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

188
VIII Group 17 (halogen) compounds and complexes
Figure VIII-28: Extrapolation to I = 0 of the experimental data for reaction Sn 2+ +
3 Br – SnBr −
3
in NaClO 4 media. Experimental data from [1928PRY], [1952VAN],
and [1969FED/BOL].
5
4
Sn 2+ + 3Br – SnBr – 3
log 10
β 3
+ 6D
3
2
1
0 2 4 6 8
I / mol·kg –1
The corresponding ion interaction coefficients are Δε((VIII.13), q = 2) =
− (0.16 ± 0.05) kg·mol –1 and Δε((VIII.13), q = 3) = − (0.18 ± 0.06) kg·mol –1 ,
respectively. From these values ε(SnBr 2 (aq), NaClO 4 (aq)) = (0.14 ± 0.07) kg·mol –1 and
ε(Na + , SnBr − 3
) = (0.16 ± 0.08) kg·mol –1 can be derived. As described in Appendix B,
interaction coefficients for neutral species like ε(SnBr 2 (aq),NaClO 4 (aq)) are expected to
be generally small, but when data make possible to determine them as in the current
case, the value has to be reported.
and hence
The selected thermodynamic formation constants correspond to
ο
rGm
ο
rGm
ο
rGm
Δ ((VIII.13), q = 1, 298.15 K) = – (7.6 ± 1.0) kJ·mol –1 ,
Δ ((VIII.13), q = 2, 298.15 K) = – (11.2 ± 1.2) kJ·mol –1 ,
Δ ((VIII.13), q = 3, 298.15 K) = – (11.0 ± 1.5) kJ·mol –1 ,
ο
fGm
ο
fGm
ο
fGm
Δ (SnBr + , aq, 298.15 K) = − (138.8 ± 1.1) kJ·mol –1 ,
Δ (SnBr 2 , aq, 298.15 K) = − (246.3 ± 1.3) kJ·mol –1 ,
Δ ( SnBr − 3
, aq, 298.15 K) = − (350.0 ± 1.6) kJ·mol –1 .
CHEMICAL THERMODYNAMICS OF TIN, ISBN 978-92-64-99206-1, © OECD 2012