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

430
A Discussion of selected references
Table A-78: The formation constants used for the evaluation at different ionic strength
and the calculated standard potentials.
I m (I c ) Applied formation constants
2−n
(molar values) for SnCl
4.73
(3 M HclO 4
+ 1 M HCl)
6.22
(4 M HclO 4
+ 1 M HCl)
7.88
(5 M HclO 4
+ 1 M HCl)
log10 β
1
= 1.26, log10 β
2
= 1.98,
log10 β
3
= 1.97, log10 β
4
= 2.46,
log10 β
1
= 1.47, log10 β
2
= 2.36,
log10 β
3
= 2.35, log10 β
4
= 2.88,
log10 β
1
= 1.74, log10 β
2
= 2.83,
log10 β
3
= 2.84, log10 β
4
= 3.41,
n
Applied formation constants
4−n
(molar values) for SnCl
log10 β
1
= 2.43, log10 β
2
= 4.59,
log10 β
4
= 7.69, log10 β
5
= 8.91,
log10 β
6
= 8.74,
log10 β
1
= 2.78, log10 β
2
= 5.18,
log10 β
4
= 8.56, log10 β
5
= 9.73,
log10 β
6
= 9.71,
log10 β
1
= 3.22, log10 β
2
= 5.94,
log10 β
4
= 9.67, log10 β
5
= 10.79,
log10 β
6
= 10.94,
n
E
ο ' (Sn 4+ /Sn 2+ )/V
0.2797 ± 0.0123
0.2732 ± 0.0066
0.2627 ± 0.0087
Figure A-51: The observed E values of cell III as a function of log 10 ([Sn 4+ free]/[Sn 2+ free])
at I m = 4.73 (A), 6.22 (B) and 7.88 (C) (see also Table A-78).
0.14
0.13
A
exp. data, error bars: ± 0.005 V
linear fit, fixed slope:
k/2 = 0.02958 V / decade
E° = (0.2797 ± 0.0123) V
0.12
E / V
0.11
0.10
0.09
298.15 K
(3M HClO 4
+ 1M HCl)
-6.2 -6.0 -5.8 -5.6 -5.4 -5.2 -5.0
log 10
([Sn 4+ free ]/[Sn2+ free ])
(Continued on next page)
CHEMICAL THERMODYNAMICS OF TIN, ISBN 978-92-64-99206-1, © OECD 2012