Standard molar enthalpy of formation of lithium molybdates (Li 2Mo nO 3 n+1 with n = 1, 2, 3 and 4) at 298.15 K

Abstract

Four compounds in the system Li 2O-MoO 3, namely, Li 2MoO 4(c), Li 2Mo 2O 7(c), Li 2Mo 3O 10(c) and Li 2Mo 4O 13(c) were synthesized and characterized by both chemical and X-ray diffraction analyses and confirmed to be single-phase compounds. The molar enthalpies of solution of these compounds have been measured at 298.15 K using an isoperibol calorimeter and the respective values at infinite dilution, Δ sol H m α (298.15 K), for the compounds Li 2MoO 4(c), Li 2Mo 2O 7(c), Li 2Mo 3O 10(c) and Li 2Mo 4O 13(c) are −(33.88 ± 0.51), −(97.68 ± 0.52), −(167.20 ± 0.30) and −(247.68 ± 0.88) kJ mol −1 respectively. These data were used to calculate the standard molar enthalpies of formation Δ f H m o (298.15 K) and the respective values for the compounds are −(1520.13 ± 0.94), −(2279.29 ± 1.76), −(3032.68 ± 2.53) and −(3775.26 ± 3.46) kJ mol −1. The results are compared with the available data in the literature.