Enthalpies of formation of the monofluorolanthanide complexes

Effects of temperature and ionic strength on the stabilities of the first and second fluoride complexes of yttrium and the rare earth elements

“…7). The calorimetry results of Walker and Choppin (1967) (ϩ16 to ϩ40 kJ/mol) are much larger than our results and the results of Grant et al (1988). The value of ⌬H 1 for the formation of YF 2ϩ from Paul et al (1961) (ϩ9.92 kJ/mol) in 0.5 mol/L NaClO 4 and EuF 2ϩ from Baisden et al (1987) (ϩ9.61 Ϯ 0.03 kJ/mol) in 1.0 mol/L NaClO 4 are in good agreement with our result at I ϭ 0.025 mol/L and the results of Grant et al (1988) (see Fig.…”

“…The enthalpies for the formation of LnF 2ϩ from this study (⌬H 1 ϭ ϩ9.6 kJ/mol) are in good agreement with the titration calorimetry values of Grant et al (1988) in 1 mol/L NaClO 4 except for Pr and Nd (see Fig. 7).…”

“…Average values of ⌬H 1 ϭ ϩ9.6 Ϯ 0.4 kJ/mol and ⌬H 2 ϭ ϩ20.7 Ϯ 1.1 kJ/mol were found for the enthalpies. Our results are in reasonable agreement with literature values of ⌬H 1 (Paul et al, 1961;Baisden et al, 1987;Grant et al, 1988). The measurements from Byrne (2000, 2001) for the formation of LnF 2ϩ as a function of ionic strength in NaCl and NaClO 4 have been fitted to the Pitzer equations.…”

Comment on “An experimental study of the solubility and speciation of neodymium (III) fluoride in F-bearing aqueous solutions” by A.A. Migdisov and A.E. Williams-Jones

“…(1) to the data of Millero (2004) andWJ (2007). The results are in good agreement with enthalpy and entropy values of Grant et al (1988) and a number of others that are substantially lower than those of Walker and Choppin (1967) (Table 1) and were proven more reliable by Luo and Millero (2004). M&JW's comparison of their own findings with the upper curve in Fig.…”

“…1A, upper curve 28.6 ± 0.4 154 ± 5 Walker and Choppin (1967); 1 M NaClO 4 11.9 ± 1.8 115 ± 4 Fig. 1A, lower curve 13.5 ± 0.3 104 ± 5 Grant et al (1988); 1 M NaClO 4 9.38 ± 0.44 - Luo and Millero (2004) 5 times higher around T = 200°C than around T = 25°C.…”