A classical density functional theory (DFT) that reduces to the perturbed chain statistical associating fluid theory equation of state has been implemented. This DFT implementation allows the use of molecular and binary interaction parameters fitted to the vapor–liquid equilibria of pure compounds and binary mixtures, respectively. Different functionals of dispersion forces are investigated and applied to the calculation of interfacial tension and adsorption of pure gases and their mixtures. The predictions of interfacial tension have been compared with both molecular simulations and experimental data, and good agreements have been seen. The DFT approaches also show good performance in correlating and predicting gas adsorption, and they are further compared with the multicomponent potential theory of adsorption and other DFT approaches available in the literature.