Contributions to the Data on Theoretical Metallurgy: [Part] 11. Entropies of Inorganic Substances: Revision (1948) of Data and Methods of Calculation Page: 35
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ENTROPIES OF INORGANIC SUBSTANCES AT 298.160K.
61.55= 2.46 (transition), S8.09--S .55-= 1.23 (crystals I), AS*8.09 =
68.09=2.93 (fusion), Si.6-Ss.o09=--2.61 (liquid), AS 144--81.6
17.69 (vaporization at 1 atm.), AS81.6= 0.21 (correction to ideal gas
state), and S98.16-S1 .61 =9.00 (gas). These figures add to give
Ss98.16=46.22. The result from spectroscopic data is S98.16=47.31
0.01. The difference of 1.1 units, which is of the order of R In 2,
was attributed by Clayton and Giauque to random orientation of
molecules in the crystal lattice of solid CO. The value from spec-
troscopic data is adopted, as it can be in error by only a negligible
The spectroscopic value may be checked by utilizing molecular-
constant data (212, 311), I=15.OX10-40 and w=2155. The result is
S98.16=47.28, the vibrational contribution being negligible.
Dioxide.-The low-temperature heat capacity of CO2 was measured
by Eucken (146) (190-2010), Eucken and Hauck (147) (800-3200),
and Giauque and Egan (178) (150-1900). Giauque and Egan de-
termined accurately the heat of sublimation; the results of their
entropy calculation are adopted. The computed terms are S o=
0.19 (extrapolation), S 194.87-S5= 16.33 (crystals), S94.7=-194.67
30.98 (sublimation at 1 atm. pressure), AS 94.87= 0.09 (correction
to ideal gas state) and S29s.16-S94.67= 3.52 (gas). The sum is
Ss98.18= 51.11 0.10.
Dennison (124) has reported I=71.30X10-40 and w=1,351.2(1),
02= 672.3(2), and 03=2396.4 for the CO2(g) molecule. These figures
lead to S1+r,298.16 50.35, S.298.16= 0.70, and S98.16= 51.05 0.05.
The agreement between the third-law value and that from molecular
constants is excellent. The latter is adopted, as it is subject to less
uncertainty. Gordon (195), using somewhat different molecular
constants, has obtained a satisfactory agreeing value.
Suboxide.-Molecular-constant data listed by Thompson (482),
=1395.2X10-40 and w= 200(2), 550(2), 586(2), 843(1), 1,570(1),
2,200(1), and 2,290(1), enable the calculation of the entropy of
C302(g) There results S+-,298.16=55.05 and S,298.16= 6.49, making
S98s.s= 61.5 0.5.
Monosulfide.-From molecular-constant data (212, 311), 1= 33.88 X
10-40 and co=1,279, there are calculated So+r,298.16=50.25 and S ,298.1=
0.03, making S98s,,6= 50.28 0.10 for CS(g).
Disulfide.-Brown and Manov (60) (150-2980) measured the heat
capacity of CS2. Calculation yields S4.9 = 0.64 (extrapolation),
o o os 1,049
S11.1-S4.98= 17.92 (crystals), AS.--1.1=6.-- 6.51 (fusion), and
S~os.16-S~s1.1=11.09 (liquid). The sum is S,9s.16=36.20.2 for
The heat and free energy of vaporization of CS2(1) are AH298.186
6,682 and AF2981.6=441 (270), giving AS29s.1= 20.93. Addition of
this entropy increment to the value for CS2(1) yields Si98.1= 57.10.4
for CS2(g). A more reliable value for CS2(g) is obtained from molecular-
constant data (311), which are I=260 X 10-40, w= 655(1), 2= 397 (2),
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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/m1/39/: accessed April 19, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.