Temperature dependence of Th IV hydrolysis constants

The temperature dependence of Th(lV) hydrolysis constants has been investigated by Baes et al. [1965BAE/MEY] at 0, 25 and 95°C and Ekberg et al. [2000EKB/ALB] at 15, 25 and 35°C, both studies in 1 M NaC104. Baes et al. [1965BAE/MEY] used,  

A // (V11.28) calculated in these two studies are not consistent within the reported uncertainty ranges (Table Vll-14). The reported entropies of reaction are even 

The data for Th(OH)3 and Th(OH)4(aq) determined in [2000EKB/ALB] by liquid-liquid extraction are not accepted by this review (cf. Appendix A). 

For reasons of consistency, the equilibrium constants log,o at 25°C calculated with the log,o and values selected in the present review 

The temperature dependence of a , the activity of water, is known -RT (dlna IdT) = 0.033 kJ mol for 1.05 mNaClOq [1991PIT] (c/ Table IX.14 in [1997GRE/PLY2]). However, for the activity coefficients of the highly charged Th(IV) species only the temperature dependence of the Debye-Hiickel term can be calculated (Al= 4 R7 (5A, /5r)p = 1.986 kJ-kg -mof at 25°C [1991PIT]) the temperature 

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