Contributions to the Data on Theoretical Metallurgy: [Part] 11. Entropies of Inorganic Substances: Revision (1948) of Data and Methods of Calculation Page: 56
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56 CONTRIBUTIONS TO DATA ON THEORETICAL METALLURGY
Ferrous Bromide.-Miljutin and Nachimowitsch (356) (120-1100)
have made some rather uncertain-appearing heat-capacity measure-
ments of FeBr2(c). The data hardly warrant an entropy calculation,
but there is estimated S'-98.16=34.22.0, of which 0.81 is extrapola-
tion below 11.90
Carbide.-Andes (27) (102'-3240) measured the heat capacity of
carburized iron, extrapolated his results to the composition FeC,
and calculated S'98.18=23.55. More recently, Seltz, McDonald, and
Wells (419) (680-2980) measured the heat capacity of iron containing
1.354 weight-percent carbon which showed no signs of graphite.
They computed the heat capacity of Fe3C(c) from their results by
subtracting that of the contained iron in excess of the composition
Fe3C. The entropy of Fe3C(c) was evaluated as S2098.16=25.7l 1.0,
of which 2.57 is extrapolation below 680. In addition, Naeser (369)
(850-2980) has measured the heat content of Fe3C(c). His data
were considered by Schwarz and Ulich (414), who attempted to extract
true heat capacities and calculated S298.16823.9.
The author (274) calculated AS298.18=2.99 as the entropy of forma-
tion of Fe3C(c) from equilibrium data for the reactions 3Fe(a)+
CH4(g)- Fe3C(a)+2H2(g) and 3Fe(a)+2CO(g)= Fe3C(a)+CO2(g).
This figure leads to Ss98.18=23.8 for Fe3C (a), in fortuitous agreement
with Schwarz and Ulich's calculation.
The mean of these several results, S298.16 =24.2 1.0, is adopted.
Ferrous Carbonate.-The heat capacity of FeCO3 (siderite) was
measured by Anderson (16) (540-2970). Calculation gives S298.18-=
22.2 0.4, of which 2.33 is extrapolation below 56.20.
Ferrous Chloride.-Kelley and Moore (292) (530-295') and Trapez-
nikova and Shubnikov (491) (160-1270) have measured the heat
capacity of FeC12(c). The data of the latter are erratic and are given
little weight. There are obtained S,0.12= 5.19 (extrapolation), S,,8.16=
23.46 (measured), and S2098.18=28.7 +0.5.
Ferrous Chromite.-Shomate (425) measured the heat capacity of
FeCr204(c). The data yield S53.09= 4.38 (extrapolation), S298.16-
S53.09= 30.52 (measured), and S298.,8= 34.9 0.4.
Ferrous Iodide.-Some rather inadequate heat-capacity measure-
ments of FeI2(c) were made by Miljutin and Parfenowa (357) (110-
1300). The data probably do not warrant an entropy calculation,
but there is estimated Ss98.16= 36.8 2.0, of which 0.35 is extrapolation
Nitride.-Kelley (274), from data for the reaction 2Fe4N (c) + 3H2(g)
=8Fe(a) +2NH3, has estimated Sz98s.6= 37.4 for Fe4N(c). This value
may be in error, probably high, by a few units.
Ferrous Silicate.-The heat capacity of Fe2SiO4 (fayalite) was
measured by Kelley (282) (520-2960). This substance has a "hump"
in its heat-capacity curve at 65.00 which makes extrapolation difficult;
and, as indicated by Shomate (430), the original entropy calculation
probably is too high. Recalculation gives S20.12= 3.05 (extrapolation),
S s.8.16- 0.12 31.69 (measured), and S18s.16= 34.7 0.4.
Ferrous Sulfide.-Anderson (12) (570-2960) measured the heat
capacity of FeS(c). Calculation gives S,.2--1.43 (extrapolation),
S2,s.1- 8.2= 14.68 (measured), and S98.16= 16.1 0.3.
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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/m1/60/: accessed April 20, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.