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

A Discussion of selected references
415
[2001PER/KUN]
Molar heat capacities at constant pressure of six solid solutions and 11 intermediate
phases in the Pd-Pb, Pd-Sn and Pd-In systems were determined each 10 K by
differential scanning calorimetry from 310 to 1000 K. The experimental values have
been fitted by polynomials. Results are given, discussed and compared with available
literature data.
ο
This paper gives new C p,m results for 17 different alloys of palladium with
indium, tin or lead. The scarcity of data in literature does not allow a throughout
comparison and a crosscheck of our work. Our own investigations indicate that the most
probable uncertainty of our measurements is about 5% or 1 J·K –1·mol –1 . Further
investigations are necessary to extend the temperature range to higher temperatures and
to improve the accuracy of the data.
These data are not useful in the present context or in any context because they
do not meet the NEA requirements. The binary Pd-Sn system data was not targeted in
the current work on Sn review.
[2001SEB/POT]
In this review the accuracy of published thermodynamic data on inorganic tin
compounds was evaluated to obtain a reliable basis for modelling Sn migration in a
deep repository of radioactive waste. Hydrolysis, complexation with halide ions or other
inorganic compounds, and precipitation reactions of Sn(II) and Sn(IV) were studied.
The Guggenheim-Scatchard Specific Interaction Theory was used to correct equilibrium
constants to zero ionic strength. Tin(II) can be hydrolyzed into SnOH + , Sn(OH) 2 (aq)
and Sn(OH) −
2
3
at low concentration. For higher tin levels, the Sn
2(OH) +
2
and
2
Sn
3(OH) +
4
polynuclear species are predominant. Stability constants of these equilibria
at the standard state were evaluated from data available in the literature and
recommended values are proposed. Complexation reactions between tin(II) and halide
ions are well known, but the complex species formed are only present in solutions when
halide concentration is > 10 –3 mol dm –3 and at pH values < 4. In the presence of
sulphides, selenides, or tellurides, the tin(II) ions form very stable solid phases. Because
of the very low solubility of SnO 2 (s), little information is available in the literature
about Sn(IV) hydrolysis, complexation, or precipitation reactions.
[2001SOL/VLA]
The thermochemical cycle used for determination of enthalpy of SnF 2 (s) involved
several reactions including the one for SnO(s), which is found to be consistent with the
calorimetric data measured by Lavut et al. [1981LAV/TIM]. The value of the standard
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enthalpy of formation of SnF 2 (s) at 298.15 K: Δ fHm(SnF 2 , s, 298.15 K) =
− (695.2 ± 1.7) kJ·mol –1 has been accepted. This value differs vastly from the
CHEMICAL THERMODYNAMICS OF TIN, ISBN 978-92-64-99206-1, © OECD 2012