Reactions between plutonium ions

Keenan has made an investigation of the exchange reaction between Pu(IV) and Pu(in) in perchlorate media. The isotopic method was used with an a energy analyser to separate the tracer activity ( Pu) from that normally present from the major constituent ( Pu). Tributylphosphate extraction of the Pu(IV) formed the basis of the separation method. It was shown that the rate law has the approximate form 

5 M perchloric acid has a value 1.8x10 1.molesecat 0 °C. From results obtained at fi = 2.0 M, [H ] = 0.40 to 2.0 M, Keenan concluded that the pathways operative were 

Using known values of the constant K2, the values of and k2 were calculated as 1.8 X 10 and 1.3 x lO 1.mole . sec , respectively, at 0 °C and [i = 2.0 M. The activation energies and entropies obtained for the kj step were 7.7 kcal. mole and —31 cal.deg . mole for the k2 step values of 2.8 kcal.mole and —32 cal.deg . mole were found. 

Rabideau et al have used a spectrophotometric method [wavelengths, 600 m for (Pu(III) and 830 m for (Pu(VI) ] to investigate the reactions 

In acetic acid media in the presence of 0.5 M HCIO4, a modified reaction 

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Kasha, M. (1949) Reactions between plutonium ions in perchloric acid solution rates, mechanisms and equilibria, in... 

Balance the equation for the reaction between permanganate, MnO faqj, and plutonium(III), Pu+Yagj, to form manganous, Mn+2(ag), and plutonyl ion, PuO faq), in acid solution. 

The reactions to be expected between the radicals produced by the radiation of H2O with the plutonium ions in aqueous... 

The many possible oxidation states of the actinides up to americium make the chemistry of their compounds rather extensive and complicated. Taking plutonium as an example, it exhibits oxidation states of -E 3, -E 4, +5 and -E 6, four being the most stable oxidation state. These states are all known in solution, for example Pu" as Pu ", and Pu as PuOj. PuOl" is analogous to UO , which is the stable uranium ion in solution. Each oxidation state is characterised by a different colour, for example PuOj is pink, but change of oxidation state and disproportionation can occur very readily between the various states. The chemistry in solution is also complicated by the ease of complex formation. However, plutonium can also form compounds such as oxides, carbides, nitrides and anhydrous halides which do not involve reactions in solution. Hence for example, it forms a violet fluoride, PuFj. and a brown fluoride. Pup4 a monoxide, PuO (probably an interstitial compound), and a stable dioxide, PUO2. The dioxide was the first compound of an artificial element to be separated in a weighable amount and the first to be identified by X-ray diffraction methods. 

A fifth paper on this reaction seeks to clear up discrepancies between two sets of activation parameters reported for the k and k terms of this rate law. This paper also briefly discusses reactivities of 0x0- and hydroxo-bridged transition-metal complexes. Reactivities of these compounds can be compared with those for similar actinide species through kinetic results for decomposition of, for example, the [U020H]a + dimer, and the peroxo-bridged plutonium species [Pu—O2—PuOH] +. The rate of decomposition of this last complex is proportional to hydrogen ion concentration— there is just one acid-catalysed path here, in contrast to the parallel pH-dependent and pH-independent paths for the [Fe(OH)]a + dimer. 

Desire, Hussonnois and GuUlaumont (1969) determined stability constants for the species AnOH + for the actinides, plutonium(III), americium(III), curium (III), berkelium(III) and californium (III) using a solvent extraction technique. The stability constants obtained for americium(III) and curium(III) are two orders of magnitude larger than other similar data available in the literature. The stability constants of the lanthanide(III) and actinide(III) ions are very difficult to obtain using solvent extraction due to problems associated with attainment of maximum extraction into the solvent phase before the narrow band of pH between the onset of hydrolysis reactions and the precipitation of solid hydroxide phases. Consequently, the data of Desire, Hussonnois and GuUlaumont (1969) are not retained in this review. 

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