Proposal of a new principle of thermodynamics

Michel Denis (1)

1 UR - Université de Rennes

Kinetics and thermodynamics are largely disconnected in current theories because Arrhenius activation energies (Ea) have strictly no influence on equilibrium distributions. A first step towards the incorporation of rate theories in thermodynamics was the identification of the pre-exponential term of the Arrhenius equation as an entropic quantity. The second step examined here is the possible contribution of Ea in equilibrium landscapes. Interestingly, this possibility exists if envisioning the energetic exponential term of rates constants as the probability that the energy of the reactant is sufficient for the transition. Under this assumption, the energetic exponent of the equilibrium constant Kji takes the form (1 − Hi/Hj)(1 + Ea(i→j)/Hi) where H are the mean enthalpies of the reactants. This alternative treatment solves several inconsistencies, predicts that activation energies decrease with temperature, integrates activation energies in the detailed balance and modifies equilibrium relationships in heterogeneous systems, while letting unchanged the Maxwell-Boltzmann distribution. These probabilistic rate constants are then reintroduced in dynamic systems to provide them with the two distinct facets of time: the time step and the time arrow.

Mots clés: Kinetics; equilibrium; heat capacity; en- thalpy; entropy; Gibbs free energy

Domaines: Thermique [physics.class-ph]

Michel Denis. Proposal of a new principle of thermodynamics. 2017. ⟨hal-01569569v2⟩