Pourbaix diagram

The conditions necessary (but not sufficient) for passivation are recorded in Pourbaix diagrams.

The Pourbaix diagram in the image shows that titanium is actually thermodynamically a very reactive metal.

As such a Pourbaix diagram can be read much like a standard phase diagram with a different set of axes.

The effect of pH is summarized using Pourbaix diagrams, but many other factors are influential.

Pourbaix diagrams are widely used to describe the chemical behaviour of chemical species in the hydrosphere.

According to the Pourbaix diagram for iron, the metal is passive when the pH is above 9.5.

The lines in the Pourbaix diagram show the equilibrium conditions, that is, where the activities are equal, for the species on each side of that line.

Pourbaix diagrams have several uses, for example in corrosion studies, geology and in environmental studies.

The following is the Pourbaix diagram for chromium in pure water, perchloric acid or sodium hydroxide:

Pourbaix diagrams are also known as E-pH diagrams due to the labeling of the two axes.

The simplified reactions, listed in the next column, can also be read in detail from the Pourbaix diagrams of the considered element in water.

The Pourbaix diagram for vanadium in water, which shows the redox potentials between various vanadium species in different oxidation states is also complex.

A simplified Pourbaix diagram indicates regions of "Immunity", "Corrosion" and "Passivity", instead of the stable species.

It is clear from the Pourbaix diagram below that lead is more likely to corrode in a citrate medium than it is in a non-complexing medium.

The interactions of carbonate anions with uranium(VI) cause the Pourbaix diagram to change greatly when the medium is changed from water to a carbonate containing solution.

In the Pourbaix diagram for uranium, the limits of stability of water are marked by the two dashed green lines, and the stability region for water falls between these lines.

In chemistry, a Pourbaix diagram, also known as a potential/pH diagram, E-pH diagram or a pE/pH diagram, maps out possible stable (equilibrium) phases of an aqueous electrochemical system.

In a Pourbaix diagram, the acidity is plotted on the x axis using the pH scale, while how oxidising/reducing nature of the system is plotted on the y axis in terms of volts relative to the standard hydrogen electrode.