Thermodynamic affinity in constrained free-energy systems

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Abstract

Abstract: Affinity is the generic measure of the deviation of a state from stable equilibrium. Affinity, as introduced by de Donder, is a thermodynamic state property defined in terms of p, T, and system composition during the course of a chemical change. When incorporating reaction kinetic constraints to minimization of Gibbs energy of a multiphase system, affinity can be followed in terms of the extents of the constrained reactions. This property then becomes calculated in terms of the constraint potentials received as additional Lagrange multipliers in the minimization routine. Thus, received affinities are consistent with the respective values calculated from the chemical potentials of the reactants and products of the constrained reactions and their limiting behaviour corresponds to that defined for both stationary and stable equilibrium states. The intermediate affinities can be used in the respective reaction rate calculations, or as input parameters, to define the local chemical equilibrium set by known reaction kinetic constraints. Thus, they become a useful concept in modelling reactive processes. Graphical abstract: [Figure not available: see fulltext.]

Original languageEnglish
Pages (from-to)381–394
Number of pages14
JournalMonatshefte für Chemie
Volume149
Issue number2
Early online date2017
DOIs
Publication statusPublished - 2018
MoE publication typeA1 Journal article-refereed

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Reaction kinetics
Free energy
Thermodynamics
Lagrange multipliers
Chemical potential
Gibbs free energy
Reaction rates
Chemical analysis

Keywords

  • CFE
  • Computational chemistry
  • Local thermodynamic equilibrium
  • Thermodynamics

Cite this

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title = "Thermodynamic affinity in constrained free-energy systems",
abstract = "Abstract: Affinity is the generic measure of the deviation of a state from stable equilibrium. Affinity, as introduced by de Donder, is a thermodynamic state property defined in terms of p, T, and system composition during the course of a chemical change. When incorporating reaction kinetic constraints to minimization of Gibbs energy of a multiphase system, affinity can be followed in terms of the extents of the constrained reactions. This property then becomes calculated in terms of the constraint potentials received as additional Lagrange multipliers in the minimization routine. Thus, received affinities are consistent with the respective values calculated from the chemical potentials of the reactants and products of the constrained reactions and their limiting behaviour corresponds to that defined for both stationary and stable equilibrium states. The intermediate affinities can be used in the respective reaction rate calculations, or as input parameters, to define the local chemical equilibrium set by known reaction kinetic constraints. Thus, they become a useful concept in modelling reactive processes. Graphical abstract: [Figure not available: see fulltext.]",
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}

Thermodynamic affinity in constrained free-energy systems. / Koukkari, Pertti; Pajarre, Risto; Kangas, Petteri.

In: Monatshefte für Chemie, Vol. 149, No. 2, 2018, p. 381–394.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Thermodynamic affinity in constrained free-energy systems

AU - Koukkari, Pertti

AU - Pajarre, Risto

AU - Kangas, Petteri

PY - 2018

Y1 - 2018

N2 - Abstract: Affinity is the generic measure of the deviation of a state from stable equilibrium. Affinity, as introduced by de Donder, is a thermodynamic state property defined in terms of p, T, and system composition during the course of a chemical change. When incorporating reaction kinetic constraints to minimization of Gibbs energy of a multiphase system, affinity can be followed in terms of the extents of the constrained reactions. This property then becomes calculated in terms of the constraint potentials received as additional Lagrange multipliers in the minimization routine. Thus, received affinities are consistent with the respective values calculated from the chemical potentials of the reactants and products of the constrained reactions and their limiting behaviour corresponds to that defined for both stationary and stable equilibrium states. The intermediate affinities can be used in the respective reaction rate calculations, or as input parameters, to define the local chemical equilibrium set by known reaction kinetic constraints. Thus, they become a useful concept in modelling reactive processes. Graphical abstract: [Figure not available: see fulltext.]

AB - Abstract: Affinity is the generic measure of the deviation of a state from stable equilibrium. Affinity, as introduced by de Donder, is a thermodynamic state property defined in terms of p, T, and system composition during the course of a chemical change. When incorporating reaction kinetic constraints to minimization of Gibbs energy of a multiphase system, affinity can be followed in terms of the extents of the constrained reactions. This property then becomes calculated in terms of the constraint potentials received as additional Lagrange multipliers in the minimization routine. Thus, received affinities are consistent with the respective values calculated from the chemical potentials of the reactants and products of the constrained reactions and their limiting behaviour corresponds to that defined for both stationary and stable equilibrium states. The intermediate affinities can be used in the respective reaction rate calculations, or as input parameters, to define the local chemical equilibrium set by known reaction kinetic constraints. Thus, they become a useful concept in modelling reactive processes. Graphical abstract: [Figure not available: see fulltext.]

KW - CFE

KW - Computational chemistry

KW - Local thermodynamic equilibrium

KW - Thermodynamics

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DO - 10.1007/s00706-017-2095-5

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JF - Monatshefte für Chemie

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