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

A Discussion of selected references
369
Table A-43: Molality basis at 25 °C [1979VAS/GLA].
c − −
(ClO4
+ Cl ) /
M
m +
H / m 4+ Sn /
mol·kg –1 mol·kg –1
m + /
2
Sn I/
mol·kg –1
m − −
(ClO4
+ Cl ) / E/
mol·kg –1 mol·kg –1 V
E + k⋅ D /
o
(
m
' 5 )
V
2.088 2.225 0.002975 0.013308 2.341 2.310 0.16340 0.27310
2.092 2.232 0.004815 0.006776 2.368 2.315 0.17760 0.27265
2.099 2.237 0.005712 0.005295 2.384 2.323 0.18309 0.27291
2.097 2.231 0.004413 0.009200 2.370 2.321 0.17190 0.27200
3.082 3.497 0.003979 0.012252 3.616 3.583 0.15194 0.27287
3.064 3.498 0.006485 0.013320 3.644 3.558 0.15720 0.27301
3.083 3.494 0.003235 0.015147 3.608 3.584 0.14650 0.27277
3.036 3.486 0.003275 0.014833 3.607 3.521 0.14710 0.27288
3.082 3.503 0.007533 0.003026 3.652 3.582 0.17800 0.27291
4.112 4.925 0.013626 0.001914 5.137 5.039 0.17880 0.27211
4.165 5.002 0.014094 0.001664 5.187 5.118 0.17990 0.27146
4.113 4.925 0.013921 0.001651 5.140 5.040 0.17960 0.27074
4.061 4.925 0.001822 0.013896 4.994 4.964 0.12771 0.27208
4.074 4.906 0.007692 0.005225 5.035 4.983 0.15810 0.27138
[1980AND/SAM]
Potentiometric measurements using a capillary tin amalgam electrode have been
performed to study the complex formation processes between tin(II) and nitrate ion
under nitrogen atmosphere at 25 °C in (Na,H)ClO 4 medium at six different ionic
strengths (I = 1, 2, 3, 4, 6 and 8 M) by measuring the potential of the following cell:
Hg⏐HgCl 2 (s)⏐0.1 M NaCl, 0.5 M HClO 4 , I–0.6 M NaClO 4 0.5 M HClO 4 , I–0.5 M
NaClO 4 I–0.5–x M NaClO 4 , 0.5 M HClO 4 , x M NaNO 3 , 0.001 M Sn(ClO 4 ) 2 ⏐tin
amalgam.
The diffusion potential of the above cell was estimated in a separate
measurement, using NaI instead of Sn(ClO 4 ) 2 . Primary experimental data are reported
only for I = 3 M. Since the original (Na,H)ClO 4 background electrolyte was almost
entirely replaced by NaNO 3 during the measurements, resulting in a substantial change
of the activity coefficients, the raw data were re-evaluated for the purposes of this
review, using the data points corresponding to [ NO − 3
] tot ≤ 0.6 M (maximum 20%
replacement of the background electrolyte). At I = 3 M, the authors reported the
formation of three complexes ( SnNO + 3
, Sn(NO 3 ) 2 (aq), Sn(NO
3) − 3). Using the above
mentioned limited data set, the experimental data can be well reproduced considering
the formation of SnNO + 3
, Sn(NO 3 ) 2 (aq) (see Figure A-42). Therefore, the formation of
the tris-nitrato complex, reported in [1980AND/SAM] is ambiguous, since the
differentiation between the complex formation and medium effect is almost impossible
CHEMICAL THERMODYNAMICS OF TIN, ISBN 978-92-64-99206-1, © OECD 2012