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

112
VII Tin oxygen and hydrogen compounds and complexes
and Δε((VII.6), NaOH) = (0.18 ± 0.03) kg·mol –1 .
* ο
10 3
* ο
Using the value of log K , the above selected log10
β
2,1
((VII.4), 298.15 K)
ο
* ο
and pK
w
= 14.00, log10 β
3, 1
= − (17.22 ± 0.40) can be derived.
The SIT analysis of the latter value and those reported in [1977MAR],
[1977SMI/KRA] and [1978DIC/LOT] resulted in the selected constant (Figure VII-4)
* ο
log10 β
3,1
((VII.5), 298.15 K) = − (17.00 ± 0.60).
Figure VII-4: Extrapolation of the equilibrium constants for reaction Sn 2+ +
3 H 2 O(l) Sn (OH) −
3
+ 3 H + determined in NaClO 4 media (solid squares). The data for
NaNO 3 media, recalculated from [1981PET/MIL] (open squares) were not included in
the regression.
-16
Sn 2+ + 3H 2
O Sn(OH) – 3 + 3H+
log 10
*
β13 – log 10
a w
-17
-18
-19
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
I / mol·kg –1
The calculated uncertainty (± 0.24) was increased to cover the value
extrapolated to I = 0 using the re-evaluated equilibrium constants from [1981PET/MIL]
* ο
( log10 β
3,1
= − (17.56 ± 0.40). From the slope of the straight line in Figure VII-4
Δε((VII.5), NaClO 4 ) = (0.21 ± 0.08) kg·mol –1 can be calculated, which corresponds to
ε(Na + , Sn(OH) − 3 ) = − (0.01 ± 0.10) kg·mol –1 . This ion interaction coefficient can also be
obtained from Δε((VII.6), NaOH) (see above). The calculation based on the data of
[1941GAR/HEI] results in ε(Na + , Sn(OH) − 3 ) = (0.22 ± 0.03) kg·mol –1 , which seems to
be more reliable than the above value.
CHEMICAL THERMODYNAMICS OF TIN, ISBN 978-92-64-99206-1, © OECD 2012