Contributions to the Data on Theoretical Metallurgy: [Part] 11. Entropies of Inorganic Substances: Revision (1948) of Data and Methods of Calculation Page: 45
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ENTROPIES OF INORGANIC SUBSTANCES AT 298.16K.
Sulfates.-From calculations of the author (273), the following
values were suggested: S98.16=25.3 for CuSO4(c), S98s. 1=34.1 for
CuO-CuSO4(c), S29.16=33.0 for CuSO4.H20(c), SI98.18=52.4 for
CuSO4.3H20(c), and S2,9.1,=70.2 for CuSO4-5H20 (c). No attempt is
made to estimate the uncertainties in these figures.
Sulfate.-Long and Degraff (338) measured the heat capacity of
Eu2 (S04)3-8H20 (c). At the lowest point of the measured temper-
ature range the heat capacity is 36.44 cal. per deg. per mole, which
makes the calculation of the entropy difficult and somewhat uncertain.
However, there is estimated S0.0= 19.2 as the extrapolated portion
of the entropy, not considering unextracted magnetic entropy. The
measured portion is S298.16-S0.0= 133.7. To these quantities must
be added 2R In 7 to account for splitting of the ground state of Eu+++
The total is S29s.16=160.6 1.6 for Eu2 (S04)3.8H20(c).
Element.-Murphy and Vance (368) have computed the entropy of
F2(g) from molecular constants. They give w=856, and the nuclear
separation as 1.45X10-8 cm. The latter corresponds to I= 33.2 X
10-40. There are computed St+7, 298.16=-48.39, S, 298.16= 0.17, and
S298.16=48.560.10. The difference of 0.02 between the last value
and that reported by Murphy and Vance is attributable to differences
in the natural constants employed. A virtually identical result also
was calculated by Garner and Yost (165), S298s. 8=48.6.
Kanda (238) (140840) measured the heat capacities of solid and
liquid F2 and the heat of fusion. His data lead to S5.2= 17.70 for
F2(1) at the normal boiling point. Combination of this result and
the entropy increment for heating the gas from 85.20 to 298.160,
8.90 units, would yield AS85.2=22.0 as the entropy of vaporization
to form ideal gas at 1 atmosphere pressure. The last result is much
higher than is indicated by vapor-pressure data for liquid fluorine.
It is evident that some discrepancy exists in these thermal data.
The value, S898.16=48.560.10, is adopted for F2(g).
In obtaining the entropy of monatomic F(g), two energy states
are concerned at 298.160, 2P /2 and 2P~,2. These states are separated
by 407 cm.-1 (364) and have quantum weights of 4 and 2, respectively.
Calculation gives 3.146 to be added to the Sackur equation. The
result is S9.16=37.92 0.01.
Fluoride Ion.-Latimer, Pitzer, and Smith (325) have obtained the
entropy of F-(aq.) from thermal data for three reactions, HF (g)=
H+(aq.) +F-(aq.), BaF2(c) =Ba++(aq.) +2F-(aq.), and CaF2 ()=
Ca++(aq.)+2F-(aq.). The results, -2.42, -0.42, and
-4.22, respectively, are not in good agreement. The mean is
S98.18= -2.3 2.
Monoxide.-Stuart (476) has given 1.4X10-s cm. and 2.22X10-8
cm., respectively, as the F-O and F-F distances in the F20(g)
molecule and1 105050 as the valence angle. From these figures,
1= 91.2 X 10-40, 12=77.7X 10-40, and 13=13.5X10-40. There is com-
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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/m1/49/: accessed April 18, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.