Théorie cinétique de l’équilibre chimique

Abstract

Willard Gibbs formulated in 1873 a mathematical function, the Gibbs energy, whose variation governs the perfect gas evolution. In 1895, Ludwig Boltzmann presented a microscopic description of the perfect gas in concordance with the phenomenological approach of Gibbs. The chemical thermodynamics has been historically developed using the model of the perfect gas from the existence of the chemical potential postulated in 1876 by Gibbs. The chemical potential, a quantity ascribed to every chemical species, represents the driving force of a chemical reaction. Chemists and physicists use since the beginning of the 20th century Gibbs and Boltzmann model to express the evolution laws of chemical reactions and phase transitions. This model, which presents a weakness to describe certain systems so-called as not ideal systems, was gradually declined in numerous successive empirical models of complexities and increasing predictive performances but restricted to particular systems. A unified model of microscopic evolutions based on kinetics is presented in this manuscript which is a clearly-cut breakthrough with thermodynamic chemistry: the existence of the chemical potential is not recognized and the calorimetric entropy from the second law of thermodynamics, which is consistent for heat transfer prediction, is not consistent to predict microscopic evolutions. Kinetic entropy rising from this approach replaces calorimetric entropy in the function that governs chemical reactions and phases equilibria evolutions.

Keywords

• <i>Boltzmann</i>
• Cinétique
• Collision
• Entropie
• Équilibre
• Second principe
• Thermodynamique