Martina Costa Reis

A continuum thermodynamical approach to electrochemical systems

This work focuses on formulating constitutive models for the bulk and double layer regions of an electrochemical system based on the fundamentals of modern continuum thermodynamics. Particularly, the constitutive models proposed accounting for transport phenomena in electrochemical systems by emphasizing the possibility of cross-coupling between two or more phenomena. Upon deriving a set of thermodynamic restrictions from the Müller-Liu approach of the second law of thermodynamics and axioms of constitutive theory, non-equilibrium quantities are examined in detail, and constitutive answers of the bulk and double layer regions are discussed. Moreover, the conditions for the thermodynamic equilibrium are evaluated for each region as well as the occurrence of dissipative mechanisms. Besides offering a proper formulation for non-equilibrium electrochemical systems, the approach described in this work can be easily extended to more complex chemical systems.

Reactive Continuum Mixtures under the Influence of Electromagnetic Fields

In this work, we present the equations of balance of mass, linear and angular momenta, energy, and entropy for reactive continuum mixtures under the influence of electromagnetic fields. We assume that the mixture is a polar continuum whose constituents are electric charge and/or electric dipole moment carriers immersed in a Newtonian fluid. From the mass balance equation, properties of real and potential electrolytes were related to the terms of mass production. In addition, from the linear and angular momenta balances, it was shown that the stress tensor is not symmetric due to the polar nature of both the constituents and the mixture. Moreover, the energy balance equation for the mixture reveals that the energy flux vector should not be interpreted as the heat flux vector from the classical continuum mechanics. The balance laws presented in this work may offer a theoretical tool to investigate mass transport and thermoelectric phenomena in electrolyte solutions as well as in bio and geological fluids.

Entropy and its mathematical properties: consequences for thermodynamics

In this work, a comprehensive meaning for entropy is provided on the basis of foundations of information theory and statistical thermodynamics. For this purpose, the close relation between missing information and entropy is presented by emphasizing their probabilistic nature. Furthermore, the physical implications of the mathematical properties of the entropy function are exploited using the elementary notions of differential and integral calculus. Particularly, it is evidenced that the usual thermodynamic inequalities found in many textbooks of physical chemistry are direct consequences of the concavity of entropy. The aim of this work is to show that many concepts presented in textbooks of physical chemistry can be obtained in a simple and mathematically clear way.

Lyapunov Stability Criteria for Reacting Ionic Fluid Flows

In this work, the stability of reacting ionic fluid flows is studied by using the Lyapunov direct method. For this purpose, one considers the flow of a reacting ionic fluid inside a bounded domain under the action of external sources. The Lyapunov candidate function characteristic for this kind of fluid depends on the barycentric velocity of the fluid, mass concentration, temperature, pressure, and electromagnetic fields. Nevertheless, whenever more strict physical conditions are imposed to the reacting ionic fluid flow, the obtained Lyapunov candidate function is identical to a well-known thermodynamic potential of classical thermodynamics.

Non-equilibrium thermodynamic model for calcium carbonate supersaturated solutions of high salinity

Based on principles of non-equilibrium thermodynamics, the behavior of calcium carbonate supersaturated solutions of high salinity is studied. For this purpose, these solutions are treated as continuous media whose physicochemical properties change in space and time. Furthermore, by exploiting the Müller–Liu formulation for the second law of thermodynamics, one recognizes which thermodynamic forces are responsible for keeping the

A segunda lei da termodinâmica

CaCO_{3}

A two-fluid model for reactive dilute solid–liquid mixtures with phase changes

CaCO3 supersaturated solutions out of equilibrium. The obtained results suggest that intermolecular interaction forces play an important role in the dynamics of solution, as well as in the mass transport of solutes. Particularly, from the estimated values for the self-diffusion and mutual diffusion coefficients of NaCl(aq),