Synthesis and thermodynamic functions of rubidium and caesium tetrachloroborates

Abstract

Pure rubidium and caesium tetrachloroborates have been prepared by a modification of an established method. Their standard heats of formation at 298·15 K are –220·7 ± 0·4 and –225·0 ± 0·3 kcal mol^–1 respectively as obtained from a thermochemical study of their hydrolyses. Dissociation pressures of caesium tetrachloroborate have been determined over the range 55–80 °C, from which the equilibrium constant for the dissociation at 25 °C has been estimated as 8 × 10^–5.