HIGH-TEMPERATURE ENTHALPY INCREMENTS OF URANYL DIHALIDES UO2F2, UO2CL2, UO2BR2 (X=F,CL,BR), AND THERMODYNAMIC FUNCTIONS

The enthalpy increments of UO2F2, UO2Cl2, and UO2Br2 have been measured by means of a diphenyl ether drop calorimeter. For UO2F2 the results in the temperature range 298 to 811 K can be represented by the polynomial equation: {H°(T)-H°(298.15K)}/Jmol-1=123.554(T/K)+2.4404×10-3(T/K)2+21.729×5(T/K)-1-44343 In the range 298 to 649 K the enthalpy increments of UO2Cl2 can be represented by: {H°(T)-H°(298.15K)}/Jmol-1=115.275(T/K)+9.1116×10-3(T/K)2+11.418×5(T/K)-1-39009 Enthalpy increments for UO2Br2 can be represented, in the temperature range 298 to 454 K, by: {H°(T)-H°(298.15K)}/Jmol-1=104.270(T/K)+18.969×-3(T/K)2-32774 The thermodynamic functions of UO2F2 and UO2Cl2 have been calculated from 300 to 800 K. © 1979.