Contributions to the Data on Theoretical Metallurgy: [Part] 11. Entropies of Inorganic Substances: Revision (1948) of Data and Methods of Calculation Page: 28
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28 CONTRIBUTIONS TO DATA ON THEORETICAL METALLURGY
15.5 waves per cm., need be considered. These levels are designated
2Pl/2 and 2P3/2, respectively, with quantum weights of 2 and 4. It is
found that 3.562 is to be added to the translational entropy given by
the Sackur equation, making Ss.16= 36.660.01 for B(g).
Oxides.-Kelley (281) (52o-2960) measured the heat capacity of
B203(c). His data give S98.16= 13.040.07, of which 0.68 is extrapo-
lation below 53.10.
Molecular-constant data for BO(g) (212, 311) yield S298.16=48.60=
Carbide.-The heat capacity of B4C(c) also was investigated by
Kelley (281) (540-2950). The data yield S9.16=6.47+0.03, the
extrapolation below 53.10 being 0.047.
Tribromide.-Spencer (452) has computed the entropy of BBr3(g)
from the moments of inertia, 11=1,392X 10-40 and I2I3=--696X 10-40,
and the vibration frequencies, 151.2(2), 279(1), 375.3(1), and 812(2).
The molecule is planar and nonlinear, so the symmetry number is 6.
The calculation gives S+r,298.16=--69.19 and S,,298.16--8.30, making a
total of S~98,6= 77.5 0.5.
Trichloride.-The entropy of BC13(g) was calculated by Spencer
(452) from the moments of inertia, I1=528.6X 10-40 and 12=13=
264.3X10-40, the vibration frequencies, 243.2(2), 465.8(1), 471(1),
and 965.2(2), and the symmetry number 6. These molecular con-
stants yield So+,,298.1=64.04, S,298.16= 5.25, and S98.16= 69.3 0.5.
Trifluoride.-Eucken and Schr6der (150) (120-1730) have measured
the heat capacity and heats of transition and fusion of BF3 and have
used the data in computing S98.16= 61.17 for BF3(g). Spencer (452)
has called attention to several errors in their calculations and has
obtained S298.16=60.80 from essentially the same basic data. He
computes S12.6= 0.55 (extrapolation), S42.15-S12.6= 18.42 (crystals
II), S144.46-S 42.15= 0.74 (transition and crystals I), AS*.46=-144.46
7.02 (fusion), S154.5-S144.46=1.65 (liquid), AS154.5=-154.5=28.55
(vaporization at 0.2185 atm.), AS154.5=0.04 (correction to ideal gas
state), AS54.5= -3.02 (compression to 1 atm.), and S98s.1-S154.5-
6.85 (gas). The total is S29.16=60.800.5.
Spencer (452) also has computed the entropy of BF3(g) from molec-
ular-constant data. The moments of inertia are 11=157.7 X 10-40 and
12 3= 78.84 X 10-40. According to data presented by Gage and
Barker (164) the vibration frequencies for the normal isotopic BF3
mixture are 481(2), 697(1), 888(1), and 1,456(2). These figures and
symmetry number 6 yield S t+r,298.16= 58.80, Sv298.16= 1.90, and
S298.16=60.7 0.5. This value is in good agreement with the third-
law result and is the value adopted.
Hydrides.-Molecular-constant data are available for BH(g) and
BD(g) (212). Calculation gives S89s.16=41.010.10 for BH(g) and
Ss .1, 42.460.10 for BD(g).
Element.-The heat capacity of solid bromine was measured by
Latimer and Hoenshel (321) (140-2530) and Suhrmann and von Lide
(478) (200-1550). The results of the former investigators are used
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Kelley, K. K. Contributions to the Data on Theoretical Metallurgy: [Part] 11. Entropies of Inorganic Substances: Revision (1948) of Data and Methods of Calculation, report, 1950; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc12637/m1/32/: accessed April 20, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.