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Pourbaix diagram of iron. [1] The Y axis corresponds to voltage potential. 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.
While lists of noble metals can differ, they tend to cluster around gold and the six platinum group metals: ruthenium, rhodium, palladium, osmium, iridium, and platinum. In addition to this term's function as a compound noun , there are circumstances where noble is used as an adjective for the noun metal .
Pourbiax diagrams will show the phases that a material will take in an aqueous environment, based on electrical potential and pH. The brain maintains a pH of around 7.2 to 7.4, and from the Pourbaix diagram of platinum [ 3 ] it can be seen that at around 0.8 volts Pt at the surface will oxidize to PtO 2 , and at around 1.6 volts, PtO 2 will ...
Marcel Pourbaix (16 September 1904 – 28 September 1998) was a Belgian chemist and pianist. [citation needed] He performed his most well known research at the University of Brussels, studying corrosion. [1] His biggest achievement is the derivation of potential-pH, better known as “Pourbaix Diagrams”.
The conditions necessary, but not sufficient, for passivation are recorded in Pourbaix diagrams. Some corrosion inhibitors help the formation of a passivation layer on the surface of the metals to which they are applied. Some compounds, dissolved in solutions (chromates, molybdates) form non-reactive and low solubility films on metal surfaces.
The platinum-group metals [a] (PGMs) are six noble, precious metallic elements clustered together in the periodic table. These elements are all transition metals in the d-block (groups 8, 9, and 10, periods 5 and 6). [1] The six platinum-group metals are ruthenium, rhodium, palladium, osmium, iridium, and platinum.
During the early development of electrochemistry, researchers used the normal hydrogen electrode as their standard for zero potential. This was convenient because it could actually be constructed by "[immersing] a platinum electrode into a solution of 1 N strong acid and [bubbling] hydrogen gas through the solution at about 1 atm pressure".
Similar to Pourbaix diagrams for the speciation of redox species as a function of the redox potential and the pH, ionic partition diagrams indicate in which phase an acid or a base is predominantly present in a biphasic system as a function of the Galvani potential difference between the two phases and the pH of the aqueous solution.