MadSci Network: Science History

Re: who discovered pH and when and how?

Date: Tue Mar 9 16:05:58 1999
Posted By: Michael Onken, Grad Student, Wash U
Area of science: Science History
ID: 920385874.Sh

There are two answers to this question, depending on what you meant:

  1. Sören Sörenson coined the term "PH" (which was later converted to "pH") in 1909, to represent the exponential power (-log) of the concentration of Hydrogen ions (which he termed "CH", now symbolized as [H+]).

  2. Svante Arrhenius theorized in1887 that all electrolytes (salts) dissociate in water to yield positive and negative ions. He correlated his findings to acids, stating that all acids in aqueous solution dissociate to yield a hydrogen ion (H+). His findings first introduced the dependence of acidity/alkalinity on hydrogen ion concentration.

Each man's work toward understanding the importance of hydrogen ions in solutions followed the works of J. Willard Gibbs, who first described the thermodynamics of liquids in 1876, and François-Marie Raoult, who extended Gibbs' findings in 1886 by characterizing the contribution of concentrations of solutes to the thermodynamics of solutions.

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