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

VIII.1 Halide compounds
139
α (monoclinic) → β (tetragonal), 353 K, Δ trs H = (306.0 ± 0.2) J·mol –1 ,
β (tetragonal) → γ (cubic), 600 K, Δ trs H = (2.53 ± 0.2) kJ·mol –1 .
Uncertainties, unless otherwise stated, are those of the experimenter.
The melting point was reported as 666 K [1981CLA/LET]. The heat-capacity
data were fitted to the equations:
ο 353K
p,m 270K
[ C ] (PbSnF 4 , α, T )/J·K –1·mol –1 = − 235.11 + 2.42159 T/K – 0.00365 (T/K) 2
with standard error of estimate = 0.4 J·K –1·mol –1 , leading to
and
ο 600K
p,m 353K
[ C ]
ο
C p,m (PbSnF 4 , α, 298.15 K) = (162.4 ± 0.8) J·K –1·mol –1 ,
(PbSnF 4 , β,T )/J·K –1·mol –1 = − 333.279 + 4.15949 T/K
– 0.01166 (T/K) 2 + 1.09843 × 10 –5 (T/K) 3
with standard error of estimate = 5.6 J·K –1·mol –1 , which are selected here.
From the heat-capacity measurements up to 298 K [1988CAL/WEI], the
selected entropy is:
ο
S m (PbSnF 4 , cr, 298.15 K) = (223.7 ± 0.3) J·K –1·mol –1 .
The enthalpy of formation was measured by alkaline hydrolysis calorimetry by
ο
[1983THO/PER] who reported: Δ fHm(PbSnF 4 , cr, 298.15 K) = − (1371.4 ± 31.8)
kJ·mol –1 . As this datum has not been confirmed by independent measurements, it cannot
be selected by this review.
VIII.1.1.2.2 BaSnF 4 (cr)
This compound decomposes above 673 K before melting [1975DEN/PAN]. The heat
capacity was measured at 7 to 345 K by adiabatic calorimetry [1988CAL/WEI2] and at
310 to 650 K by DSC [1991CAL/WEI]. Combined data in the range 290 to 600 K were
fitted by the following equation
ο 600K
p,m 290K
[ C ] (BaSnF 4 , cr, T )/J·K –1·mol –1 = − 9.43794 + 1.03157 T/K – 0.00219 (T/K) 2
+ 1.62305 × 10 –6 (T/K) 3
with standard error of estimate of 0.8 J·K –1·mol –1 , leading to the selected value
ο
C p,m (BaSnF 4 , cr, 298.15 K) = (146.5 ± 1.6) J·K –1·mol –1 .
From heat-capacity data up to 298 K, the selected entropy is [1988CAL/WEI2]
ο
S m (BaSnF 4 , cr, 298.15 K) = (205.1 ± 0.3) J·K –1·mol –1 .
There is no reported value of standard enthalpy of formation for this
compound.
CHEMICAL THERMODYNAMICS OF TIN, ISBN 978-92-64-99206-1, © OECD 2012