Contributions to the Data on Theoretical Metallurgy: [Part] 11. Entropies of Inorganic Substances: Revision (1948) of Data and Methods of Calculation Page: 20
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20 CONTRIBUTIONS TO DATA ON THEORETICAL METALLURGY
and Hollnagel (404) have given v =63.4X10-4 cm. as the mean
residual-ray wave length. Dividing the velocity of light by this figure
63.4103X104) gives v=4.73X 1012 as the mean frequency. This
frequency is considered to be that associated with the Einstein func-
tion, in accordance with the previously mentioned theory of Born and
von Karman. The characteristic temperature is OE= k = 227. From
an approximate expression, OE- 1.35 0D, given by Rodebush (480),
OD 168 is evaluated. The calculation from this point is the same as
if, for the specific heat of KC1, C,= D 168)E (227 At 298.160
2 0.563 and = 0.761. The corresponding entropy values
taken from available tables are 11.44 and 7.73, respectively. The
sum, 19.17, is the entropy at constant volume. As the difference
S -S is about 0.3 for salts of this type, there may be written
S298.16--19.5 for KC1.
Table 6 gives in column 2 entropy values obtained by this method
that may be compared with results from low-temperature specific-
heat data in column 3. Except for T1Cl and HgC1, reasonable
agreement is observed.
TABLE 6.-Entropies of salts at 298.160 K.
S48s.16 Si8s.1a Sos .ie S e8.1o
Substance (residual (specific Substance (residual (specific
rays) heats) rays) heats)
NaCL____ ... - -- -- 17. 2 17. 31=0. 3 AgBr- - - -_ 26. 1 25. 60+=0. 10
KCIL _ 19. 5 19. 76=t .07 EgCl------------------ 24.7 23.0 =. 7
KBr ------------___ .- - 22. 6 22. 4 =1.0 T1C1------------------ 23. 7 25. 9 =.6
AgCl -------------------- 22.4 23. 00= .10
ENTROPIES OF INORGANIC SUBSTANCES AT 298.160K.
In the following pages entropy values are given for the elements,
ions, and compounds, based upon the various available data. The
elements are considered in alphabetical order, and the compounds
usually are classified according to their more electropositive constit-
uents. All selected entropy values are for a constant pressure of
1 atmosphere and a temperature of 298.160 K. (25.000C.) and are
expressed in defined calories (1 calorie=4.1833 int. joules) per degree
per gram formula mass.
All temperatures are in degree Kelvin. The symbols (c), (1), and
(g) refer, respectively, to the crystalline, liquid, and gaseous states.
Glasses are denoted by the symbol (gl.). The symbol (aq.) following
ionic formulas denotes a hypothetical, perfect solution of 1 molal
The attempt is made to estimate the accuracy of each selected
entropy result, but in many instances the estimate is largely a matter
of judgment. For values obtained from heat-capacity measurements,
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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/m1/24/: accessed April 20, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.