Onsager Reciprocal Relations in Thermodynamics

The Onsager reciprocal relations are fundamental to non-equilibrium thermodynamics, describing the relationship between thermodynamic fluxes and forces. These principles, based on local equilibrium and microscopic reversibility, are essential for predicting system behavior and transport phenomena. They impact fields like physical chemistry and are integral to technological advancements in energy and thermal systems.

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Understanding the Onsager Reciprocal Relations in Thermodynamics

The Onsager reciprocal relations are a pivotal concept in non-equilibrium thermodynamics, often considered an extension of classical thermodynamic principles. These relations describe the interplay between various thermodynamic fluxes and forces in a system that is not at global equilibrium but can be assumed to be in local equilibrium. This local equilibrium hypothesis allows for the definition of thermodynamic properties at the microscopic scale, even as the system undergoes dynamic changes. The Onsager relations are derived from statistical mechanics and rely on the principle of microscopic reversibility, which assumes no external time-reversal symmetry-breaking fields, such as magnetic fields, are present.
Laboratory with cylindrical metal calorimeter, beaker with water and ice on digital scale, chemical glassware on light bench.

The Mathematical Framework of Onsager's Theorem

Onsager's theorem is articulated through the symmetry of the coefficients that relate thermodynamic fluxes to their conjugate forces. For any pair of fluxes and forces, such as those related to energy, mass, entropy, or particle number, Onsager's theorem posits that the cross-coefficients are equal when the system is close to equilibrium. Mathematically, this means that the coefficient relating the flux of one variable to the force of another is equal to the coefficient relating the flux of the second variable to the force of the first. This symmetry facilitates the prediction of system responses to external perturbations and is fundamental for understanding transport phenomena in non-equilibrium systems.

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1

Onsager relations context: equilibrium type?

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Apply to systems not at global equilibrium but assuming local equilibrium.

2

Onsager relations foundation: originating theory?

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Derived from statistical mechanics principles.

3

Onsager relations assumption: external fields?

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Assume no external time-reversal symmetry-breaking fields, like magnetic fields.

4

The theorem by ______ ensures that cross-coefficients for variables like energy or particle number are ______ when a system is near equilibrium.

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Onsager equal

5

Onsager reciprocal relations - definition

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Mathematical expressions stating that certain coefficients relating fluxes and forces in irreversible processes are equal in reciprocal situations.

6

Role of Onsager's relations in non-equilibrium systems

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Provide predictive power for system behavior when deviating from equilibrium, crucial for understanding and controlling such systems.

7

Practical applications of Onsager's work

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Influences design of chemical reactors, thermal management, and optimization of energy transfer in engineering and technology.

8

The book ______ by ______ and ______ is a resource for understanding the thermodynamics of quantum information.

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Quantum Thermodynamics: An Introduction to the Thermodynamics of Quantum Information Sebastian Deffner Steve Campbell

9

______ wrote 'Four Laws That Drive the Universe', which explains thermodynamic principles including ______'s contributions.

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Peter Atkins Onsager

10

For a deeper exploration of thermodynamics, one can read '______' by ______ and ______ Goldstein.

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The Refrigerator and the Universe Martin Inge F.

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