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The kinetics of Pu(IV) reduction with zinc amalgam under different conditions [HSO concentration 0.5-4.0 M, initial Pu(IV) concentration (1.11-4.80) × 10 M, temperature 294.0-323.0 K] was studied by spectrophotometry. The kinetic scheme of the Pu(IV) transformation and the rate law were suggested, and the reduction rate constants were determined. The activation energies E and the thermodynamic functions of formation of the activated complex (activation Gibbs energy Δ G, enthalpy Δ H, entropy Δ S) were determined. [ABSTRACT FROM AUTHOR]

The kinetics of reduction of U(VI) with zinc amalgam at HSO concentrations of 0.5-4.0 M, initial UO concentrations of (2.08-40.00) × 10 M, and temperatures of 295.0-325.0 K was studied by spectrophotometry. The kinetic scheme of the UO transformation, the rate law, and the reduction rate constants were determined. The activation energy E and the thermodynamic functions of formation of the activated complex (Gibbs energy Δ G, enthalpy Δ H, and entropy Δ S of activation) were calculated. [ABSTRACT FROM AUTHOR]

The kinetics of chemical reduction of Np(V) with iron(II) sulfamate in HNO solutions was studied by spectrophotometry. The reduction process can be described by the equation NpO + Fe + 4H ⇆ Np + Fe + 2HO and follows the first- and zero-order rate law with respect to the Np(V) concentration. The reaction rate constants were determined in relation to the HNO concentration (1-3 M), iron(II) sulfamate concentration [(0.59-2.94) × 10 M], and temperature (298.2-319.2 K). The activation energy ( E) and the thermodynamic functions of formation of the activated complex (activation free energy Δ G, enthalpy Δ H, entropy Δ S) were calculated. [ABSTRACT FROM AUTHOR]