Oxidations by neptunium

The reaction between Np(Vl) and V(III) in perchlorate media proceeds via consecutive steps of comparable rate, viz. 

Np020H +V. The activation energies and entropies of the k and k routes are, respectively, 32 kcal.mole and 52 16 cal.deg Lmole S and 13 kcal. mole and —9 6 cal.deg. mole (as recalculated by Newton and Baker Np(VI) oxidises U(IV) in a two-equivalent process 

In aqueous perchloric acid the rate law found by Sullivan et is 

Assuming a steady-state concentration for U(V), k is identified as K ki. The parameters describing the net activation process 

However, at acid concentrations less than 0.5 M, Np is formed by 

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