Download/Embed scientific diagram | Diagrama de Pourbaix del hierro  y voltaje en función del pH (línea azul). from publication: Síntesis de nanopartículas. Download scientific diagram | Diagrama de Pourbaix para especies de cloro considerando una [Cl-] TOT = mM a T = 25°C para la ferrita de manganeso . ESPECIE. ΔG° (cal/mol). Pb. 0. PbO. , Pb3O4. , Pb2O3. , PbO2. , Pb2+. -5, Pb4+. 72, H2O. , REACCIONES DE.
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Retrieved from ” https: The reaction equation is:. 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.
Diagrama de Pourbaix
For the simple case of a thermodynamic system consisting of a metal M and water, various reaction equations may be written having the form:. This will vary with temperature.
Similarly to phase diagrams, they do not allow for reaction rate or kinetic effects.
As a function of temperature. Pourbaix diagrams are widely used to describe the chemical behaviour of chemical species in the hydrosphere.
Geological Survey water-Supply Paper From Wikipedia, the free encyclopedia. Using the Nernst equation as above, but with an E 0 of 1. For instance, carbonate has a great effect upon the diagram for uranium.
The “H” stands digramas hydrogen, although other standards may be used, and they are for room temperature only.
The reaction equation is written:. As such a Pourbaix diagram can be read much like a standard phase diagram with a different set of axes. In these cases, pE is used instead of E H. On either side of the line, one form of the species will instead be said to be predominant.
Pourbaix diagram – Wikipedia
Above this line, water will be oxidized to form oxygen gas, and it will usually not be possible to pass beyond this line as long as there is still water present to be oxidized. In many cases, the possible conditions in a system are limited by the stability region of water. Passivation occurs when the metal forms a stable coating of an oxide or other salt on its surface, the best example being the relative stability of aluminium because of the alumina layer formed on its surface when exposed to fe.
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. Vertical, horizontal, and sloped. Using the Pourbaix diagram correctly will help shed light not only on the nature of the species present in the solution or sample but may also help to understand the pournaix mechanism.
Archived from the original on 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. The diagrams also pourbais not take kinetic effects into account, meaning that species shown as unstable might not react to any significant degree in practice.
In other projects Wikimedia Commons. United States Government Printing Office. The diagrams are named after Marcel Pourbaix —the Russian -born, Belgian chemist who invented them. See diagrams at right. Using the expressions for the free energy in terms of potentials, the energy balance diagraas given by a Nernst equation:. Wikimedia Commons has media related to Pourbaix diagrams. There are three types of line boundaries in a Pourbaix diagram: This page was last edited on 26 Decemberat The same values should poudbaix used for all species present in the system.
The presence of trace amounts of certain species such as chloride ions can also greatly affect the stability of certain species by destroying passivating layers. The equation must be balanced for M, H, O and charge. While such diagrams can be drawn for any chemical system, it is important to note that the addition of a metal binding agent ligand will often modify the diagram.