At chemical equilibrium, the sum of chemical potentials weighted by each reaction's stoichiometric coefficients vanishes.
A chemical system is out of local chemical equilibrium when reaction adjustment cannot keep pace with transport, imposed changes or external driving. Comparing the chemical relaxation time with transport and irradiation times identifies plausible departures. Disequilibrium chemistry in an exoplanet atmosphere combines this principle with mixing, horizontal advection and atmospheric photochemistry.
For one particle species in chemical equilibrium under , chemical balance gives , hence . Elastic imposes no such constraint. In an expanding universe the number-changing reaction must remain fast compared with the Hubble parameter; after chemical freeze-out a nonzero chemical potential can develop even if elastic collisions maintain kinetic equilibrium.
The chemical relaxation time estimates how rapidly a perturbed abundance returns toward chemical equilibrium. Comparing it with the eddy mixing time identifies a chemical quench level.
The chemical potential of photons in thermal equilibrium is zero because their number is not conserved.
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Chemical equilibrium is a state in a reversible chemical reaction where the rates of the forward and reverse reactions are equal, resulting in no net change in the concentrations of the reactants and products over time. At this point, the concentrations of all species remain constant, although they are not necessarily equal. Key characteristics of chemical equilibrium include: 1. **Dynamic Condition**: Even though the concentrations of reactants and products remain constant, the reactions are still occurring.
