Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

ABSTRACT

The enthalpy of formation at 298.15 K and low temperature heat capacity of Cs3Na(MoO4)2 have been measured for the first time in this work using solution calorimetry and thermal-relaxation calorimetry in the temperature range T = (1.9 299.6) K, respectively. The solution calorimetry measurements, performed in 2 M HNO3 solution, have yielded an enthalpy equal to DrHm(298.15 K) = (6.79 1.72) kJ mol 1 for the reaction: 3=2Cs2MoO4ocrP p 1=2Na2MoO4ocrP 1/4 Cs3NaoMoO4P 2 ocrP Combining with the enthalpies of formation of Cs2MoO4(cr) and Na2MoO4(cr), also determined in this work in 0.1 M CsOH and 0.1 M NaOH solutions, respectively, the standard enthalpy of formation of Cs3Na(MoO4)2 at 298.15 K has been determined as DfHo m(Cs3Na(MoO4)2, cr, 298.15 K) = (2998.5 3.0) kJ mol 1. The heat capacity and entropy values of Cs3Na(MoO4)2 at 298.15 K have been derived as Co p;m oCs3NaoMoO4P 2; cr; 298:15 KP 1/4 o296:3 3:3P J K 1 mol 1 and So m oCs3NaoMoO4P 2; cr; 298:15 KP 1/4 o467:2 6:8P J K 1 mol 1. Combining the newly determined thermodynamic functions, the Gibbs energy of formation of Cs3Na(MoO4)2 at 298.15 K has been derived as DfGo m oCs3NaoMoO4P 2; cr; 298:15KP 1/4 o2784:6 3:4P kJ mol 1. Finally, the enthalpies, entropies and Gibbs energies of formation of Cs3Na (MoO4)2 from its constituting binary and ternary oxides have been calculated.