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

342
A Discussion of selected references
Table A-28: Standard enthalpies of formation of SnCl 4 in HCl, H 2 O 2 solutions
(r = n i /n(SnCl 4 )).
[HCl]/M r(H 2 O 2 ) r(HCl) r(H 2 O) – Δ H (SnCl 4 , sln, 295.15 K)/kcal·mol –1
1.0 50 100 5400 − 5700 152.1 ± 0.6
2.0 50 200 5000 − 5500 151.2 ± 0.8
3.0 50 300 5200 − 5400 149.9 ± 0.7
4.0 50 400 5000 − 5300 149.9 ± 1.0
1.0 85 100 5100 − 5200 152.2 ± 0.4
2.0 85 200 5000 − 5300 152.1 ± 0.5
3.0 85 300 4900 − 5200 149.9 ± 0.7
4.0 85 400 4800 − 5300 149.9 ± 1.5
f
ο
m
[1973VAS/VAS]
The standard enthalpy of formation of tin(II) chloride in perchloric acid solutions has
been investigated calorimetrically. The following reactions were investigated:
SnCl 2 (cr) + y HClO 4 (sln x H 2 O) SnCl 2 (sln x·y H 2 O, y HClO 4 )
(A.55)
SnCl 2·2H 2 O(cr) + y HClO 4 (sln x H 2 O) SnCl 2 (sln (x·y+2) H 2 O, y HClO 4 ) +
2 H 2 O((x·y+2)/2 H 2 O). (A.56)
The standard enthalpy of tin(II) chloride in perchloric acid solutions has been
calculated by
ο
m
f
ο
m
ο
m
Δ H (SnCl 2 , sln, 298.15 K) = ΔH 1 + Δ H (SnCl 2 , cr, 298.15 K)
Δ fH
(SnCl 2 , sln, 298.15 K) = ΔH 2 + Δ fH
(SnCl 2·2H 2 O, cr, 298.15 K)
ο
− 2Δ
H (H 2 O, l, 298.15 K).
ο
Δ fH
(SnCl 2 , cr, 298.15 K) and Δ fHm(SnCl 2·2H 2 O, cr, 298.15 K) were taken from
ο
[1973VAS/VAS2]. The values obtained for Δ fHm
(SnCl 2 , sln, 298.15 K) agreed within
the experimental error with each other regardless whether SnCl 2 (cr) or SnCl 2·2H 2 O(cr)
were used as starting materials. No final result of this work was explicitly given, but the
information obtained was used for thermochemical studies on Sn 2+ and SnCl + ions
[1976VAS/KOK]. The present paper, however, is most valuable, because it contains
experimental details regarding the composition of the solutions employed, the
prerequisite for recalculation of Δ H
[1973VAS/VAS2]
f
ο
m
f
f
m
ο
m
ο
m
(Sn 2+ , 298.15 K) and Δ H
f
ο
m
(SnCl + , 298.15 K).
The heats of dissolution of SnCl 2 (cr) and SnCl 2·2H 2 O(cr) in HCl solutions containing
H 2 O 2 have been measured at 25 °C and the standard enthalpies of formation of these
salts have been calculated using the results of [1973VAS/KOK].
CHEMICAL THERMODYNAMICS OF TIN, ISBN 978-92-64-99206-1, © OECD 2012