A conductance study of guanidinium chloride, thiocyanate, sulfate, and carbonate in dilute aqueous solutions: Ion-association and carbonate hydrolysis effects

Johannes Hunger, Roland Neueder, Richard Buchner, Alexander Apelblat

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21 Scopus citations

Abstract

We study the conductance of dilute aqueous solutions for a series of guandinium salts at 298.15 K. The experimental molar conductivities were analyzed within the framework of the Quint-Viallard theory in combination with Debye-Hückel activity coefficients. From this analysis, we find no evidence for significant ion association in aqueous solutions of guanidinium chloride (GdmCl) and guanidinium thiocyanate (GdmSCN), and the molar conductivity of these electrolytes can be modeled assuming a complete dissociation. The limiting ionic conductivity of the guanidinium ion (Gdm+) is accurately determined to λGdm+= 51.45 ± 0.10 S cm2 mol-1. For the bivalent salts guanidinium sulfate (Gdm 2SO4) and guanidinium carbonate (Gdm2CO 3), the molar conductivities show small deviations from ideal (fully dissociated electrolyte) behavior, which are related to weak ion association in solution. Furthermore, for solutions of Gdm2CO3, the hydrolysis of the carbonate anion leads to distinctively increased molar conductivities at high dilutions. The observed ion association is rather weak for all studied electrolytes and cannot explain the different protein denaturing activities of the studied guanidinium salts, as has been proposed previously.

Original languageEnglish
Pages (from-to)615-622
Number of pages8
JournalJournal of Physical Chemistry B
Volume117
Issue number2
DOIs
StatePublished - 17 Jan 2013

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