The two-dimensional van der Waals constants of molecules adsorbed on charcoal and graphite

Abstract

Entropy data indicate that physically adsorbed molecules of many gases on charcoal or on graphite are mobile and freely rotating. This picture is in accordance with other data and it induced us to apply a two-dimensional van der Waals equation to the adsorption data. It is then found that the adsorbed molecules repel each other. Explaining this repulsion by the repulsion of dipoles, induced in the adsorbed molecules by the surface, we obtain dipole moments which are in accordance with data, found by Mignolet in similar cases. The picture of induced dipoles leads to an appreciable contribution towards the heat of adsorption. (auth)