Linear combinations, Lagrange multipliers and Legendre transforms a look at three methods to write the Gibbs energy of reactive mixtures

A comparison of three methods to write the Gibbs energy: the algebraic procedure to obtain the transformed composition variables introduced by Barbosa and Doherty, the classical non-stoichiometric formulation discussed by Smith and Missen, and the use of Legendre transformations suggested by Alberty. This paper is the second member of a tetralogy conceived to give insight into the concept of microscopic reversibility.