Free energy of formation of Cs3PuCl6 and CsPu2Cl7

The free energy, enthalpy and entropy of formation of the compounds Cs3PuCl6 and CsPu2Cl7 have been determined by measuring the sublimation pressures for the reactions: CsCl(s) = CsCl(g), 2/5 Cs3PuCl6(s) = 1/5 CsPu2Cl7(s) + CsCl(g), and CsPu2Cl7(s) = 2 PuCl3(s) + CsCl(g). The pressures are measured using Knudsen effusion mass spectrometry over the temperature range 600 to 850 K. For the formation of Cs3PuCl6 from CsCl and PuCl3, ΔG2980 = -77.3 +/- 8.5 kJ/mole, ΔH2980 = -82.1 +/- 7.8 kJ mole, and ΔS2980 = -16.2 +/- 10.9 J/K mole. For CsPu2Cl7, ΔG2980 = -39.4 +/- 3.5 kJ/mole, ΔH2980 = -40.8 +/- 3.2 kJ/mole, and ΔS2980 = -4.6 +/- 4.2 J/K mole