Pierre Van Rysselberghe

Reaction Rates and Affinities

A new definition of elementary reactions is being based upon the Marcelin‐De Donder formulation of reaction rates. Complex reactions resulting from sequences of elementary reactions are examined, under steady‐state conditions, both close to, and far from equilibrium. In the former case the over‐all rate is proportional to the over‐all affinity, while in the latter case, when all steps are far from their equilibria, the over‐all rate varies exponentially with the over‐all forward affinity. The problem of the identification of rate‐determining steps is discussed on the basis of the adopted definition of elementary reactions. Application of the treatment to the two‐step sequence A + B⇌C, C→D+E leads to a close connection with the absolute rate theory.

General Reciprocity Relation between the Rates and Affinities of Simultaneous Chemical Reactions

A derivation of the general reciprocity relation ∂v1/∂A2=∂v2/∂A1 between the rates and affinities of simultaneous chemical reactions is presented. The Onsager symmetry relation L12=L21 between mutual influence coefficients is obtained in the limiting case of the linear relations between rates and affinities valid in the neighborhood of equilibrium.

Rationale of the transfer coefficients of electrode kinetics

Abstract A brief discussion implying definitions of the following concepts is presented: anodic and cathodic overvoltage factors, charge number, stoichiometric numbers, anodic and cathodic transfer coefficients, affinity factor. True transfer cofficients are shown always to add up to unity.

The Limiting Laws of the Interionic Attraction Theory of Strong Electrolytes

The various methods of obtaining the limiting laws of strong electrolytes are briefly discussed. It is shown that the dependence of these limiting laws on the temperature, the dielectric constant of the solvent and the volume of the solution can be deduced from the Gibbs‐Helmholtz equation and the virial theorem of Clausius. The Debye‐Huckel and the Kramers limiting laws are found to be of the same type as these general limiting laws, with numerical coefficients obtained thanks to the use of the Poisson equation.

On the Splitting of Entropy Production Terms into Flux and Force Factors

It is suggested that irreversible processes obeying phenomenological laws such as Ficks diffusion law, Fouriers heat conductivity law, etc., be treated, in the thermodynamics of irreversible processes, with phenomenological coefficients coinciding with those appearing in these laws (Ficks diffusion coefficient, Fouriers heat conductivity coefficient, etc.) and with accordingly modified mutual influence coefficients, even though the corresponding fluxes and forces are then different from the actual flows in space (diffusion flow, heat flow, etc.) and their conjugate forces.

On the definition of pH

Resume Certaines suggestions anterieures concernant la definition du pH aux basses et aux hautes forces ioniques sont examinees plus avant et comparees a certains aspects du rapport sur la standardisation du pH par BATES ET GUGGENHETM.