Contributions to the Data on Theoretical Metallurgy: [Part] 11. Entropies of Inorganic Substances: Revision (1948) of Data and Methods of Calculation Page: 80
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80 CONTRIBUTIONS TO DATA ON THEORETICAL METALLURGY
Element.-Anderson (23) (540-2970) and DeVries and Dobry (125)
(98'-2790) measured the heat capacity of Se(c). Relying entirely on
Anderson's data there is computed S298,16-10.00.3, of which 1.95 is
extrapolation below 53.10. This is 0.5 unit lower than the value
reported by Anderson but it agrees with the findings of Slansky and
Coulter (1446), who have intercompared the available data for S(c),
Se(c), and Te(c).
The compilation of spectroscopic data by Moore (364) shows that
three energy levels must be considered in obtaining the entropy of
Se(g) at 298.160. The term values are 0, 1,989, and 2,534 cm.-' and
the quantum weights are 5, 3, and 1, respectively. The translational
entropy from the Sackur equation is 39.021 and the electronic contri-
bution is 3.200, making S;98.16=42.22 0.01 for Se(g).
Max-well and Mosley (3/46) report 2.190.03X10-s cm. as the
interatomic distance in the Se2(g) molecule, corresponding to 1-
314X 10-40. The vibration frequency is 391 cm.-' according to
Herzberg (212). There are computed St+r,298.16-57.10, S8,298.16-1.00,
and Se,298.1l62.18. The sum is S098.,16-60.30.3.
Selenium Ion.-The National Bureau of Standards tables (370)
list S98.j6,=41.5 for Se--(aq.).
Oxide.-The entropy of SeO(g) is estimated here as Ss98.16= 56.0
Hexafluoride.-From data given by Yost, Steffens, and Gross
(512), Yost (505), Yost and Claussen (508), and Sachsse and Bar-
tholom" (409), the following molecular constants are available:
11 I-13365X10-40, w 708(1), w2 662(2), w-405(3), z4
245(3), w5-461(3), w06787(3), and symmetry number-24. There
are computed S,+T,2 8.16-63.05, S ,-. 12.08, and S'9s.16= 75.1 1.0.
Acids and Ions.-The National Bureau of Standards tables (370)
list the following values: H)SeO4(aq.), S98.16--5.7; HSeO4(aq.),
S9S.1-22.0; SeO4--(aq.), S98.16-05.7; H2SeO3(aq.), S29s.16-45.7:
HSeO3-(aq.), S s.1630.4; SeO3 (aq.), 298.16--3.9; H2Se(aq.),
S98.16"=39.9; and HSe-(aq.), S'9s.16-50.6.
Element.-Anderson (9) (610-2970) and Nernst and Schwers (377)
(20'-900) have measured the heat capacity of Si(c). The two
sets of data yield S298.16=4.500.05. The extrapolation is 0.007
Spectroscopic data compiled by Moore (364) shows that three
energy levels are involved in deriving the entropy of Si(g) at 298.160.
The term values are 0, 77.06, and 223.14 cm.-' and the quantum
weights are 1, 3, and 5, respectively. These states add 4.191 to the
Sackur equation to make S298.16--40.13 +0.01.
Oxides.-The heat capacity of SiO2 (quartz) was measured by
Anderson (20) (530-2970), Giinther (206) (710-89'), and Nernst (373)
(250-2330). Employing all the data, there is obtained S98.16 -10.00
0.10, of which 0.19 is extrapolation below 28.20. This result is
identical with the calculation of Mosesman and Pitzer (366).
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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/m1/84/: accessed April 18, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.