Thus, it is crucial to accurately know the thermochemical quantities of species participating in the reactions to make quantitative predictions with kinetic models. In microkinetic models (gasphase or surface reaction mechanism), thermophysical properties of all species and intermediates are required to determine the equilibrium constants of the elementary steps. Commonly, an elementary reaction is specified in the forward direction with rate constant k fwd and the rate constant for the reverse direction k rev is determined from the concentration equilibrium constant K c ,