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

A Discussion of selected references
341
[1973VAS/KOK]
The heats of dissolution of metallic tin in hydrochloric acid solutions of hydrogen
peroxide have been measured calorimetrically at 25 °C and ionic strengths 1, 2, 3, and
4 M HCl. The enthalpies of formation of SnCl 4 in these solutions have been calculated.
According to the authors a typical dissolution experiment can be represented
by the following equation:
β-Sn + 49.1 H 2 O 2 (sln 105.4H 2 O, 4.0HCl) + 197.0 HCl(sln 26.2 H 2 O, 0.25 H 2 O 2 )
SnCl 4 (sln 5175 H 2 O, 193 HCl, 47.1 H 2 O 2 ) + 47.1 H 2 O 2 (sln 110 H 2 O, 4.0 HCl,
0.021 SnCl 4 ) + 193 HCl(sln 26.8 H 2 O, 0.24 H 2 O 2 , 0.005 SnCl 4 ) + 4 H 2 O(sln 1294 H 2 O,
48.2 HCl, 11.8 H 2 O 2 , 0.25 SnCl 4 ). (A.52)
The slight stoichiometric inconsistencies in Eq. (A.52) above are
inconsequential and due to rounding errors.
ο
m
Δ fH
(H 2 O 2 , sln 105.4 H 2 O, 4.0 HCl) = Δ fHm
(H 2 O 2 , sln 110 H 2 O, 4.0H Cl,
ο
0.021 SnCl 4 ) = Δ H (H 2 O 2 , sln ∞ H 2 O),
ο
m
Δ fH
(HCl, sln 26.2 H 2 O, 0.25 H 2 O 2 ) = Δ fHm(HCl, sln 26.8 H 2 O, 0.24 H 2 O 2 ,
ο
0.005 SnCl 4 ) = Δ H (HCl, sln 26.2 H 2 O)
f
ο
m
Δ H (H 2 O, 0.037 HCl, 0.009 H 2 O 2 , 0.0002 SnCl 4 ) = Δ H
ο
ο
f
f
f
ο
m
m
m
(H 2 O, l).
Consequently Eq. (A.52) can be simplified to Eq. (A.53)
β-Sn + 2 H 2 O 2 (sln ∞ H 2 O) + 4 HCl(sln 26.2 H 2 O) SnCl 4 (sln) + 4 H 2 O(l).
(A.53)
Thus the enthalpy of formation of SnCl 4 in these solutions can essentially be
obtained by Eq. (A.54):
ο
m
ο
ο
Δ fH
(SnCl 4 , sln) = Δ rHm(A.52) − 4Δ fHm(H 2 O, l) + 2Δ fHm(H 2 O 2 , sln ∞ H 2 O)
ο
+ 4Δ H (HCl, sln 26.2 H 2 O). (A.54)
f
m
ο
m
Using the value for Δ fH
(H 2 O, l) given by CODATA [1989COX/WAG] and
ο
ο
the values for Δ fHm
(H 2 O 2 , sln ∞ H 2 O) and Δ fHm
(HCl, sln 26.2 H 2 O) given by
[1982WAG/EVA] essentially the same results were obtained as those listed by the
authors (Table A-28).
The results of this work are the basis for the determination of standard
enthalpies of formation of tin compounds, and are accepted by the Review Team for
recalculations.
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CHEMICAL THERMODYNAMICS OF TIN, ISBN 978-92-64-99206-1, © OECD 2012