Contributions to the Data on Theoretical Metallurgy: [Part] 11. Entropies of Inorganic Substances: Revision (1948) of Data and Methods of Calculation Page: 25
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ENTROPIES OF INORGANIC SUBSTANCES AT 298.160 K.
There are calculated S+,298.16=-67.78, S,298.16= 10.41, and 298.16-
78.21.0. The last value agrees with the calculations of Yost and
Anderson. The older calculation of Yost and Sherborne (510) is
The heat and free energy of vaporization of AsC13(1) have been
calculated as AH298.18= 8,692 and AF298s.16= 2,009, from vapor-pressure
data (270). These figures correspond to an entropy of vaporization
of AS298.18= 22.4 which, when combined with the result for the gas,
gives S298.16=55.8-+2 for AsC13().
Trifluoride.-Russell, Rundle, and Yost (407) (130-2880) have
measured the heat capacity of AsF3 and have obtained the entropy
of AsF3 (g) at 298.160 and 1 atm. pressure. The entropy terms are
as follows: S13.34= 0.454 (extrapolation), 867 .21-S 13.34= 30.272
(crystals), AS267.21 267.21=-9.304 (fusion), S 92.5o-S 7.2 2.713
(liquid), AS292.50292.50=29.285 (vaporization at 141.6 mm. pressure),
and AS292.50=0.06 (correction for gas imperfection). These terms add
to give S292.50=72.09 for AsF3(g) under 141.6 mm. pressure. The
correction to 1 atm. pressure is -3.34 and the entropy increment for
increasing the temperature from 292.500 to 298.160 is 0.30. The
final result is S298.18= 69.05 0.15.
Russell, Rundle, and Yost also obtained S29.16-=69.080.10 from
molecular constant data for AsF3(g). This calculation was checked
by the present author to within 0.02 unit. The agreement with the
third-law value is excellent.
The data of Russell, Rundle, and Yost also serve to obtain the
entropy of AsF3(1). From terms listed above, the entropy of AsF3(1)
at 292.500 is S292.50=42.74. The entropy increment for heating the
liquid to 298.160 is 0.58, making SN9s.16=43.3 0.1.
Element.-The entropy of Ba(g) calculated from the Sackur equa-
tion is S298.16=40.670.01. In this instance only one energy level
of unit quantum weight is effective.
Kelley (290) estimated the entropy of Ba(c) as Si9s.16=16.00.5.
Barium Ion.-Latimer, Pitzer, and Smith (325) have obtained
S98s.18= 2.30.3 for the entropy of Ba++ (aq.) from data for the reac-
tion BaCl2.2H20(c) =Ba++(aq.)+2Cl-(aq.) +2H20 (1).
Oxide.-Anderson (17) 560-2990) investigated the heat capacity of
BaO (c). From his data, S,9s.1=16.80.3, of which the extrapola-
tion below 56.20 is 2.56.
From band spectra, Mahanti (342) has obtained I=76.0X10-40
and w=671.5 for BaO(g). These figures yield S -+r,298.16=55.58 and
S~,298.16=0.34. The sum is S29s.18=55.90.5 for BaO (g).
Bromate.-Greensfelder and Latimer (202) (160-2960) measured
the heat capacity of Ba(BrO3)2-H20- Their entropy calculation is in
error, as was indicated by Latimer, Schutz, and Hicks (328). Recal-
culation gives 0.80 unit as the extrapolated portion between 00 and
15.850 and 67.97 as the measured portion between 15.850 and 298.160.
The total is S298.16= 68.8 4 1.5.
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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/m1/29/: accessed April 19, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.