Field of Science

pH Potpouri

The term pH has been in use for nearly a century. It is a logarithmic measure of the hydrogen ion concentration ([H+]): pH = -log10[H+]. (Technically, there aren't bare protons (H+) floating around in solutions, but that's another post!) The original symbol was pH. and introduced by Sörensen in 1909. Theories vary as to the origin of the p - all agree it means power but whether in Latin, French or German, seems in dispute. I would hazard it was either German or Latin as the original paper was published in German (Biochem. Zeitschr.). If I were not on the road, I'd look it up.

The modern form pH was introduced in 1920, "as a matter of typographical convenience".


  1. I understood that pH stood for pouvoir hydrogene (powers of hydrogen). Hope you enjoy Chicago ACS. My trip got yanked out from under me.

  2. I always write pH! Never than less isn't better to say is the base 10 negative log of the hydrogen ion activity {H+}?

    I think that what hydrogen sensitive electrodes measures.


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