Talk:pH

Areas of improvement

I identified several areas for improvement that I believe will improve the readability, accessibility, and comprehensiveness of the article. Firstly, to update the page on its application, I will increase the number of real-world examples in the article to help readers understand the practical applications of pH in various fields. This will make the content more engaging and accessible to readers who do not have a background in chemistry or science. I'll add clear subheadings to make the article easier to navigate and understand. This will help readers find the information they need faster while also making the content more organized. Finally, in order to improve the clarity of the images, I'll go over the images in the article and revise their captions to provide more detail and context for the reader. I'll also look for ways to include more diverse images that show how pH can be used in real-world situations. Veggietaquito (talk) 04:15, 12 March 2023 (UTC)

For chemists, comprehensiveness of the chemical parts of the article is very high. But for non-chemical audience adding the  examples of practical application  for "real-world" cases may be useful for the improvement of readability  . ChemEdit (talk) 13:44, 20 March 2023 (UTC)

You cannot log something with a unit/dimension. You either log the absolute value, or you log the concentration/activity divided by some reference concentration/activity. Compare dB (decibel). The reason is that log can be substituted by its MacLaurin series and otherwise you would end up with a sum of dimensionless + unit + unit squared + unit cubed and so on. 83.223.9.100 (talk) 08:43, 27 April 2023 (UTC)

I'm mildly surprised to see " An alternative method of measuring pH is using an electronic pH meter" as if this is not the standard and people who work with water chemistry as part of their job are out there staring at what color the water is, hoping to pase out the ph that way. This seems more like a something students in a lab would be doing as opposed to a day-to-day thing. Maybe I'm wrong, but in my line of work everyone uses an electronic meter. Beeblebrox (talk) 19:06, 4 October 2023 (UTC)

At the very beginning of this, the "p" is said to be "potential", and this is internally linked to "electric potential". This is misleading (notwithstanding that later it is linked to an electric potential in an electrochemical cell in "hydrogen electrode"). The original "p" was short for the German word "Potenz", meaning "potency". "Potential" is OK in English, meaning the inherent ability to do something - low pH means likely to corrode, dissolve, etc. Bobgid (talk) 18:48, 30 March 2024 (UTC)

p[H] subsection

For the p{H} subsection, wouldn't it be more appropriate to have the title "p_H." ? Since we are basing off this pH definition from Soresen and he defines it as such, not p[H]. Veggietaquito (talk) 17:29, 14 April 2023 (UTC)

Only if you're very careful with your typography! A lower case p with a subscripted H looks awfully like a big P in front of a smaller H! Since "pH" is always printed like that, I think it more sensible to leave it as p[H], where the "p" is funtioning as a sort of mathematical operator: "minus log(10) of", and the [H] is what it's operating on. Also used frequently in pOH, pCl, p[acetate], etc. Bobgid (talk) 19:00, 30 March 2024 (UTC)

pH of seawater

I've stumbled over this sentence in this article: The pH of seawater is typically limited to a range between 7.4 and 8.5. as the value of 7.4 seemed way too low to me. This sentence actually talks about extremes of pH value rather than describing what the "normal" range is. The same sentence is currently also at seawater and at ocean and I plan to change it in all three places (am pondering if the same info really should be in 3 articles though; see below). I've contacted an ocean chemistry expert about this sentence (Tim Jickells) and he recommended changed it like this: The pH value at the surface of oceans is normally about 8.2 and can fall to 7.8 in deep ocean waters as a result of degradation of organic matter in these waters (Emerson and Hedges chapter 4) and can be as high as 8.4 in surface waters in areas of high biological productivity (Chester and Jickells Chapter 9).. Does anyone object? He also said "I think chasing extreme pH values is probably misleading". Pinging User:Plumbago who has worked on this before. Also pinging User:Epipelagic and User:ASRASR.

I think this whole pH thing in the ocean is so important now because ocean acidification results in a dropping pH value so it's important to get all the facts straight and clear.

My second question is: would the info about the pH value in the ocean perhaps be better off centralised in one article and then the other articles should refer across, rather than repeating the same info in several places? At the moment, the same/similar about current pH value info would be in these articles: pH, sea, ocean, seawater, ocean acidification. Can we envision any streamlining for this? Maybe by using excerpts? As the pH value will continue to drop over time (even if slowly), this will be an ongoing issue. EMsmile (talk) 12:41, 2 May 2023 (UTC)

I've now removed that sentence in question and modified the section a bit. I've updated the content about a drop in pH value by copying some sentences from ocean acidification which were recently updated there. I'll now also update the equivalent content at sea, ocean, seawater. EMsmile (talk) 07:32, 3 May 2023 (UTC)

Thanks for this. I think Jickells' revised sentence is good. According to NOAA (https://www.noaa.gov/education/resource-collections/ocean-coasts/ocean-acidification#:~:text=Because%20of%20human%2Ddriven%20increased,the%20ocean%20becomes%20more%20acidic) the average pH of the oceans has dropped to 8.1 over the past 100 years. Setting up excerpts to the relevant WP articles is a good idea in order to create consistency. ASRASR (talk) 22:56, 22 May 2023 (UTC)

0 to 14

I'm no subject expert but after reading the cited source "Negative pH Does Exist" and the lead's mention that pH can fall outside [0, 14], I felt confident enough to make this edit that removes reference to 0 and 14 as bounds. The first text removed contains information found elsewhere in the article (relationship to hydrogen ions; logs mean tenfold difference is a pH difference of 1). Then some rewording on 7 as neutral.

The article could still do a better job of explaining whether a pH of 7 exactly is or isn't true neutral (or whether it depends on some other factor like temperature), and maybe cover this [0, 14] misconception in the body of the article with some examples outside this interval. — Bilorv (talk) 08:47, 9 August 2023 (UTC)

I've added this back to the lead "The pH range is commonly given as zero to 14" - I think it's useful to have this as these are the "normal" limits (isn't it?) and anything that is below zero or above 14 is very rare, right? And I think we should probably explain this a bit better in the main text. EMsmile (talk) 14:28, 14 August 2023 (UTC)

But it's false. NaOH and HNO₃ are pretty common reagents, including at the concentrations required to get out of the [0, 14] range.

What is true is that as you get beyond the usual range, pH stops being a good measure. For example, at such high concentrations, activity and concentration can no longer be assumed equal. Double sharp (talk) 08:00, 9 December 2023 (UTC)

Hi! I am a retired research chemist and teacher of chemistry at varios levels. You seem to think negative pH is uncommon, rare. It isn't. You also need to understand the ifference between "strong" and "concentrated" and to keep these terms separate. In a teaching lab, there are often racks of common reagent dilute solutions, and to simplify proportion-judging, they are of similat concentrations, typically 2 mol/litre. Thus "dilute Hydrochloric acid" will be 2M, but sulfuric acid will be 1M (as it dissociates one H2SO4 giving two H+). Not really "concentrated", and activity still close to molarity. Now minus log10 of 2 is minus 0.3, so there's a negative pH. (most pH test strips would show "zero", really meaning "below 0.5") Many household chemicals in solution would reach that too, eg, "pH Reducer" for pools/spas.Agreed, at higher concentrations, activity not equal molarity. But 10M acids are easy (pH approx -1), but 100M acids are not (even neat water is only 1000/18 = 55.6M). 100M would be -2, so the scale must give out somewhere between -1 and -2, and similarly at the other end of the scale. Things get really weird in non-aqueous solutions, so don't go there! Regards, Bob. Bobgid (talk) 15:24, 30 March 2024 (UTC)