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

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A Discussion of selected references
Sn 21 Cl 16 (OH) 14 O 6 , which is the at present accepted formula of basic tin(II) chloride,
abhurite.
[1963HEF]
The author summarised properties of SnF 2 from literature. A solubility plot from “Tech.
Data Sheet No. 142 , M & T Chemicals, Inc., March 1961.
The temperature dependence of the solubility is described as to be linear.
Plots are given for the effect of aging of 0.4% SnF 2 solutions at different pH
from 3.0 to 4.5. The concentration of Sn 2+ decreases to 90% of the initial concentration
at pH = 3.0 during the first 20 days and remains constant until 100 days, the maximum
time of observation. At pH = 4.5 the decrease of Sn 2+ concentration reaches 50% after
100 days and is still further decreasing. Solutions of SnF 2 are more stable than those of
SnCl 2 .
[1964DON/DON]
The authors prepared the solid compounds: MSnF 3 and MSn 2 F 5 with M = NH 4 , Na, K
by adding the fluoride MF to a solution fo SnF 2 . Compounds were analyzed for tin(II),
total tin and fluoride. At least at 60 °C the trifluorostannates dissolve incongruently
under crystallisation of the Sn2F −
5 salt. Solubility data are given in g/100 mL solution
without densities. The compound MSnF 3 is obviously much more soluble than MSn 2 F 5 .
The analytical error in solubility determination given by the authors is 1% absolute. The
authors preformed potentiometric measurements, too, and reported the existence of a
dinuclear Sn2F − 5 ion when concentrated aqueous solutions of SnF 2 ([Sn 2+ ] > 0.3 M)
were titrated by MF solutions.
X-ray powder diffraction data for these compounds are reported and unit cell
paramaters were determined from the compounds.
Table A-19: Solubility of the compounds MSnF 3 and MSn 2 F 5 (M = NH 4 , Na, K) in H 2 O
and 0.1 M HF at different temperatures.
Pure water
Solubility/(g/100 mL solution)
1 M HF
25 °C 40 °C 60 °C 25 °C 40 °C 60 °C
NH 4 SnF 3 59 74 78 59 65 79
NH 4 Sn 2 F 5 4.4 6.4 10.6 8.6 9.3 10.5
Na \ SnF 3 9.6 26.6 Incongr. 13.5 15.2 Incongr.
NaSn 2 F 5 5.6 8.4 11.7 6.0 8.1 10.4
KSnF 3 9.1 13.7 Incongr. 11.4 12.8 Incongr.
KSn 2 F 5 2.5 6.8 12.3 5.1 6.9 9.9
CHEMICAL THERMODYNAMICS OF TIN, ISBN 978-92-64-99206-1, © OECD 2012