Thermochemistry of hydrated lithium monoborates

Abstract The enthalpies of solution of two hydrated lithium monoborates in approximately 1 mol dm −3 aqueous hydrochloric acid were determined. From these results and the enthalpies of solution of H 3 BO 3 in approximately 1 mol dm −3 HCl(aq), and of LiCl·H 2 O in aqueous(hydrochloric acid + boric acid),combining with the standard molar enthalpies of formation of LiCl·H 2 O(s), H 3 BO 3 (s) and H 2 O(l), the standard molar enthalpies of formation of −1627.46±0.90 and −3397.00±0.94 kJ mol −1 for LiBO 2 ·2H 2 O and LiBO 2 ·8H 2 O were obtained. The standard molar entropies of formation of LiBO 2 ·2H 2 O and LiBO 2 ·8H 2 O were calculated from the thermodynamic relation with the standard molar Gibbs free energy of formation of LiBO 2 ·2H 2 O and LiBO 2 ·8H 2 O computed from a group contribution method.