Contributions to the Data on Theoretical Metallurgy: [Part] 11. Entropies of Inorganic Substances: Revision (1948) of Data and Methods of Calculation Page: 92
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92 CONTRIBUTIONS TO DATA ON THEORETICAL METALLURGY
Molecular-constant data for SnO(g) listed by Herzberg (212) corre-
spond to I-79.1 X10-40 and w=c819. There are obtained SI+r,298.16
-55.267, S ,298.16=0.192, and S98s.16 55.460.10.
Millar (361) (710-2900) also measured the heat capacity of SnO2(c).
The data yield S0 .80o-1.38 (extrapolation), S98s.1 -So.so80-11.11
(measured) and S298s.16 12.5 0.3.
Sulfide.-From molecular-constant data listed by Herzberg (212),
I-178X 10-40 and c-487 for the SnS(g) molecule. Calculation
gives St+r,298.16-57.22, Sv,298.16=0.69, and S,29.16 57.9 f 0.3.
Tetrabromide.-Landolt-B6rnstein (311) records 1=12=13=2,160
X 10-40 for the SnBr4(g) molecule and the vibration frequencies are
68 (2), 88 (3), 221 (1), and 280 (3), according to the work of Welsh,
Crawford, and Scott (500). There are computed S+r,298.16=72.17,
SV,298.16=26.07, and S2os.,1698.2 1.0.
Tetrachloride.-Yost and Blair (507) give 3.8110-s cm. as the
C1-C1 distance in the SnC14(g) molecule, corresponding to 11=J2-I3-
855 X 10-40. From the work of Welsh, Crawford, and Scott (500), the
vibration frequencies are 106 (2), 131 (3), 368 (1), and 403 (3). The
calculations yield St+r,298.16--67.86, Sv,29s.16-19.40, and S2098.16- 87.3
1.0 for SnC14(g). Yost and Blair (507) calculated a virtually identical
From the above entropy value and the entropy of vaporization
(270), S298.16-62.21.5 is calculated for SnC14(1). Latimer (314)
obtained S99S.16-61.8 from heat-capacity measurements (890-2940).
The agreement is well within the limit of uncertainty of either result.
Telluride.-McAteer and Seltz (347) found AS,98.160.0 for the
reaction Sn(c)+Te(c)= SnTe(c). This leads to S298.16=24.21.0 for
Element.-The heat capacity of Ti(c) was measured by Kelley (287)
(530-2960). The entropy calculation yields S20.12-0.40 (extrapolation),
S98.16-S0.12 6.84 (measured), and S298.16 7.240.05.
For Ti(g), the compilation of 'Moore (364) shows that three energy
levels must be considered in deriving the entropy at 298.16'. The
term values are 0, 170.132, and 386.873 cm.-', and the quantum
weights are 5, 7, and 9, respectively. These levels add 5.545 to the
translational entropy, 37.531, to make S29s.1 643.080.01 for Ti(g).
Oxides.-Shomate (429) (520-2970) measured the heat capacity of
TiO(c). His data yield S52.00-0.25 (extrapolation), S098.16 -S2.00= 8.06
(measured), and S298.16- 8.31 10.04.
Molecular-constant (212) and spectroscopic (311) data for TiO(g)
are used in obtaining the entropy. The moment of inertia is 52.3 X
10-40 and the vibration frequency is 1,004. Three electronic energy
levels with term values 0, 66, and 140 cm.-1 are concerned; the quan-
tum weight is 2 in each instance. These figures yield SI+7,298.16-52.222,
Sv,298.16-0.092, and So,29s.16=3.489. The sum is S298.16=55.800.10
The heat capacity of Ti203(c) was measured by Shomate (429)
(530-2970). There are obtained S2.oo00-0.50 (extrapolation), S~s.16-
S2.00o= 18.33 (measured), and S98.16= 18.83 0.09.
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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/m1/96/: accessed April 23, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.