Mean spherical approximation-mass action law theory of equilibrium and conductance in ionic solutions

An improved Bjerrum theory obtained by combining the mean spherical approximation with the mass action law (MSA&MAL) is used to calculate the fraction of ions unpaired over the full range of states of a primitive model electrolyte. It is combined with a new theory for the electrical conductance of the primitive model under the MSA to yield the conductance of an electrolyte over a wide range of concentrations and Bjerrum parameters with only two parameters A_o and R, the distance of closest approach, adjusted to fit the conductivity data. The theory fits the data for aqueous alkali halides over a wide concentration range with A_o values in good agreement with those deduced by more conventional theories and with reasonable small ion pairing constants deduced from the data. It fits the data for LiBr in octanol without the need for invoking triple ion formation. It leads to reasonable predictions for the conductance curves for 1:1 electrolytes even up to the molar region for solvents with dielectric constant from 10 to 80.