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

386
A Discussion of selected references
Figure A-45: Heat capacity data for β-SnBr 4 .
144
142
140
1983BER/STE
β (I) (II) (III) exp. data
smoothed data
calc.: lin. reg., data at T > 296 K rejected
95% confidence limits
–1·mol
–1
C° p,m
/J·K
138
136
134
132
130
286 288 290 292 294 296 298 300 302 304
T / K
Table A-50: Thermodynamic quantities for phase transitions of SnBr 4 (cr).
Transition α → β β → liquid
T/K 287.0 ± 0.1 302.25 ± 0.05
o
Δ trsHm
/J·mol −1 1083 ± 3 1250 ± 30
Δ o
trs m 3.774 ± 0.010 40.20 ± 0.10
[1983TOP/KOC]
Precipitation and dissolution of SnS 2 was investigated in aqueous solutions of HCl and
CaCl 2 at 25 °C and 1 atm H 2 S. SnCl 4 is used as starting material. Approaching the
equilibrium by precipitation and dissolution shows that at high chloride concentration
(5 M) equilibration times of 2 to 3 months are required. Solid phases were identified by
X-ray analysis. Concentration of tin was determined by complexometric titration and
chloride content also volumetrically by the method of Volhardt. No polymorphic phase
alterations were observed during ripening of the solid in solution. Precipitation of SnS 2
is accompanied by formation of orthorhombic sulfur. The following table of solubility
data is given.
CHEMICAL THERMODYNAMICS OF TIN, ISBN 978-92-64-99206-1, © OECD 2012