History
The concept of p was first introduced by Danish chemist Søren Peder Lauritz Sørensen at the Carlsberg Laboratory in 1909 and revised to the modern pH in 1924 to accommodate definitions and measurements in terms of electrochemical cells. In the first papers, the notation had the "H" as a subscript to the lowercase "p", like so: pH.
The exact meaning of the "p" in "pH" is disputed, but according to the Carlsberg Foundation pH stands for "power of hydrogen". It has also been suggested that the "p" stands for the German Potenz (meaning "power"), others refer to French puissance (also meaning "power", based on the fact that the Carlsberg Laboratory was French-speaking); others refer to "potential". Other suggestions have surfaced over the years that the "p" stands for the Latin terms pondus hydrogenii, potentia hydrogenii, or potential hydrogen. It is also suggested that Sørensen used the letters "p" and "q" (commonly paired letters in mathematics) simply to label the test solution (p) and the reference solution (q).
Current usage in chemistry is that p stands for "decimal cologarithm of", as also in the term pK, used for acid dissociation constants.
Read more about this topic: Negative P H
Famous quotes containing the word history:
“Man watches his history on the screen with apathy and an occasional passing flicker of horror or indignation.”
—Conor Cruise O’Brien (b. 1917)
“My good friends, this is the second time in our history that there has come back from Germany to Downing Street peace with honour. I believe it is peace for our time. We thank you from the bottom of our hearts. And now I recommend you to go home and sleep quietly in your beds.”
—Neville Chamberlain (1869–1940)
“Humankind has understood history as a series of battles because, to this day, it regards conflict as the central facet of life.”
—Anton Pavlovich Chekhov (1860–1904)