Mobilities and ion-pairing in LiB(OH)4 and NaB(OH)4 aqueous solutions. A conductivity study

The conductivities of aqueous solutions of sodium borate at 25°C and lithium borate at various temperatures are reported. The conductivity of the B(OH) ₄ ⁻ ion is 35.3 ±0.2 S-cm²-mole⁻¹ at 25°C. The electrolytes are both associated, the lithium salt being more associated than the sodium salt. The mobilities and association constants obtained from the conductivity data agree with a model recently proposed for the H₂O−B(OH) ₄ ⁻ interactions. A discrepancy in the reported thermodynamic behavior of NaB(OH)₄ aqueous solutions has been resolved by means of the association constants obtained in the present study. Thus the usefulness of the conductivity measurements to determine excess chemical potentials of binary electrolytes in dilute solution is again shown.