Density, Electrical Conductivity, Acidity, Viscosity and Raman Spectra of Aqueous NaBO₂, Na₂B₄O₇ and NaB₅O₈ Solutions at 298.15 and 323.15K

Abstract

Density, electrical conductivity, viscosity and acidity of aqueous NaBO₂, Na₂B₄O₇ and NaB₅O₈ solutions were preciously measured as functions of concentration from dilute to super-saturation at 298.15 and 323.15 K. The results are in reasonable agreement with literature data where comparisons are possible. Semi-empirical equations for those properties vs concentration were also suggested. Coupling with Raman spectra of some concentrated samples, main species and possible equilibria were listed by elaborate deduction. In aqueous sodium borate solutions, at least five polyborate species i.e. B(OH)₃, B(OH)₄-, B₃O₃(OH)₄-, B₄O₅(OH)₄²- and B₅O₆(OH)₄- exist, and their distribution and relevant mechanism were also suggested.