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Abstract--A relation was derived which describes negative adsorption (salt exclusion) in systems in which double layer interaction takes place but where the surface potential remains finite, such as in clay pastes and sediments. Exclusion volumes calculated for montmorillonite pastes in equilibrium with 1:1 type electrolytes were found to compare favorably with data obtained by F. A. M. de Haan in an earlier study.

A model describing the electric double layers in clay-electrolyte systems containing particles with different surface charge densities was developed and used to calculate the film thickness of water present in a clay paste. The average water film thicknesses (-18/~) calculated by considering the clay to contain 9 groups of particles of different charge densities did not differ from those calculated by assuming one average charge density; provided the minimum potential between particles remained constant. These values, however, were higher than those obtained from gravimetric water determinations by about 30%. The overestimation of the average thickness of the water films by the theoretical model is most likely due to the assumption of a complete parallel arrangement of particles in the paste and the validity of the Gouy theory for double layers on clays.

Para citar este artículo / To reference this article / Para citar este artigo Sandoval, M. J. y col. (2013). Estrategias didácticas para la enseñanza de la química en la educación superior. Educ. Educ. Vol. 16, No. 1, Química, aprendizaje activo, ingenierías, estrategias educativas, estudiante universitario. (Fuente: Tesauro de la Unesco). Marisa Julia Sandoval Palabras clave

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