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

A Discussion of selected references
295
Figure A-18: Low temperature heat-capacity function of SnS 2 (cr).
70
60
–1·mol
–1
C° p,m
/J·K
50
40
30
20
10
exp. data [1953KIN/T OD]
cubic spline
1 Debye (Θ D
= 172 K) and 2 Einstein
(Θ E1
= 369 K, Θ E2
= 415 K) equations
–1
C° p,m
(SnS 2
, cr, 298.15 K) = 70.125 J·K
–1·mol
Integration of (C° p,m
/T)dT from 0 to 52.75 K
and 52.75 to 298.15 K:
S°(SnS 2
, cr, 298.15)/J·K –1·mol –1 = (78.053 + 9.640) = 87.693
0
0 50 100 150 200 250 300
T / K
The results of the authors were essentially confirmed by this review, see values
in parentheses.
ο
C p,m (SnS, α, 298.15 K)/J·K −1·mol −1 = 49.25 (49.25)
ο
S m (SnS, α, 298.15 K)/J·K −1·mol −1 = (77.0 ± 0.8) (76.82)
ο
C p,m (SnS 2 , cr, 298.15 K)/J·K −1·mol −1 = 70.12 (70.13)
ο
S m (SnS 2 , cr, 298.15 K)/J·K −1·mol −1 = (87.4 ± 0.8) (87.69)
[1954BRU]
The author investigated the spectral change of Sn(IV) observed in 1 to 17 M
H 2 SO 4 solutions. At 240 nm, the author observed a continuous decrease of adsorbance
up to 7 M H 2 SO 4 , but above this concentration the spectral intensities increased again.
He concluded that the first spectral change corresponds to the equilibrium Sn 4+ +
2
2SO4
− Sn(SO 4 ) 2 (aq), and determined log 10 β 2 = − 0.85 (apparently neglecting the
changing ionic strength between 1 and 7 M H 2 SO 4 ). This conclusion was reconsidered
in [1957BRU] (see Appendix A). The second step of spectral change was attributed to
the equilibrium Sn(SO 4 ) 2 (aq) + H 2 SO 4 H 2 Sn(SO 4 ) 3 (aq).
CHEMICAL THERMODYNAMICS OF TIN, ISBN 978-92-64-99206-1, © OECD 2012