Study of some thermodynamic properties of 5f elements

Tabulations were recently published on the enthalpy of sublimation for the 4f and 5f metals at 298.15K, ΔH/sub S/0(M), and the standard enthalpy of formation at 298.15K, ΔH/sub f/0 (M/sub aq/3+), for the tripositive aqueous metal ions for these two series. Values in this tabulation for the latter half of the 5f series were not obtained from experimental measurements, but from theoretical consideration and empirical correlations drawn from the trends in the 4f series. In the present work new experimental data were used for the 5f series to modify the empirical correlations, and tabulate new values for ΔH/sub f/0 (M/sub aq/3+) and ΔH/sub S/0(M) for the second half of the 5f series. In addition, values for ΔG/sub f/0 (M/sub aq/3+) [ΔG/sub f/0 = -3FE0 (M/sub aq/3+/M) = ΔH/sub f/0 - TΔS/sub f/0 for the reaction M + 3H/sub aq/+ M/sub aq/3+ + 3/2 H2] are given for the 5f series and the oxidation-reduction properties of the 5f elements are discussed. (U.S.)