Contributions to the Data on Theoretical Metallurgy: [Part] 11. Entropies of Inorganic Substances: Revision (1948) of Data and Methods of Calculation Page: 23
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ENTROPIES OF INORGANIC SUBSTANCES AT 298.16 0K.
of inertia. From the values, I=489X10-40 and w=269, there are
obtained Si+r.298.16= 59.28, S 298.16= 1.60, and S298.16=60.90.2.
Oxides.-Anderson (10) (Sb203, 590-2950; Sb204, 590-2850; and
Sb20O, 600-2930) has made low-temperature heat-capacity measure-
ments of three antimony oxides.
For Sb203(c) there is obtained S2,,.1 =29.40.6, of which 4.09 is
extrapolation below 56.230.
A rough value of the entropy of Sb40O(g) may be obtained from
that of the solid, 2 X 29.4, and the entropy of sublimation, AS298.16=42.9
(270). The result is S298s.6= 102, in which the error may be several
Anderson's data for Sb204(c) yield S56.23=4.31 (extrapolation) and
S29s.16-S86.23=26.04 (measured), making S298.168=30.4 0.7.
The corresponding figures for Sb205(c) are S56.23= 2.54 (extrapola-
tion) and S29.1- S86.23= 27.32 (measured). The sum is S298.1= 29.9+
1.0. The estimated error includes allowance for uncertainty in cor-
recting the heat-capacity values for water and lower oxide impurities.
Sulfide.-From heat and free-energy equations given by Kelley
(273) there is estimated S298.16= 39.6 for Sb2S3(c), in which the error
may be a few units.
Trichloride.-Howard and Wilson (217) have considered the pris-
matic SbC13(g) molecule and have obtained 134(2), 165(1), 320(2),
and 360(1) as the vibration frequencies, the numbers in parentheses
being the degrees of freedom. The Sb-Cl distance was given as
2.30X 10-8 cm. and the valence angle as 94'. A slightly different
set of frequencies was reported by Hemptinne, Wouters, and Fayt
(209), 130(2), 155(1), 320(2), and 360(1). From Howard and Wilson's
figures the moments of inertia are 11=660X 10-40 and 12=I 3=470X
10-40. These, with the Sackur-Tetrode equation and the symmetry
number 3, yield SI+,,298.16 68.77. The vibrational entropy is S ,298.16
12.00, making S209s,1680.8 1.0 for SbCl1(g).
The free energy and heat of sublimation of SbC13(c) have been re-
ported (270) as AF298.16=5,111 and AH298.16=15,855, corresponding
to an entropy of sublimation of AS29.1-=36.03. This figure and the
entropy of the gas yield S$29.16= 44.7 2 for SbCl3(c).
Element.-Clusius (79) (100-890) and Eucken (146) (170-940) have
made heat-capacity measurements of solid and liquid argon. Eucken
and Hauck (147) determined the melting point and heat of fusion,
and Frank and Clusius (162) the boiling point and heat of vaporiza-
tion. The data of Clusius and Frank and of Eucken differ appreciably.
Two independent calculations of the third law value of the entropy
will be given for comparison with the more reliable result obtainable
from the Sackur equation.
Clusius and Frank (98) have summarized their data in an entropy
calculation for 87.290, the normal boiling point. Their results are:
S10o=0.303 (extrapolation), S83.78s-So=-8.815 (crystals), AS;3.78--
280.8/83.78=3.352 (fusion), S87 .29-S83.78- 0.413 (liquid), AS87.29
1,557.5/87.29= 17.843 (vaporization), and AS87.29--0.125 (correction
to ideal gas state). These values add to give S87.2930.85. To bring
the gas to 298.160 there must be added 6.104 (calculated from a
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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/m1/27/: accessed April 24, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.