<abstract xmlns="http://www.w3.org/1999/xhtml"> Probable values of the degree of ion-pairing (ion-association) of aqueous solutions of alkali metal and ammonium peroxodisulfates have been calculated for various estimated values of association constants, in dependence a) on the concentration of the binary solution, b) on the concentration of the other electrolyte in the polycomponent solution with the common ion, able or not able to form ion pair, and c) on the value of the activity quotient <italic>Q</italic>a. It followed that in the presence of another component with a common cation and neglecting the influence of activity coefficients, the ion-association degree of peroxodisulfate α <italic>> </italic>0.5 in solutions with total molality <italic>m</italic>t > 0.1 mol kg-1; as mostly <italic>Q</italic>a &lt; 1.0, the ion-association degree is even higher so that in such cases the alkali metal and ammonium peroxodisulfates can prevailingly behave as uni-univalent electrolytes. In agreement with these results, evaluation of the solubility of sodium, potassium and ammonium peroxodisulfates in some ternary and quaternary systems has been performed under the simplified assumption of a complete ion-association to MS2O81- ions. It has been shown that the mean deviations between the calculated and observed solubilities of the crystallizing components are almost equally low as under the assumption of a total dissociation of the corresponding substances. The results indicated that the prevailing ion-association of more concentrated solutions of peroxodisufates could be taken as an acceptable approach for the quantitative evaluation of physico-chemical behaviour of systems containing peroxodisulfates.</abstract>

Probable values of the degree of ion-pairing (ion-association) of aqueous solutions of alkali metal and ammonium peroxodisulfates have been calculated for various estimated values of association constants, in dependence a) on the concentration of the binary solution, b) on the concentration of the other electrolyte in the polycomponent solution with the common ion, able or not able to form ion pair, and c) on the value of the activity quotient Qa. It followed that in the presence of another component with a common cation and neglecting the influence of activity coefficients, the ion-association degree of peroxodisulfate α > 0.5 in solutions with total molality mt > 0.1 mol kg-1; as mostly Qa < 1.0, the ion-association degree is even higher so that in such cases the alkali metal and ammonium peroxodisulfates can prevailingly behave as uni-univalent electrolytes. In agreement with these results, evaluation of the solubility of sodium, potassium and ammonium peroxodisulfates in some ternary and quaternary systems has been performed under the simplified assumption of a complete ion-association to MS2O81- ions. It has been shown that the mean deviations between the calculated and observed solubilities of the crystallizing components are almost equally low as under the assumption of a total dissociation of the corresponding substances. The results indicated that the prevailing ion-association of more concentrated solutions of peroxodisufates could be taken as an acceptable approach for the quantitative evaluation of physico-chemical behaviour of systems containing peroxodisulfates.

Ion-pairing in aqueous solutions of peroxodisulfates

Heřmanova 35, 17000 Prague 7, Czech Republic

Acta Chimica Slovaca

{"article-title":"Ion-pairing in aqueous solutions of peroxodisulfates"}

Probable values of the degree of ion-pairing (ion-association) of aqueous solutions of alkali metal and ammonium peroxodisulfates have been calculated for...

Ion-pairing in aqueous solutions of peroxodisulfates

Publié en ligne: 14 déc. 2012

Pages: 180 - 185

DOI: https://doi.org/10.2478/v10188-012-0028-9

Mots clés
Ion-pairing, Degree of ion-association, Alkali metal peroxodisulfates, Ammonium peroxodisulfate, Evaluation of solubility

This content is open access.

Ion-pairing in aqueous solutions of peroxodisulfates

Publié en ligne: 14 déc. 2012

Pages: 180 - 185

DOI: https://doi.org/10.2478/v10188-012-0028-9

Mots clésIon-pairing, Degree of ion-association, Alkali metal peroxodisulfates, Ammonium peroxodisulfate, Evaluation of solubility

This content is open access.

Mots clés
Ion-pairing, Degree of ion-association, Alkali metal peroxodisulfates, Ammonium peroxodisulfate, Evaluation of solubility