTC) reply
Remember that Wikipedia is not a textbook: "Wikipedia is an encyclopedic reference, not a textbook. The purpose of Wikipedia is to present facts, not to teach subject matter. It is not appropriate to create or edit articles that read as textbooks, with leading questions and systematic problem solutions as examples. These belong on our sister projects Wikibooks and Wikisource. Other kinds of examples, specifically those intended to inform rather than to instruct, may be appropriate for inclusion in a Wikipedia article."
As I see it, the difference between a textbook and an encyclopedia article is that while the encyclopedia hopes to "tell the whole truth" about one topic, the textbook has much more space, can start from the basics, teach concepts in a sequence that is useful for learning, can include plenty of examples and even exercises, and can hide some of the ugly facts that are not essential for an introduction. Some may complain that this article is just useful if the reader already knows about the topic. That may be true, but this is acceptable IMHO because an encyclopedia is a reference work. Those who really know nothing about chemistry will be much better served by reading a general chemistry textbook. -- Itub ( talk) 07:56, 13 October 2008 (UTC) reply
Comments. I have little knowledge of chemistry so please excuse any misreadings based on ignorance. I am assuming that a reader of this article would be expected to have some prior knowledge of modern chemistry, since this is not the first article a novice would look at. With that in mind, here are some thoughts.
I will post notes section by section, since it will probably take me a day or three to get through the article. These first notes are all from the definitions section.
I'm on holiday in Crete, but here are some quick answers.
Petergans (
talk) 14:38, 20 October 2008 (UTC) A general point: "reference to equation (1) above" would be fine if all the equations were numbered as they would be in a paper published in a chemical journal. Unfortunately, it is not normal practice to number equations in WP, where a more discursive style is preferred. Some guidance on numbering of equations would be welcome.
Petergans (
talk) 08:18, 25 October 2008 (UTC)
reply
In Lowry-Bronsted theory every acid has a conjugate base and every base has a conjugate acid. It is therefore to some extent arbitrary which partner is denoted as conjugate. But you are right, some clarification is needed. Petergans ( talk) 14:38, 20 October 2008 (UTC) reply
The definitions section has been modified in the light of these comments. Petergans ( talk) 09:27, 25 October 2008 (UTC) reply
Hydration means the addition of water; it is the concentration of water which is constant. Will attempt a clarification next week. Petergans ( talk) 14:38, 20 October 2008 (UTC) reply
It is common practice to use the term "fully dissociated" when in fact the the difference from 100% dissociation is finite, but very small. See hydrochloric acid below. Petergans ( talk) 14:38, 20 October 2008 (UTC) reply
This is a subtle point that needs attention. The phenomenon is that in a given solvent all acids with pK less than a certain value are classed as strong acids, hence they are brought to the same level of strength. In another solvent a particular acid may be weak or vice versa. Likewise all bases with a pK value greater than a certain value are classed as strong bases. Petergans ( talk) 14:38, 20 October 2008 (UTC) reply
-- Mike Christie (talk) 02:31, 20 October 2008 (UTC) reply
The "Equilibrium constant" section has now been revised. I have re-instated the struck o notation as I believe that the IUPAC recommendation for the sign for standard is the
plimsol line and this o is the nearest I could get to it. I am basing this on
Quantities, Units and Symbols in Physical Chemistry, page 5. We are currently looking into this to see if the recommendation still stands.
Petergans (
talk) 16:55, 25 October 2008 (UTC)
reply
More comments:
I agree. The table was introduced by another editor (eaglefalconn) who, though a major stimulus to bringing the article to FAC status, has disappeared into thin air. I didn't want to offend him, but I did think that the table is superfluous. I will start to make corrections after I return to Leeds on Friday. Petergans ( talk) 11:21, 21 October 2008 (UTC) reply
I've reviewed everything but the last two subsections and should return to those tomorrow. -- Mike Christie (talk) 02:35, 21 October 2008 (UTC) reply
More comments:
It is standard practice in chemistry to give hazard warnings in appropriate places. Is this not appropriate? I didn't want some adventurous schoolboy to think that it is safe to play with cyanide. Please advise. Petergans ( talk) 11:44, 22 October 2008 (UTC) reply
-- Mike Christie (talk) 01:44, 22 October 2008 (UTC) reply
We saw the bullet/list comment coming (See http://en.wikipedia.org/wiki/Talk:Acid_dissociation_constant#Another_round_of_editing) and I sandboxed various other ways of presenting the material. The problem with running the text together, which I tried, is that most of the applications are so disparate, the area of applications is so broad, that the resulting text will not make sense; in effect most of the applications only have pK in common. Would separate paragraphs be acceptable?
Regarding the use of the {{ main}} template, this is an error of inex-Wiki-sperience. The point we were trying to make is that applications linked in that way are substantial topics in their own right. Petergans ( talk) 11:44, 22 October 2008 (UTC) reply