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

384
A Discussion of selected references
The compound Sn 21 Cl 16 (OH) 14 O 6 is structurally identical with crystals
investigated by [1963DON/MOS], although the composition of the latter was found to
be Sn 4 Cl 2 (OH) 6 . Von Schnering et al. could not explain this fact.
[1982MAC]
This paper describes the composition of and the minerals identified in ‘copper’
concretions found on shipwrecks off the Western Australian Coast. Since the copper,
brass and bronze artefacts examined have been in a marine environment for periods of
up to 350 years they provide valuable information on the long-term stability of these
metals to corrosion. Concretions formed on bronzes have tin present in the concretions
mainly as the tin(IV) oxide, SnO 2 , cassiterite with tin(II) oxide sulfate (Sn 3 O 2 SO 4 ) as a
minor phase.
[1983BER/STE]
Berezovskii et al. [1983BER/STE] measured the heat capacity of tin tetrabromide at
112 points in the temperature range 6.66 to 336.2 K in a vacuum adiabatic calorimeter
with a nickel bulb [1978BER/PAU], and calculated entropy, enthalpy and Planck
function of tin tetrabromide phases α-SnBr 4 , (monoclinic to 287 K), β-SnBr 4 and
SnBr 4 (liquid) The average deviation of the experimental heat capacities from the
smoothed curve was 0.2% below 20 K, 0.05% in the range 20 to 285 K, and 0.1% for
the liquid phase (306 to 336 K). For the β-phase (the region of existence of β-SnBr 4 , is
287 to 302 K), three series of experimental points were obtained in the range from 290.9
to 301.9 K (see Table A-49) with relative errors up to 1%. The C p data for the β-phase
showed above 296 K a “prefusional” increase and the smoothed values selected by the
authors are somewhat ambiguous, see Figure A-45. The influence of this discrepancy on
o
o
o
the calculated thermodynamic quantities S
m
(SnBr 4 , β, 298.15 K), H (T) − H (0) and
o
Φ (T) is negligible when all other experimental errors are taken into account. In
addition to C p data listed in Table A-49 Bereszovkii et al. determined thermodynamic
quantities for the polymorphic phase transition and fusion of SnBr 4 , see Table A-50.
CHEMICAL THERMODYNAMICS OF TIN, ISBN 978-92-64-99206-1, © OECD 2012