Contributions to the Data on Theoretical Metallurgy: [Part] 11. Entropies of Inorganic Substances: Revision (1948) of Data and Methods of Calculation Page: 31
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ENTROPIES OF INORGANIC SUBSTANCES AT 298.160K.
Iodides.-The only available value for CdI2(c) is that given by
Bates (40), S29s,18= 39.5, in which the error is estimated as + 2.0.
Molecular-constant data estimated by Stevenson (467) yield
S298,1= 65.0 0.5 for CdI(g).
Sulfates.-From consideration of the thermodynamic properties of
CdSO4(c), Kelley (273) has computed S,s8,= 31.3, in which the error
may be a few units. He also estimated S2, =39.7 for CdSO4.H20(c)
and S298,18=57.5 for CdSO4.8/3H20(c).
Sulfide.-Kelley (273), in considering the thermodynamic properties
of CdS(c), has estimated S28s,s1= 171.
Telluride.-McAteer and Seltz (347) have obtained AS98,16= -2.0
for the formation of CdTe(c) from the elements. This result leads to
S298,18=22.2 1.0 for CdTe(c).
Antimonides.-The reaction Cd(l)+Sb(c)=CdSb(c) was studied
by Seltz and De Haven (415). They obtained AH= -4,730 (AC,
assumed zero) and AF=87= -2,559. From these figures, AF=
-4,730+3.16T, which at the melting point of Cd, 5940, yields
AF~94= -2,853. Taking the heat of fusion of Cd as AH594=1,450
(288), there is obtained AF= -3,280 + 0.72 T for the reaction Cd(c) +
Sb(c)= CdSb(c). The entropy of reaction is therefore -0.72, which
results in S298,1= 22.1+ 1.0 for CdSb(c).
Seltz and DeWitt (416) have obtained AS298,16=21.0 for the reaction
3Cd(c)+2Sb(c)=Cd3Sb2(c). This figure leads to S298,16= 79.05 for
Element.-The low-temperature heat capacity of Ca(c) was meas-
ured by Clusius and Vaughen (105) (100-2010), Eastman and Rode-
bush (139) (670-2940), and Giinther (204) (220-620). Relying
almost entirely on the data of Clusius and Vaughen, there are ob-
tained S .0= 0.013 (extrapolation), Sg8s.16-o 0.0= 9.94, and Sos8.16
Spectroscopic data for Ca(g) (364) show that only the lowest energy
level, of unit quantum weight, need be considered in obtaining S29s.16
=37.00+0.01 from the Sackur equation.
Calcium Ion.--Latimer, Pitzer, and Smith (325) have obtained
S298.16= -11.4 + 0.3 for Ca++(aq.) from thermal data for the reac-
tion CaCO3(c) + 2H+ (aq.) = Ca++(aq.) + H20 (1) + CO2 (g).
Oxide.-Nernst and Schwers (377) (280-900) and Parks and
Kelley (383) (870-2930) have measured the heat capacity of CaO(c).
The resulting entropy values are S2s.0=0.04 (extrapolation), S298.18-
S28.0= 9.46 (measured), and S298.16= 9.5 + 0.2.
The values, I=57.2X 10-40 (311) and w=837 (212), are available
for CaO (g). There are computed S+,298.16= 52.11 and S,29s.16=
0.18, making S29s.16= 52.3 + 0.3.
Borates.-Low-temperature heat-capacity measurements of four
crystalline calcium borates were reported by Kelley, Todd, and
Shomate (299) (3CaO.B203, 520-2970; 2CaO.B203, 530-2970; CaO.-
B203, 54o-2970; and CaO-2B203, 540-2970).
For 3CaO.B203 (c), the entropy extrapolation below 52.000 is 2.16,
and the measured portion from 52.000 to 298.160 is 41.73, making
S298.16 = 43.9 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/m1/35/: accessed April 19, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.