The ion product of H2O, dissociation constants of H2CO3 and Pitzer parameters in the system Na+/H+/OH-/HCO3(-)/CO3(2-)/ClO4(-)/H2O at 25 degrees C

The ion product of water and the dissociation constants of carbonic acid have been determined in 0.1, 1.0, 3.0, and 5.0M NaCIO4 at 25 degrees C. The ion product of water K'(w) has been evaluated by emf measurements with a combined glass electrode in NaClO4 solutions containing 0.001-0.1M HClO4 or NaOH. The product K'K-H'K-1'(2) of the Henry constant for CO2 and the dissociation constants for H2CO3 have been determined by titration of carbonate solutions equilibrated with pCO(2) = 10(-3.52) arm, and K'(2) has been evaluated by potentiometric titration and by measuring the HC concentration at fixed HCO3- and CO32- concentrations. The ion interaction (Fitter) equations are applied to describe the constants K'(w), K'(2) and K'K-H'K-1'(2) as a function of the NaClO4 concentration. The experimental data are used to evaluate the mixing parameters theta(i/ClO4)- and psi(i/ClO4)-(/Na+) for i = OH-, HCO3- and CO32-. Similar studies have been carried out in 5.0M NaCl. The results agree with the values calculated by the Fitter approach applying known ion interaction parameters in the system Na+/H+/OH-/HCO3-/CO32-/Cl-/H2O.