Potentiometric investigation of the weak association of sodium and carbonate ions at 25°C

Capewell, S.G., Hefter, G. and May, P.M. (1998) Potentiometric investigation of the weak association of sodium and carbonate ions at 25°C. Journal of Solution Chemistry, 27 (10). pp. 865-877.

Abstract

The weak association between sodium and carbonate ions has been investigated at 25°C using high-precision sodium ion-selective electrode potentiometry in solutions of ionic strength ranging from 0.5 to 7.0 M in CsCl and in 1.0 M Me4NCl media. The protonation constants of CO2-3 (aq) were also measured, using a H+-responsive glass electrode in 1.0 M Me4NCl and NaCi. The value of the ion-pair association constant calculated from the difference in the protonation constants in these two media was in excellent agreement with that obtained from the Na+ISE measurements. Evidence is also presented for the formation of extremely weak ion pairs between Na+ and HCO-3 and between Cs+ and CO2-3.