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

A Discussion of selected references
267
Only Sn and Cl contents of the crystalline material were determined. In Table
A-3 the stoichiometrically required composition is given in parentheses. The analytical
results of the hexagonal rosets agree at least as good with Sn 21 Cl 16 (OH) 14 O 6 as with
3SnCl 2·5SnO·3H 2 O. Thus Carson probably synthesised the same tin(II) hydroxide
chloride phase as did von Schnering et al. [1981SCH/NES] who definitively described
its structure. Carson believed that a compound 2SnCl 2·7Sn(OH) 2 had been prepared,
which is the most basic tin(II) chloride. The analytical results agree approximately with
2SnCl 2·7SnO, but not with 2SnCl 2·7Sn(OH) 2, as Table A-3. The “most basic tin(II)
chloride” is rather a mixture than a compound.
Table A-3: Composition of tin(II) chloride hydroxide oxide [1919CAR].
Composition 3SnCl 2·5SnO·3H 2 O(s)
hexagonal rosets
2SnCl 2·7Sn(OH) 2
“most basic salt”
Sn 21 Cl 16 (OH) 14 O 6 (cr)
abhurite
w(Sn) 73.63 (73.25)% 80.10 (73.77)% 73.45%
w(Cl) 16.51 (16.41)% 10.58 (9.79)% 16.71%
w(O) (9.87)% - 9.43%
w(H) (0.47)% - 0.42%
w(O) + w(H) 9.86 (10.34)% 9.32 (16.44)% 9.85%
[1922BUR/PAR]
Tin(II) hydroxides were prepared by methods described by [1844SCH], [1882DIT2]
and other authors. Analyses were carried out on tin(II) hydroxide samples synthesised
by five different methods. These samples had essentially the same composition
favouring the formula 3SnO·2H 2 O.
[1925BRI2]
Tin(II) chloride solutions were titrated with sodium hydroxide and the precipitation was
studied using the hydrogen electrode. The composition varied from SnCl 1.33 (OH) 0.67 at
pH ≈ 1.9 to Sn 0.14 (OH) 1.86 at pH ≈ 7.
Tin(II) hydroxides are treated in a comparatively short subsection on pg. 2132
and 2133. No quantitative information e.g. concerning its solubilities is given.
[1925SMR]
This investigation of the electrodeposition of tin was undertaken to complete the table
of deposition potentials of metals at the dropping mercury cathode and to examine the
basic and acidic properties of “tin hydroxide”.
“Sn(OH) 2 (am)” Sn 2+ + 2 OH – , log10 K ,0 = − 27.85
s
CHEMICAL THERMODYNAMICS OF TIN, ISBN 978-92-64-99206-1, © OECD 2012