Entropy generation in a chemical reaction

TL;DR

This paper analyzes entropy generation in chemical reactions using simplified thermodynamic approaches, demonstrating that entropy production is always positive and linking it to microscopic fluctuations, without relying on complex non-equilibrium formalism.

Contribution

It introduces accessible methods for analyzing entropy generation in chemical reactions, connecting macroscopic entropy production to microscopic particle fluctuations.

Findings

Entropy production is always positive in chemical reactions.

Near-equilibrium reactions generate entropy greater than zero.

Entropy generation relates to microscopic particle fluctuations.

Abstract

Entropy generation in a chemical reaction is analyzed without using the general formalism of non-equilibrium thermodynamics at a level adequate for advanced undergraduates. In a first approach to the problem, the phenomenological kinetic equation of an elementary first order reaction is used to show that entropy production is always positive. A second approach assumes that the reaction is near equilibrium to prove that the entropy generated is always greater than zero, without any reference to the kinetics of the reaction. Finally, it is shown that entropy generation is related to fluctuations in the number of particles at equilibrium, i.e. it is associated to a microscopic process.