The previous results demonstrated that the lateral interactions have a substantial impact on the thermophysical properties of adsorbates and, thence, the free energies of the system. In this section, we aim to disentangle the enthalpic and entropic contributions to the coverage-dependent free energy. Figure shows van't Hoff diagrams of the equilibrium constant of the CO adsorption on Pt(111) and Co(0001). For the CO/Pt(111) system, the lateral interactions are only repulsive, increasing the free energy of formation and decreasing the equilibrium constant. A coverage-dependent entropy has only modest effects on the equilibrium constant (see Figure ).