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

VIII.1 Halide compounds
153
The value recommended by [1991GUR/VEY] falls within the error limits.
Berezovskii et al. [1980BER/STE] measured the heat capacity of SnBr 2 (cr) in
the 5.5 to 322 K temperature range, and reported 87 points (see Appendix A). For
ο
–1
standard conditions the data are C p,m (SnBr 2 , cr, 298.15 K) = (78.97 ± 0.16) J·K
–1·mol
and S (SnBr 2 , cr, 298.15 K) = (153.0 ± 0.3) J·K –1·mol –1 .
ο
m
Brumleve et al. [1992BRU/WAL] reviewed the molar heat capacities for the
condensed phases of SnBr 2 . Pankratz [1984PAN] extrapolated the low-temperature
measurements of [1980BER/STE]. Gardner and Preston [1991GAR/PRE] determined
the molar heat capacity of the solid, at T = 350 to 500 K, and the liquid, at T = 520 to
800 K, using differential scanning calorimetry. The heat capacity over the temperature
ο
p,m
range of 350 to 800 K is given by: C (SnBr 2 , l, T )/J·K –1·mol –1 = (70.18 ± 0.33) +
(0.04933 ± 0.00107) T/K. Their extrapolated value of the heat capacity at 298.15 K is
78.60 J·K –1·mol –1 .
Brumleve et al. [1992BRU/WAL] further combined the data from their own
study with that of [1991GAR/PRE] to calculate the molar heat capacity of the solid
from 298.15 to 507 K and of the liquid from 507 to 1000 K. The parameters for the
polynomials describing the temperature variation of the molar heat capacities are listed
in Table VIII-5.
Table VIII-5: Parameters for the temperature variation of the molar heat capacity of
SnBr 2 using the equation (after [1992BRU/WAL]): C ο p,m
(SnBr 2 , (s, l, or g), T )/
J·K –1·mol –1 = A + B T/K + C (T/K) 2 + D (T/K) –2 for condensed-phase species (298 < T/K
< 1000) and for the gas (298 < T/K < 6000). p° = 101325 Pa.
A B C D
SnBr 2 (s) 4.1097 × 10 1 1.2158 × 10 –1 − 6.3618 × 10 –5 6.4755 × 10 5
SnBr 2 (l) 8.8328 × 10 1 − 4.6988 × 10 –3 4.0879 × 10 –5 − 5.4090 × 10 4
SnBr 2 (g) 5.8169 × 10 1 1.5400 × 10 –5 − 1.7100 × 10 –9 − 1.5911 × 10 5
Brumleve et al. [1992BRU/WAL] adopted the entropy data from
[1980BER/STE] for the solid as 153.00 J·K –1·mol –1 ; they also calculated the entropy for
the liquid and gas phases (176.9 J·K –1·mol –1 and 328.764 J·K –1·mol –1 respectively)
employing the third-law procedure, the heat-capacity data as in Table VIII-5 and
spectroscopic data. Error estimates are not given.
The values of the heat capacity and entropy of SnBr 2 (cr) selected by this
review are from Berezovskii et al. [1980BER/STE]:
ο
C p,m (SnBr 2 , cr, 298.15 K) = (78.97 ± 0.16) J·K –1·mol –1 ,
ο
S m (SnBr 2 , cr, 298.15 K) = (153.0 ± 0.3) J·K –1·mol –1 .
CHEMICAL THERMODYNAMICS OF TIN, ISBN 978-92-64-99206-1, © OECD 2012