engleski

Theories of colloid chemistry based on the point charge double layer model and their experimental verification

The most important and fundamental processes in colloid chemistry and in physical chemistry of electrolytes are theoretically explained on the basis of the point charge model for ions in double layer and in electrolyte solutions. The same theories are supported by relevant experiments from prominent laboratories from all over the world. They explain the following processes: variation of activity coefficients with electrolyte concentration, (an extension and replacement of the Debye-Hückel theory (to be published, see the oral contribution), electrokinetic phenomena on colloidal particles and in membranes, stability conditions of colloidal particles, counter and constituent ion adsorption on silver iodide, counter ion coagulation kinetics of silver iodide aggregates of hundreds of singlets observed by light scattering, “isoelectric” coagulation kinetics, i.e., coagulation of silver iodide with silver ions, peptization of aged and coagulated silver iodide, ion exchange in coagulation, counter ion coagulation kinetics of latex aggregates of up to six singlets aproof that coagulation is a second order reaction, criticism of Smoluchowski's coagulation theory, heterogeneous exchange of precipitates and amalgams and formation of colloidal crystals. The present poster demonstrates graphically that all theoretical functions deduced on the basis of the point charge double layer models are supported quantitatively by the corresponding experiments published by scientists from all over the world and cited as references in the following three review papers by the author. (1) Ion Exchange Theory of Coagulation and its Experimental Verification, Croat. Chem. Acta, 42(1970)161-142. (2) Experimental Electrokinetic Systems and the Point Charge Double Layer Model, Ibid., 67(1994)493-508. (3) Theories of Colloid Chemistry Based on the Point Charge Double Layer Model, Ibid., 69(1996)125-175). The main experimental techniques applied are: potentiometric determination of adsorption of constituent ions on precipitates, potentiometry of electrodes of first and second order, counter ion exchange and adsorption by the radioactive tracer technique, counter ion and isoelectric coagulation kinetics observed by light scattering and counter ion coagulation of latices observed by the single light scattering technique, heterogeneous exchange of precipitates and amalgams, electrokinetic studies and studies of the impedance of electrodes. Theoretical and experimental arguments are offered that as a rule all conventional theories in colloid chemistry must be rejected because not a single of their postulates has ever been supported by experiments. The conventional theories are based on the homogeneous electrical charge double layer model. The same model cannot be valid for colloidal particles because it has been developed exclusively for processes on polarized metallic electrodes of Galvanic cells. Although colloidal particles are isolators as organic latices, semiconductors as ionic solids and exceptionally metallic conductors they are all charged with fixed ions, i. e., adsorbed ions and chemically bound ionic radicals.The best model for them is the point charge double layer model.

colloid chemistry; theories

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