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

126
VII Tin oxygen and hydrogen compounds and complexes
Figure VII-10: Solubility of SnO(cr) in NaOH solutions (: experimental data
[1941GAR/HEI]; solid line: linear fit; dashed lines: confidence limits; dotted lines:
prediction limits).
-0.70
-0.75
-0.80
log 10
{ * K s3
/a(H 2
O)}
-0.85
-0.90
-0.95
-1.00
-1.05
-1.10
-1.15
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
m(Na + )/mol·kg –1
A still older study on the solubility of “Sn(OH) 2 ”(s) in sodium hydroxide
solutions [1902RUB], where information concerning the equilibration temperature
is lacking, resulted in a similar value of log K = − (0.86 ± 0.04).
* ο
10 s3
ο
With the NEA auxiliary data for (OH – ο
ΔfGm
, 298.15 K), ΔfGm
(H 2 O, l,
ο
298.15 K) and Δ G (SnO, cr, 298.15 K) selected by this review team,
f
f
m
Δ G ( Sn(OH) − , 298.15 K) = − (645.01 ± 0.77) kJ·mol –1
ο
m
is obtained and has been selected, see Section VII.1.1.
VII.2.2.4
Selected data
3
The thermodynamic data from previous critical evaluations are summarised in
Table VII-4.
The choice of the value of enthalpy of formation of SnO(cr) is difficult based
on the data listed above and must be made on the basis of additional constraints as
reviewed in Section VII.2.2.3. As discussed in Appendix A, the critique of Humphrey
and O'Brien [1953HUM/OBR] data by Lavut et al. [1981LAV/TIM] is not totally
justified. Since the solubility data discussed in Section VII.2.2.3 favour the lower value
CHEMICAL THERMODYNAMICS OF TIN, ISBN 978-92-64-99206-1, © OECD 2012