Enthalpies and heat capacities of Li 2SiO 3 and Li 2ZrO 3 between 298 and 1400 K by drop calorimetry

Abstract

The enthalpies of Li 2SiO 3 and Li 2ZrO 3 were measured between 368 and 1414 K by an isoperibol Setaram HTC 1800 drop calorimeter. The calibration procedure is described. The smoothed enthalpies between 298 and 1400 K are: H° T - H° 298 <Li 2SiO 3 > = − 51157 + 125.860 T + 0.01713 T 2 + 3614467 T −1 J/mol H° T - H° 298<Li 2ZrO 3 > = −46453 + 134.857 T + 0.00740 T 2 + 1671251 T −1 J/mol The standard deviation is ≈ 3%. The heat capacities were derived by differentiation. The values extrapolated to 298 K are: C p,298 <Li 2SiO 3 > = (95.4 ± 3.1)J/K mol C p,298 <Li 2ZrO 3 > = (120.4 ± 3.0)J/K mol