Thermodynamics of lutetium uranosilicate

The standard enthalpy of formation of crystalline Lu(HSiUO6)3 · 10H2O at 298.15 K, −10668.0±16.0 kJ mol−1, and the standard enthalpy of its dehydration were determined by reaction calorimetry. The heat capacity of this compound in the range 80–300 K was measured by adiabatic vacuum calorimetry, and its thermodynamic functions were calculated. The standard entropy of formation at 298.15 K is −3812.9±1.2 J mol−1 K−1, and the standard Gibbs energy of formation at 298.15 K, −9531.0±16.5 kJ mol−1. The standard thermodynamic functions of the reactions of the synthesis of lutetium uranosilicate were calculated and discussed.