First pH meter was constructed in 1934 by Arnold Beckman. Glass pH electrode that have potential dependent on activity of H+ ions was constructed much earlier, in 1906 by Fritz Haber and Zygmunt Klemensiewicz, but the technical difficulties were preventing large scale use of potentiometric measurements of the pH (note that before 1909 pH was […]
pH electrode – flowing and gel
In flowing electrodes internal solution of KCl slowly flows to the outside through the junction – small hole with porous membrane, or ceramic or – in older models – asbestous wick. While such electrode contaminates solution with KCl it does it very slowly and traces of K+ and Cl– ions released during measurements are in […]
pH electrodes – construction
Most often used pH electrodes are glass electrodes. Typical model is made of a glass tube ending with a small glass bubble. Inside of the electrode is usually filled with buffered solution of chlorides in which silver wire covered with silver chloride is immersed. pH of internal solution varies – for example it can be […]