A Conductance Study of Guanidinium Chloride, Thiocyanate, Sulfate, and Carbonate in Dilute Aqueous Solutions: Ion-Association and Carbonate Hydrolysis Effects

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–Huckel 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 (Gdm2SO4) and guanidinium carbonate (Gdm2CO3), 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...