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

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VIII Group 17 (halogen) compounds and complexes
VIII.2.4 Solubility of tin iodides
VIII.2.4.1 SnI 2 (s)
Young [1897YOU] determined solubilities in the system SnI 2 -HI-H 2 O in a temperature
range from 273 to 373 K. At constant temperature, the solubility of SnI 2 decreases first
by addition of HI up to about w(HI) ≈ 0.1. With further addition of HI, it increases
strongly.
Figure VIII-13: Solubility in the system SnI 2 -HI-H 2 O as a function of temperature and
for different hydroiodic acid concentrations according to [1897YOU]. Experimental
data: : pure water; : w(HI) = 5.83%; : w(HI) = 9.50%; : w(HI) = 10.60%; :
w(HI) = 15.20%; : w(HI) = 20.44%.
6
5
100 w(SnI 2
)
4
3
2
1
0
10 20 30 40 50 60 70 80 90 100 110
(T – 273) / K
Combining the recommended formation enthalpy and entropy data of SnI 2 (cr) a
ο
Gibbs energy of formation of Δ fGm(SnI 2 , cr, 298.15 K) = − 160.528 kJ·mol –1 is
derived. With an ε(H + ,I – ) = 0.195 obtained from a SIT treatment of activity data in the
system HI-H 2 O at 25 °C [1959ROB/STO] and including the complex formation
constants [SnI q ] 2−q for q =1 to 4 (see Section VIII.3.4.1) the solubility of tin(II) iodide
can be calculated as a function of HI concentration. Figure VIII-15 shows the
comparison with experimental data [1897YOU]. Good agreement gives evidence that
the formation data derived from thermochemical measurements in the anhydrous system
are consistent with aqueous solubility data.
CHEMICAL THERMODYNAMICS OF TIN, ISBN 978-92-64-99206-1, © OECD 2012