THE CHEMISTRY OF URANIUM. XIV. THE THERMAL STABILITY OF SOME ACTINOID NITRATES

The thermal decomposition of Cs2 U(NO3)6 has been investigated. The activation energy for the decomposition reaction was estimated to be ±120 kJ/mole, while the enthalpy of the reaction was calculated as 18 kJ/mole. These energy parameters were compared with similar parameters obtained for the decomposition of Cs2 Th(NO3)6 and U(NO3)4.2hmpa. It indicated that the nitrate ion is primarily responsible for the oxidation of the uranium with atmospheric oxygen having no effect at all. The dissociation reactions involved in the decomposition of M(NO3)4.4hmpa, (M = U and Th), are accompanied by intramolecular rearrangements of the nitrate groups.