Cryoscopy of polyborate ions in dilute solution in alkali halides

Abstract

Borates in the composition range tetraborate to orthoborate have been studied in dilute solution in potassium fluoride, chloride and bromide, and also in some alkali halide mixtures. It is concluded that in systems approaching the ortho composition, discrete ortho-ions predominate, whilst at compositions higher in B₂O₃ than ortho-, the system adopts a spectrum of ionic sizes including the monomer, BO^–₂. In the tetra- or di-borate region, solutions in chloride or bromide contain large ionic groups, but solutions in the fluoride contain small groups of boron-fluorine-oxygen ions.