Contributions to the Data on Theoretical Metallurgy: [Part] 11. Entropies of Inorganic Substances: Revision (1948) of Data and Methods of Calculation Page: 41
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ENTROPIES OF INORGANIC SUBSTANCES AT 298.160K.
(364) and quantum weights of 4 and 2, respectively. The entropy
associated with these states is 2.830 units, and the translational
entropy is 36.634. The sum is S98.1= 39.460.01 for Cl(g).
Chloride Ion.-From thermal data for the reactions HCI(g)=
H+(aq.) +C1- (aq.) and AgCl(c)+ H2(g)=H+(aq.) +Cl-(aq.) +Ag(c),
Latimer, Pitzer, and Smith (325) obtained, respectively, 13.52 + 0.15
and 13.49 +0.15 as values of the entropy of Cl-(aq.). The value
Ss8.16= 13.5 0.1 is adopted. This figure has been checked by Rossini
(402), who obtained S298.16= 13.40 0.15 for HCl(aq.) at hypothetical
1 molal concentration. Since by convention S298.16-=0 for H+(aq.), it
follows that 13.400.15 is also the entropy of Cl-(aq.).
Monoxide.-Sutherland and Penney (479) have reported C1-0 dis-
tance=1.71X 10-8 cm., C1-O-C1 angle= 1100, 1=680(1), 02--320(1),
and C3=973(1) for C120(g). There are computed 11=252X10-40,
I2=231 X 10-40, and 13=20.8 X 10-40, which in turn give St+r,298.16-
61.94. The vibrational entropy is S,298.16= 1.74. The sum is S98.18-
Yost and Felt (509) obtained heat and free-energy-of-formation
values for C120(g) which yield AS298.16= -9.9 as the entropy of forma-
tion. This value leads to S298.16= 67.9, which can be given no weight
in comparison with the figure from the molecular constants.
Dioxide.-Brockway (55) has reported 1.53X10-8 cm. as the C1-0
distance and 1370 as the O-C1-0 angle in the CIO2(g) molecule. These
figures lead to 1=116.5X10-40 I2=107.7X10-4, and 13=8.8X10-40
and to So+r,298.18= 58.79. According to Ku (307) the vibration fre-
quencies are 529(1), 954(1), and 1,105(1), giving S1,298.18=0.76. The
sum is S98.16= 59.6 0.5 for C102(g).
Fluoride.-The entropy of C1F(g) is estimated from the relationship
So. (CIF(g))=Y2 S8.16 (c2()+ 98.16 (F2(g))+R In 2 to be
S2098.16 = 52.3 0.5.
Hypochlorite Ion.-Latimer, Pitzer, and Smith (325) reported
S298.16= 10.02.0 for C10-(aq.) from thermal data for the reaction
C12(g) +20H-(aq.) = H1120(l) C1- (aq.) + C10- (aq.).
Chlorite Ion.-Latimer, Pitzer, and Smith (325) also reported S98,.1
=24.1 0.5 for C1202 (aq.), from thermal data for the reaction AgCIO2
(c) = Ag+(aq.) + C102- (aq.).
Chlorate Ion.-The value S298.=6--39.40.5 for C103-(aq.) was ob-
tained by Latimer, Pitzer, and Smith (325) from thermal data for
the reaction KCI03(c)= K-(aq.) +C103 (aq.).
Perchlorate Ion.-In addition, Latimer, Pitzer, and Smith (325)
have given S298.16=43.6 0.5 for C104-(aq.), based upon thermal data
for the reaction KC104(c)= K+(aq.)+ClO- (aq.).
Element.-The heat capacity of Cr(c) was measured by Anderson
(22) (560-2920) and Simon and Ruhemann (441) (710-790). The data
of the former give S298.16= 5.68 0.07, of which 0.22 is extrapolation
The spectroscopic data on Cr(g) show that only the lowest energy
state, 7S3, must be considered at 298.160 in deriving the entropy.
This state adds R In 7 to the Sackur equation to give S29s.1=41.64
0.01 for Cr(g).
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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/m1/45/: accessed April 26, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.