The variation of the dipole moment of adsorbed particles with the fraction of the surface covered

Publisher Website
Google Scholar
Abstract
The statistical treatment which was given previously to determine the variation of the heat of adsorption of polar molecules is extended to show how the variation of the dipole moment with the fraction of the surface covered can be taken into account. The equations have been used to determine the variation of the heat of adsorption of ammonia on a non-conducting surface. The contributions to the heat of adsorption due to the van der Waals and to the electrostatic forces are of the same order of magnitude and of opposite signs so that the resultant variation in the heat of adsorption is very much less than would be expected from a consideration of forces of one kind only. The contributions to the heat of adsorption, which are made by the electrostatic forces when the dipole moment is constant and equal to M0, when it is constant and equal to M1, and when its variation with the fraction of the surface covered is taken into account, are compared for the whole range of values of θ. It is shown that the mutual depolarizing action of the molecules reduces the magnitude of the total variation in the heat of adsorption by a considerable amount. The heat curve which is calculated from the equations given by the statistical analysis is compared with that which is obtained when it is assumed that the particles form a random distribution over the surface, and the effect of the clustering of the adsorbed particles on the surface on the variation of the heat of adsorption is determined.

This publication has 14 references indexed in Scilit: