Contributions to the Data on Theoretical Metallurgy: [Part] 11. Entropies of Inorganic Substances: Revision (1948) of Data and Methods of Calculation Page: 59
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ENTROPIES OF INORGANIC SUBSTANCES AT 298.160K.
St+r,298.16=59,55, S,298.16=1.40, S ,298.16= 1.38, and S98.16= 62.3 0.5
Fluoride.-The vibration frequency of the PbF(g) molecule is 505
cm.-1 (212) and the quantum weight of the lowest energy level is 2.
The interatomic distance is estimated here as 2.3 X 10-8 cm., leading
to I= 153 X 10-40. There are computed SI+,298.16= 58.12, S ,298.16= 0.64,
S,,298.16=1.38, and S98.1= 60.1: 0.5 for PbF (g).
Hydride.-Molecular-constant data are available for PbH(g) (212),
1=5.63 X 10-40 and w=1,535. Calculation yields S?+r,298.16= 51.314,
S,298.16=0.009, Se,298.18= 1.378, and S298.1= 52.700.10.
Iodides.-From the heat-capacity data of Nernst and Schwers (877)
(220-960), Lewis and Gibson (831) have calculated the entropy of
PbI2(c) as S2098.18=41.3 by means of their N-formula. As the data
are meager and the extrapolation is large, C, being 7.05 at 22.30, it is
not possible to improve much on this calculation. The uncertainty
may easily be as much as 1.5 units.
A much more reliable value may be obtained from the cell measure-
ments of Gerke (169), which give AS*98.16= -1.2 for the reaction
Pb(c) +I2(c)= Pb(c). This figure leads to Sgs.16=42.20.5 for
For PbI(g), there are computed SI+r,298.16= 62.88, Sv,298.16=2.50,
S;,298.16=1.38, and S98.16= 66.8 0.5 from molecular-constant data
listed by Stevenson (467), 1 =932X 10-40 and w= 164.
Phosphate.-Pitzer, Smith, and Latimer (391) (150--2920) measured
the heat capacity of Pb3 (P04)2 (c). There is computed S98.16 = 84.5
0.4 of which 1.10 is extrapolation below 150.
Selenide.-The entropy of PbSe(g) is estimated here as S299.16=
Silicate.-Kelley (289) (520-2960) has measured the heat capacity
of PbSiO3(c). There are computed S0.12=4.39 (extrapolation),
S298.16-S5o.12=24.33 (measured), and S298.18=28.7 0.3.
Sulfide.-The heat capacity of PbS (galena) was measured by
Anderson (13) (530-2900) and Eastman and Rodebush (139) (630-
2830). The data of Anderson are used in obtaining S2s8.16= 21.8 +
0.5, of which 4.50 is extrapolation below 50.10
Molecular-constant data (212), 1=264 X 10-40 and w=427, give
S~+,,298.16 -59.375, S,298.16=0.803, and S298.16= 60.18 0.10 for PbS(g).
Sulfate.-Anderson (19) (530-2940) and Haas and Stegeman (207)
(830-2980) measured the heat capacity of PbSO(c). There is
obtained S98.16= 35.2 0.9, of which 6.75 is extrapolation below 56.20
Basic Sulfates.-From consideration of various equilibrium data,
the author (273) has calculated AS98.16= -3.5 for the reaction
PbSO4(c) +PbO(c) =PbSO4.PbO(c), AS29S8.1= -4.3 for the reaction
PbSO4(c) +2PbO(c) =PbSO4.2PbO(c), and AS29s. = -5.8 for the
reaction PbSO4(c) +3PbO(c)= PbSO4.3PbO(c). These values lead to
S8s.16= 48 2 for PbSO4-PbO(c), S98s.6=64 2.5 for PbSO4.2PbO(c),
and S9s.16= 79 3 for PbSO4.3PbO.
Telluride.-McAteer and Seltz (347) reported ASs98.1 = -1.0 for
the reaction Pb(c)+Te(c)=PbTe(c). This leads to S98.1-6=26.4t
0.7 for PbTe(c).
For PbTe(g), there is estimated here S29s.16= 68.60.5.
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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/m1/63/: accessed April 26, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.