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

114
VII Tin oxygen and hydrogen compounds and complexes
log
log
K (SnO 2 , cr, 298.15 K) = – (8.06 ± 0.11)
ο
10 s,0
K (SnO 2 , am, 298.15 K) = – (7.22 ± 0.08).
ο
10 s,0
Table VII-2: Experimental equilibrium data for the hydrolysis of tin(IV).
Method Ionic media t/°C log10
Sn(OH) 4 (aq) + 4 H + Sn 4+ + 4 H 2 O(l)
β Reference
Reported Recalculated (a) Accepted (b)
sp 1 M (H/K)NO 3 25 − 0.17 (c) [1971NAZ/ANT]
Sn(OH) 4 (aq) + 3 H + Sn(OH) 3+ + 3 H 2 O(l)
sp 1 M (H/K)NO 3 25 0.66 (c) [1971NAZ/ANT]
Sn(OH) 4 (aq) + 2 H + 2
Sn(OH) +
2 + 2 H 2 O(l)
sp 1 M (H/K)NO 3 25 1.04 (c) [1971NAZ/ANT]
Sn(OH) 4 (aq) + H + Sn(OH) +
3 + H 2 O(l)
sp 1 M (H/K)NO 3 25 0.97 (c) [1971NAZ/ANT]
Sn(OH) 4 (aq) + H 2 O(l) Sn(OH) −
5 + H +
sol → 0 (NaOH) 25 − 12.4 −11.28 ± 0.09 [1970BAR/KLI]
sol 0.1 M NaClO 4
→ 0
25 − 7.75
− 7.97
− 8.38 ± 0.25
− 8.60 ± 0.30
− 8.38 ± 0.30
− 8.60 ± 0.40
[1997AMA/CHI]
[1998ODA/AMA]
Sn(OH) 4 (aq) + 2 H 2 O(l) Sn(OH) 2−
6 + 2 H +
sol → 0 (NaOH) 200 − 20.2 (d) − 20.16 ± 0.20 (d) [1973KLI/BAR]
sol 0.1 M NaClO 4
→ 0
25 − 17.74
− 18.38
− 18.01 ± 0.11
− 18.67 ± 0.15
− 18.01 ± 0.20
− 18.67 ± 0.30
[1997AMA/CHI]
[1998ODA/AMA]
(a) Re-evaluated values, see Appendix A.
(b) Accepted values corrected to molal scale. The accepted values reported in Appendix A are expressed on
the molar or molal scales, depending on which quantities were used originally by the authors.
(c) Using pK w = 13.74 for I = 1 M KNO 3 .
(d) Using pK w = 11.2 for I = 0 and T = 200 °C.
p
ο
These values were selected and correspond to Δ (SnO 2 , am, 298.15 K) =
− (511.87 ± 0.78) kJ mol –1 fGm
ο
and Δ G (Sn(OH) 4 , aq, 298.15 K) = − (944.93 ± 0.66).
f
m
The dissolution of SnO 2 (s) above pH 8 was explained by the formation of
either Sn(OH) −
2
5 [1970BAR/KLI], or Sn(OH) −
6 [1973KLI/BAR], as well as by the
presence of both species [1970KUR/BAR], [1997AMA/CHI], [1998ODA/AMA]. The
hydrolysis constants reported in [1970KUR/BAR] for T = 373 K were later considered
as unreliable by the authors themselves [1973KLI/BAR], since the equilibration time
was too short to reach the equilibrium. The experimental methods applied in
[1997AMA/CHI] and [1998ODA/AMA] (radiometry using
113 Sn and ICP-MS
(inductively coupled plasma mass spectrometry)) allowed much higher precision than
CHEMICAL THERMODYNAMICS OF TIN, ISBN 978-92-64-99206-1, © OECD 2012