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

A Discussion of selected references
259
A plot of [Sn(II)] tot vs. [OH − ] free can be interpreted by the following equilibria
leading to Eq. (A.3), see also Figure A-2:
Sn(OH) 2 (s) + OH − Sn(OH) 3
−
Sn(OH) 2 (s) + 2 OH −
2
Sn(OH) −
4
[Sn(II)] tot = K s,3 [OH − ] + K s,4 [OH − ] 2
where log 10 K s,3 = − (0.86 ± 0.04) and log 10 (K s,4 /dm 3·mol −1 ) = − (1.73 ± 0.10).
(A.1)
(A.2)
(A.3)
Figure A-2: Solubility of “Sn(OH) 2 (s)” in NaOH solutions.
0.8
Model: Sn(OH) 2
(s) + OH – Sn(OH) 3
–
Sn(OH) 2
(s) + 2OH – Sn(OH) 4
–
c[Sn(II) tot
]/mol·dm –3
0.6
0.4
0.2
K s,3
= (0.13762 ± 0.01353)
K s,4
= (0.01842 ± 0.00414)
log 10
K s, 3
= - (0.861 ± 0.043)
log 10
K s, 4
= - (1.735 ± 0.098)
exp. data [1906RUB]
c[Sn(II) tot
] = K s,3
c(OH – ) + K s, 4
c 2 (OH – )
χ 2 / DoF = 0.00051, R 2 = 0.99437
0.0
0 1 2 3 4
c(OH – )/mol·dm –3
Although the methodology of [1902RUB] has deficiencies log 10 K s,3 agrees
within the experimental uncertainty with the value derived from Garret and Heiks’ work
2
[1941GAR/HEI]. In addition [1902RUB] indicates formation of Sn(OH) −
4
or
2
SnO(OH) − 2
, a species not mentioned by previous reviews on tin species
[1976BAE/MES], [2001SEB/POT], [2002HUM/BER].
[1906GOL/ECK]
In this work the reduction of nitroanilines, nitrophenols, nitrobenzoic acids,
nitrobenzenesulfonic acids, and nitrobenzaldehydes was investigated. In the
introductory part the solubility of “tin hydroxide” in H 2 O and dilute solutions of NaOH
was also described. The experimental data were explained by two equilibria:
CHEMICAL THERMODYNAMICS OF TIN, ISBN 978-92-64-99206-1, © OECD 2012