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1. Introduction
Equilibrium calculations show whether a chemical or electrochemical reaction may proceed or not. No information is given about the rate of the reaction, that is, its kinetics. However, increasing temperature and thereby usually faster reaction rates, cause diagrams based on only thermodynamic considerations to be more relevant.
In a phase stability diagram of predominant area, the area of stability of a chemical species is delimited by lines of equilibrium in which the value of the Gibbs free energy is zero. The characteristics of such lines (slope and ordinate to the origin) are based on chemical reactions where the chemical species is present as a reactant or product, since his area of stability may be surrounded by the area of stability of other chemical species which are also involved in reaction (closed stability area) or the area may be defined only at one side and open towards infinite stability conditions (open stability area).
For definition of equilibrium lines in a phase stability diagram, a chemical system is treated mathematically as a set of equations where each chemical reaction corresponds to a mathematical equation, equating to zero the sum of...