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

348
A Discussion of selected references
[1974POU]
ο
Pourbaix’s data on ΔfG m
(Sn 2+ ο
) and ΔfG m
(Sn 4+ ) were taken from [1952LAT] and
supplied in these cases no additional information.
[1975DAV/DON]
Tritin(II) dihydroxide oxide sulfate, Sn 3 (OH) 2 OSO 4 , was prepared by slow hydrolysis of
tin(II) sulfamate. Crystals so obtained were better for structure determination but
otherwise identical in every respect to the basic sulfate precipitated from aqueous
solution [1967DAV/DON]. The crystal structure of this compound was determined
from X-ray diffractometer data by Patterson and Fourier methods. Crystals are
orthorhombic and piezoelectric, space group Pbc2 1 with Z = 4 in a unit cell of
dimensions a = (4.983 ± 0.002) Å, b = (13.128 ± 0.005) Å, c = (12.214 ± 0.005) Å. The
structure was refined by least-squares methods to R 0.028 for 1070 reflections. The
structure contains discrete ring [Sn 3 O(OH) 3 ] 2+ basic ions which have Sn in two different
environments: one Sn is bonded to all three ring oxygens to give trigonal pyramidal
co-ordination with short Sn–O, and the remaining Sn atoms are bonded to two ring O
atoms with short Sn–O (< 2.16 Å), and has O atoms from separate SO 4 groups at longer
(> 2.40 Å) distances. These latter Sn atoms have distorted square-pyramidal oxygen
environments.
[1975DEM/KOS]
The calorimetric data on the arsenides measured over the temperature range 55 to 310 K
were used to calculate the standard thermochemical data; these data have been
rediscussed by Koshchenko et al. [1980KOS/DEM] extending the calculations to 5 K.
[1975FED/BOL]
Potentiometric measurements using a tin amalgam electrode have been performed to
study the formation of the binary chlorido and bromido, as well as the ternary chloridobromido
complexes of tin(II) at 25 °C in NaClO 4 media (I = 0.5, 1.0, 3.0, 4.0 and
6.0 M). The formation constants of the binary bromido complexes for I = 0.5 were
determined in [1975FED/BOL], while for the other ionic strength they were taken from
[1969FED/BOL]. The authors concluded the formation of three binary chlorido species
2 q
( SnCl
− 2− x y
q
, q = 1, 2, 3) and four ternary complexes ( SnClxBr
− y
, (x,y) = (1,1), (1,2),
(2,1) and (1,3)). A slightly modified form of the Vasil'ev equation has been applied to
calculate the thermodynamic formation constants. The graphical presentation of the
experimental data are provided only for I = 3 M. Based on this information, c.a. 40% of
the original ionic medium was substituted by NaCl/NaBr for the investigations of the
binary complexes, while the NaClO 4 medium was entirely replaced during the
measurements of the ternary complexes. Therefore, an uncertainty of ± 0.4 has been
assigned to the log10
β q values of the binary complexes, while the formation constants
of the ternary complexes were not considered any further in this review.
CHEMICAL THERMODYNAMICS OF TIN, ISBN 978-92-64-99206-1, © OECD 2012