Talk:Henderson–Hasselbalch equation

The calculator link at the bottom of the article
I use McAfee SiteAdvisor. It's a tool that will show small icons in form of a green, yellow, or red checkmark (or X) next to the list of websites that come up whenever you use a search engine, like Google. The point of the tool is to warn users about sites that send spammy emails, or have "red downloads" i.e. downloads that contain viruses, or sites that contain programs that take over your browser.

The link to the calculator has a yellow icon, because, according to the analysis provided on McAfee's site, after entering your email address on the site, it sends about 3.3 spammy emails a month.

You can see the analysis here: 

Therefore, I think that the calculator link should be removed. An encyclopedia shouldn't direct it's users to questionable sites like that.

Also, if you're interested, the McAfee tool is free. It's really useful in identifying questionable or even dangerous websites. (And no, I don't work for McAfee.)


 * Or you could just avoid entering your E-Mail address...

Nomenclature
Posted by an anon, moved here by SocratesJedi:

Help! I don't know anything about Wikipedia, but the name of this page is blatantly misspelled. The correct spelling is Henderson-Hasselbach (without the antepenultimate letter 'l') as you can easily verify with a google search. Would someone more knowledgeable please rename the page and references therein (e.g. the calculator at bottom of article). Thanks!


 * Actually this has been discussed before and I thought that this was correct before, but it appears that both spellings are in common usage, but that balch is more common than bach (check google scholar results), Balch outnumbers Bach by about a factor of 2x. In any case the bach spelling redirects here already, so no worries.  I'd be nice to know what the actual scientist's name was, if we can run it down.  Anyone?  -SocratesJedi | Talk 00:51, 2 December 2005 (UTC)


 * I have done a search through the Chemical Abstract Service on Hasselbalch, Haselba(l)ch, and Hasselbach in the early 1900's (the equation was published in 1916 in relation to carbonic acid and acidosis). There is a K. A. Hasselba(l)ch active at that time publishing papers on metabolic acidosis and acid/base systems; there are no other authors active at the time doing acid-base work (although there are authors with similar names).  Of the citations I found, 11 are cited to K. A. Hasselbalch and 6 are cited to K. A. Hasselbach.  This is a rather unfortunate result...Perhaps we should just stick a line in that says it's spelled both ways.  I have copies of those citations if anyone wants them (email me, leave something on my talk page) - it's copyvio to paste them wholesale into Wikipedia. --  stillnotelf   has a talk page  19:22, 2 December 2005 (UTC)
 * (later thought) I will attempt to go through these papers later and track down exactly which one it was when Hasselba(l)ch invented the equation - I don't have time right now. --  stillnotelf   has a talk page  19:28, 2 December 2005 (UTC)
 * (even later thought) He might have been part of the exodus of European scientists who came to America to escape WWI, perhaps he changed his name along the way. --  stillnotelf   has a talk page  21:42, 2 December 2005 (UTC)

"Hasselhoff equation"
The Henderson-Hasselbalch equation is commonly referred to as the David Hasselhoff equation - I'm an undergraduate student and confirmed this information with professors and online. That addition is NOT vandalism and is useful to students who have forgotten the equation's true identity. Reverting back to that version. Dcteas17 00:26, 8 February 2006 (UTC)


 * After meeting you on Talk:College of William and Mary, I feel obliged to ask if it was Dr. Landino who said that? --  stillnotelf   has a talk page  20:08, 8 February 2006 (UTC)


 * She was the first person I heard it from. I then Googled it and found more than a few Chemistry review sheets posted by other professors with 'only' Hasselhoff mentiones (i.e., "use the Hasselhoff equation...") Daniel 18:42, 9 February 2006 (UTC)


 * I do not find strong evidence for this. "Hasselhoff Equation" yields on 15 google returns.  If professors are using this, cite names and academic affiliations or show substantial website hits or actual publications using this terminology. -SocratesJedi | Talk 23:07, 9 February 2006 (UTC)


 * I think they're mostly independent re-inventions...I never personally heard Dr. Landino call it the Hasselhoff equation, but it sounds like something she'd've done--I've heard her randomly bring up Hasselhoff in other contexts. I'm going to have to weakly agree that it's not particularly encyclopedic or verifiable.  HOWEVER, it might be a good idea to set up Henderson-Hasselhoff equation et cetera as redirects to the proper page?  This would help lost students.  --  stillnotelf   has a talk page  04:38, 10 February 2006 (UTC)


 * Aye, this is something with which I can agree. I would strongly support those redirects and perhaps will help create them tomorrow.  -SocratesJedi | Talk 07:11, 10 February 2006 (UTC)


 * I support the redirects, Stillnotelf...good idea. And thanks for putting them in SocratesJedi.  The only reason I entered it in was so that people who couldn't remember it would be able to find it. Daniel 01:27, 11 February 2006 (UTC)


 * Created Henderson-Hasselhoff, Hasselhoff equation, and Henderson-Hasselhoff equation--any others? -- stillnotelf   has a talk page  03:35, 11 February 2006 (UTC)


 * Sounds good. Thanks again.  Daniel 13:52, 11 February 2006 (UTC)

Misspelling
What is the reference which supports that "Hasselbalch" is frequently misspelled "Hasselbach"? --HappyCamper 17:42, 21 November 2006 (UTC)


 * I don't know of any reference, but you can verify it by searching Google or Chemical Abstracts as discussed above. Itub 19:29, 21 November 2006 (UTC)
 * I don't see any proof that it's misspelled. The sources that the user cited contradicted each other.  The consensus seemed to be that it was spelled both ways and there is no way of knowing which is right. --Phoenix Hacker (talk) 04:31, 21 February 2008 (UTC)

References or further reading
I changed the classification of some works previously given as "References" to "Further reading", because they lack wp:in-line citations to avail the reader to check what claims they actually substantiate. Still, if anyone knows their proper in-line citation locations in the article text, it would be appreciated if they could be wiki-formatted like the entry currently given in the "Reference" section. Mikael Häggström (talk) 19:40, 31 July 2011 (UTC)

Wikiproject Medicine
I have listed the page under Wikiproject Medicine. This equation is of practical application in Medicine and Pharmacology. I would request users to rewrite portions and add relevant information pertaining to these areas as well.  D ip ta ns hu Talk 06:52, 17 December 2012 (UTC)
 * I have removed the tag for WP:MED but retained the tag for Wikiproject Pharmacolgy. The article still requires certain inputs.  D ip ta ns hu Talk 15:56, 16 February 2013 (UTC)

log
it is a bit strange that it changes suddenly from log to log10. given that log is generally accepted as meaning log10 — Preceding unsigned comment added by 193.63.43.34 (talk) 11:23, 15 March 2013 (UTC) I believe that in may fields/contexts log is assumed to denote the natural log.Eaberry (talk) 18:13, 31 January 2014 (UTC)


 * On the continent ln is the natural one, log the Brigg's one, but in English-speaking countries, alas, log is often understood to be the natural one.137.205.183.82 (talk) 15:48, 7 April 2015 (UTC)

"Limitations" paragraph
I would argue that these are not limitations of the equation itself, but cautions concerning its use. The only approximation I can see is the assumption that activities are proportional to concentration. If a solution contains 1 mM of the acid and 1 uM of its conjugate base, then the pH will in fact be 3 units below the pKa, as predicted by the equation. However if you take neutral distilled water and add 1 mM of acid and 1 uM of the base, you will in general not achieve these concentrations in solution because titrating the water from neutrality to the final pH will require a significant amount of H+ or OH-, and this will come from the acid-base pair.Eaberry (talk) 22:47, 30 January 2014 (UTC)

Derivation
Has a hilarious mistake in it, but I'm not gonna bother, as adding quality to Wikipedia is a mug's job.137.205.183.82 (talk) 15:47, 7 April 2015 (UTC)

pCO2 * KhCO2 = [CO2] !
Hello, please, you indicated in the "estimation of blood pH" section that :


 * $$ [\mathrm{H}_2\mathrm{CO}_3] = k_{\rm H~CO_2}\, \times p_{\mathrm{CO}_2},$$

but, normally:


 * $$ [\mathrm{CO}_2] = k_{\rm H~CO_2}\, \times p_{\mathrm{CO}_2},$$

so, what's the relationship between [CO2] and [H2CO3] ? why are they necessarily equal ? — Preceding unsigned comment added by 154.107.204.150 (talk) 22:40, 27 April 2016 (UTC)

Heylman equation
I noticed this problem as I'm removing references to Cram101 aka Content Technologies as they copy Wikipedia. Such a book citation was supporting the statement "A second form of the equation, known as the Heylman–Lardinois equation, expressed in terms of ...". I removed the book, but couldn't find this equation. I found "Lardinois" was added in March 2016, so I removed it (it was correctly removed in May by a new user, but User:Melcous reverted, then was removed again in October when it was called a prank, but added back this January). Then I found the Herschel equation is also not verifiable! It was added in 2012 but also appears in no reliable sources I can find.

Major re-write
The whole article has been re-written. A proper derivation of the title equation is given, including explicit statements of the approximations involved. Extraneous, trivial and irrelevant content has been removed. Petergans (talk) 14:25, 14 January 2019 (UTC)

Clearer presentation
The way the article is now, it clearly explains under what assumptions the Henderson-Hasselbalch equation holds which is great. However, it is not until the third section that the reader finds out what the equation actually is which is probably what most readers want to know. Therefore, I think that it should be stated in the beginning what the equation looks like (similar to here) and then afterwards how it is derived. I also think that we can afford to show in a bit of detail how to derive the equation from the dissociation constant. I actually incorporated those edits, but they appear to be more controversial than I thought. You have been working a lot on the article. What do you think? --Inc (talk) 09:05, 4 May 2019 (UTC)
 * The H-H equation is all but obsolete. Its value is extremely limited by the assumptions on which it is based; for example, it cannot be used for dibasic organic acids.
 * The only significant assumption that needs to be made today is that variation of activity factors can be ignored. Constant temperature is taken for granted in all calculations that use equilibrium constant values. There are many widely available spreadsheets and computer packages for calculating speciation that don't require simplifying assumtions. The H-H equation is of historical interest. Modern textbooks on analytical chemistry only give it a passing mention. That's why I chose this form of presentation. Petergans (talk) 16:50, 4 May 2019 (UTC)
 * Well, I am sure that there are better ways nowaday, but it is still being taught from the high school level, so it is of some interest and the equation is a good way to introduce students to basic concepts. However, regardless of whether it is being used or not, do you not think it is generally better to introduce the equation early in the article when that equation is the whole topic of the article? --Inc (talk) 19:27, 1 June 2019 (UTC)
 * Inc, you make a good point. I will put something in the lead which will address it. Petergans (talk) 21:20, 1 June 2019 (UTC)

=

Final rewrite
I cannot find a reference for the equation $$ \mathrm{pH} = 6.1 + \log_{10} \left ( \frac{[\mathrm{HCO}_3^-]}{0.0307 \times P_{\mathrm{CO}_2}} \right ),$$ so am unable to specify the temperature at which it applies. Is it 25 or 37C? Petergans (talk) 16:23, 3 March 2022 (UTC)

Wiki Education assignment: Biochemistry I
— Assignment last updated by Lanatarik (talk) 21:47, 25 April 2023 (UTC)

PDF in the Derivation, assumptions and limitations section
I think keeping the duplicate pdf link might be a copyright violation @Dirac66

WP:COPYVIOEL

if it isn't, then I think it should just be made the actual citation instead of having 2 duplicates Yawing Gunman (talk) 05:29, 7 February 2024 (UTC)


 * I have now deleted this superfluous PDF. Dirac66 (talk) 12:43, 7 February 2024 (UTC)