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

300
A Discussion of selected references
[1958KOV]
The solubility product of “tin(II) hydroxide” defined by
“Sn(OH) 2 (s)” + 2 H + Sn 2+ + 2 H 2 O(l)
was determined by a polarographic method at 22 °C to be log
ο
10 s,0
K = − 28.1.
(A.33)
The author claims to have measured pH and concentration of Sn 2+ at the
beginning of “Sn(OH) 2 (s)” precipitation from chloride solution. Separately precipitated
tin(II) hydroxide was analysed and found to have a molar ratio n(Sn)/n(OH) = 1/2 and
was contaminated by traces of chloride only. However, this does not mean that the
precipitate had this composition when the reverse of Reaction (A.33) commenced. The
ο
extremely low value of log10 K s,0
seems to indicate that Sn 21 Cl 16 (OH) 14 O 6 (cr)
[1981SCH/NES] was the initial product. When the data of [1930RAN/MUR] are
analysed assuming “Sn(OH) 2 (s)” precipitation the corresponding value would be
ο
log K = − 28.56.
10 s,0
[1958ORR/CHR]
In this paper high temperature enthalpy increments for tin(II) sulphide (see Table A-13)
and tin(IV) sulphide (see Table A-14) were determined by drop calorimetry.
Table A-13: SnS, measured enthalpy increments above 298.15 K.
T/K [H°−H°(0)]/J·mol −1 T/K [H°−H°(0)]/J·mol −1 T/K [H°−H°(0)]/J·mol −1
388.4 15247 764.9 35707 980.3 49263
389.9 15331 793.7 37673 1071 54451
482.4 20058 843.6 40769 1114.1 57087
483.6 20142 863.6 42192 1122.5 59932
580.5 25414 868.1 42652 1143.8 73070
604.5 26586 872.8 42903 1161.4 91438
675.7 30686 876.3 43531 1185.1 93195
726.6 33573 892.1 44368 1225.1 96249
Table A-14: SnS 2 , measured enthalpy increments above 298.15 K.
T/K [H°−H°(298)]/J·mol −1 T/K [H°−H°(298)]/J·mol −1 T/K [H°−H°(298)]/J·mol −1
400 7155 592 21338 980.3 49263
489.6 13640 594.9 21757 1071 54451
491.2 13807 603.1 22217 1114.1 57087
498.7 14435 621.6 23723 1122.5 59932
524 16150 692.6 29121 1143.8 73070
561.2 19037 762.1 34476 1161.4 91438
CHEMICAL THERMODYNAMICS OF TIN, ISBN 978-92-64-99206-1, © OECD 2012