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chemical thermodynamics of neptunium and plutonium - U.S. ...

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158 9. Neptunium group 17 (halogen) compounds <strong>and</strong> complexesTable 9.3: Experimental equilibrium data for the <strong>neptunium</strong>(IV) fluoride system.Method Ionic t log ∗ 10 β q(a)medium ( ◦ C)Np 4+ + HF(aq) Å NpF 3+ + H +log 10 ∗ β ◦ (a)qReferencecix 4 M HClO 4 20 (4.82 ± 0.02) [66AHR/BRA]4MHClO 4 25 (4.79 ± 0.10) (b,c)cix 2 M HClO 4 25 (4.70 ± 0.30) (b) [69KRY/KOM]1MHClO 4 25 (4.56 ± 0.30) (b)cix 2 M HNO 3 25 (4.75±0.30) (b,d) [69KRY/KOM3]1 M HNO 3 25 (4.74±0.30) (b,d)dis-HD 2 M HClO 4 25 (4.62 ± 0.20) (b) [75PAT/RAM]dis-HTTA 2 M HClO 4 25 (4.60 ± 0.20) (b)dis-HTTA 2 M HClO 4 25 (4.70 ± 0.15) (b) [76BAG/RAM]dis 1 M HClO 4 10 4.71 [76CHO/UNR]1MHClO 4 25 (4.60 ± 0.20) (b)1MHClO 4 40 4.52ise-F − 1M 23 5.21 (c,e) [90SAW/CHA2](H,Na)ClO 4Np 4+ + 2HF(aq) Å NpF 2+2+ 2H +cix 4 M HClO 4 20 (7.57 ± 0.15) (b) (9.30±0.75) [66AHR/BRA]red 4 M HClO 4 20 (7.51 ± 0.15) (b,f) (9.24±0.75)dis-HTTA 2 M HClO 4 25 (7.49 ± 0.40) (b) (9.44±0.52) [75PAT/RAM]dis-HTTA 2 M HClO 4 25 (7.38 ± 0.30) (b) (9.32±0.45) [76BAG/RAM]ise-F − 1M 23 8.62 (e) 10.49 [90SAW/CHA2](H,Na)ClO 4Np 4+ + 3HF(aq) Å NpF + 3 + 3H+red 4 M HClO 4 20 9.85 (f) 11.8 [66AHR/BRA]ise-F − 1MHClO 4 23 11.20 (e) 13.4 [90SAW/CHA2]Np 4+ + 4HF(aq) Å NpF 4 (aq) + 4H +red 4 M HClO 4 20 ∼ 11.15 (f) 13.3 [66AHR/BRA]ise-F − 1MHClO 4 23 14.15 (e) 16.4 [90SAW/CHA2](a) Refers to the reactions indicated, the ionic strength <strong>and</strong> temperature given in the table. log ∗ 10 βq◦is in molal units, at I = 0 <strong>and</strong> 298.15 K.(b) Uncertainty estimated in this review (cf. Appendix A).(c) Corrected to 25 ◦ C using the reaction enthalpy selected in this review.(d) Corrected for the formation <strong>of</strong> NpNO 3+3(cf. Appendix A).(e) The published values refer to Reactions (9.5) <strong>and</strong> have been converted to conform to the reactions<strong>of</strong> this table (cf. Appendix A).(f) Reported as stepwise constants:log 10 ∗ K 2 = (2.69 ± 0.10), log 10 ∗ K 3 = (2.34 ± 0.15), <strong>and</strong>log 10 ∗ K 4 ≈ 1.3. They are converted to overall formation constants by using log 10 ∗ K 1 = 4.82from the ion exchange experiments [66AHR/BRA] (see Appendix A).

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