The 'H' stands for hydrogen, although other standards may be used, and they are for room temperature only. The vertical axis is labeled E H for the voltage potential with respect to the standard hydrogen electrode (SHE) as calculated by the Nernst equation. Pourbaix diagrams are also known as E H-pH diagrams due to the labeling of the two axes. The Pourbaix diagram for uranium in a non-complexing aqueous medium (e.g. The diagrams are named after Marcel Pourbaix (1904–1998), the Russian-born Belgian chemist who invented them. Based on the Pourbaix diagram of Ti (Figure 2(a)), TiO 2+ ion is a favorite formation when pH value is lower than 2.3 and voltage is higher than 0.2 V (SHE) at 25☌. The Pourbaix diagram is useful to simplify the complex reactions. Pourbaix diagrams are commonly given at room temperature, atmospheric pressure, and molar concentrations of 10 −6 and changing any of these parameters will yield a different diagram. Immersing titanium in electrolyte causes complex reactions with 16 forms of Ti ions and oxides. Beside potential and pH, the equilibrium concentrations are also dependent upon, e.g., temperature, pressure, and concentration. Similarly to phase diagrams, they do not allow for reaction rate or kinetic effects. electrode potentials (tin, titanium), it will be particularly important to. As such a Pourbaix diagram can be read much like a standard phase diagram with a different set of axes. ( 1) For the purposes envisaged by Pourbaixs diagrams one can assume that. Boundaries (50 %/50 %) between the predominant chemical species (aqueous ions in solution, or solid phases) are represented by lines. In electrochemistry, and more generally in solution chemistry, a Pourbaix diagram, also known as a potential/pH diagram, E H–pH diagram or a pE/pH diagram, is a plot of possible thermodynamically stable phases ( i.e., at chemical equilibrium) of an aqueous electrochemical system. The Y axis corresponds to voltage potential.

Titanium pourbaix diagram