Chemical Thermodynamics of Tin - Volume 12 - OECD Nuclear ...

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VII Tin oxygen and hydrogen compounds and complexes
Figure VII-5: Solubility of crystalline and amorphous SnO 2 as the function of pH in
0.1 M NaClO 4 solution, based on the experimental data reported in [1997AMA/CHI]
and [1998ODA/AMA] (: selected experimental data for SnO 2 (am); : selected
experimental data for SnO 2 (cr) [1997AMA/CHI]; : oversaturation experiments
[1998ODA/AMA]; : undersaturation experiments; solid line: obtained for SnO 2 (am)
*
using the re-evaluated values log10 K s,0
= − (7.22 ± 0.08), log10 β 5,1 = − (8.38 ± 0.25)
*
and log10 β 6,1 = − (18.01 ± 0.11) (see Appendix A); dashed line: obtained for SnO 2 (cr)
using the re-evaluated value log K = − (8.06 ± 0.11)).
10 s,0
-1
-2
log 10
([Sn(IV)] tot
/mol·kg –1 )
-3
-4
-5
-6
-7
-8
2 4 6 8 10 12
pH
VII.1.3 Mixed hydroxido complexes of tin(II)
*
The log10 β 1,1 values obtained in NaCl media [1981PET/MIL], [1995DJU/JEL] are
considerably higher than those determined in NaNO 3 or NaClO 4 solutions (see
Table VII-1). The difference is probably related to the formation of Sn(OH)Cl(aq).
Sn 2+ + H 2 O(l) + Cl – Sn(OH)Cl(aq) + H +
*
β 1,1,Cl
(VII.10)
The value of * β 1,1,Cl is related to * β 1,1 determined in NaCl and in
non-coordinating background electrolytes (NaClO 4 /NaNO 3 ):
*
β 1,1 (NaCl) ≈ * 1,1
*
β 1,1,Cl
β (NaClO 4 /NaNO 3 ) + .
Using the above relationship, log10 β1,1,Cl
≈ – 3.2 (0.5 M NaCl) and ≈ – 2.2
(3 M NaCl) can be derived from the data of [1981PET/MIL] and [1995DJU/JEL],
respectively. However, the high uncertainty of the constants reported in [1995DJU/JEL]
*
CHEMICAL THERMODYNAMICS OF TIN, ISBN 978-92-64-99206-1, © OECD 2012