Re: xkcd: Unsolved Chemistry Problems

On 07/06/2024 22:55, Your Name wrote:

On 2024-06-07 21:30:55 +0000, Lynn McGuire said:

>
xkcd: Unsolved Chemistry Problems
    https://xkcd.com/2943/
>
Sounds like a good start to me.  I fight with ionic chemistry all the time in my job.
>
Explained at:
 https://www.explainxkcd.com/wiki/index.php/2943:_Unsolved_Chemistry_Problems
>
Lynn

 Solved the last one of those:
    "The letters pH stand for potential of hydrogen, since pH is
    effectively a measure of the concentration of hydrogen ions
    (that is, protons) in a substance."
 :-)

SPOILER ALERT
s'aktually an abbreviation of an abbreviation. It should be p[H+]
The "p" is used to denote the decimal negative logarithm of the following quantity; you can have p(tons of concrete) or p(the number of atoms in the universe), though I don't know why you might want to.
The square brackets nowadays mean the concentration of whatever is inside them in moles per liter, ie [H+] is the concentration of hydrogen ions in a sample.
And so p[H+] or more commonly pH is the negative logarithm of the concentration in moles per liter of +ve hydrogen ions in a sample.
The "p" does not stand for anything, contrary to many contrary opinions. Sorenson had the concept of negative logs, but the p in his symbol - a p with an individualised H subscript - referred to test tube p, with the unique H subscript meaning the negative log of the concentration of H ions.
pH was easier to print than (a range of) individualised subscripts, so quite quickly the p came to mean the negative log of the concentration of whatever.
:)
Peter Fairbrother