Contributions to the Data on Theoretical Metallurgy: [Part] 11. Entropies of Inorganic Substances: Revision (1948) of Data and Methods of Calculation Page: 63
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ENTROPIES OF INORGANIC SUBSTANCES AT 298.160K.
Element.-Elson, Smith, and Wilhelm (143) (150-230), Kelley (275)
(530-2900), and Shomate (296, 426) (540-2970) measured the heat
capacity of Mn(a). The data of the latter two investigators give
Si2.o=0.48 (extrapolation), S2s.1--S 2.0= 7.11 (measured), and S29,.18-
7.590.04. This value is adopted.
Shomate (296, 426) (530-2970) also measured the heat capacity of
Mn(*y). His data yield S2.0= 0.49 (extrapolation), S298.16- S2.0= 7.23
(measured), and S29,16= 772 0.04.
Kelley (296) computed S298.16-41.500.01 for Mn(g) by means of
the Sackur equation, with R In 6 added to account for the quantum
weight of the one state effective at 298.160.
Manganous Ion.-Kapustinsky (239) has reported S9.16= -19.1+-
0.6 for Mn++(aq.) from thermal data for manganese carbonate.
Oxides.-Millar (359) (700-3010) measured the heat capacity of
MnO(c). The data yield S00.8= 2.22 (extrapolation) and S98s.16=
The entropy of MnO(g) is estimated roughly from the vibration
frequency (212), 836 cm.-1, and an assumed value of the moment of
inertia, 60X 10-4. The result is S98s.6=53.0 1.5.
The heat capacity of MnO2(c) was measured by Kelley and Moore
(291) (530-2950) and Millar (359) (720-294). The results of the two
investigations are not in agreement, and Kelley and Moore (291) have
shown that this is attributable largely to an error in Millar's calcula-
tions of his data. From Kelley and Moore's data, there are obtained
S0.12=0.60 (extrapolation), S,9s.8--S0.12= 12.08 (measured), and
S 298s.,6-12.68 0.10.
Kapustinsky and Bayuskina (240) have suggested S298.16=22.9 for
Mn203 (c), calculated from dissociation-pressure measurements of
MnO2(c). No attempt is made to estimate the uncertainty in this
In addition, Millar (359) (720-3060) measured the heat capacity of
Mn304(c). The data yield S298.18= 35.50.7, the extrapolation being
4.67 below 70.80.
Carbide.-Kelley and Moore (291) (520-2960) measured the heat
capacity of Mn3C(c). The data yield S20.12--1.24 (extrapolation),
S298.16-S50.12= 22.38 (measured), and S98.16- 23.6 0.2.
Carbonate.-Anderson (16) (550-2970) measured the heat capacity
of MnCO3 (rhodochrosite). Hisresults give S 6.2- 1.65 (extrapolation),
S298.16-S6.2- 18.87 (measured), and S;98.16 20.5 0.3.
Chloride.-The heat capacity of MnCl12(c) was measured by Kelley
and Moore (292) (53'-295') and Trapeznikova and Miljutin (489,
490) (140-1310). The results of the two investigations disagree by
3 to 4 percent over the common temperature range and those of
Kelley and Moore are adopted. There are obtained S0.126.02 (ex-
trapolation), S',s.- -S0.12-21.97 (measured), and S298.16=28.0 ~0.5.
There have been added 3.27 units to the extrapolated portion, to
take account of unextracted magnetic entropy. The uncertainty
figure has been increased to allow for error in this procedure.
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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/m1/67/: accessed April 19, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.