Contributions to the Data on Theoretical Metallurgy: [Part] 7. The Thermodynamic Properties of Sulphur and its Inorganic Compounds Page: 21
ii, 154 p. : tables ; 24 cm.View a full description of this report.
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THERMODYNAMIC PROPERTIES OF SULPHUR
results of table 19 is well within the limits of error in determining
AE0 or in the heat of formation of H2S from S(rh) and H2 which must
be considered in arriving at the adopted AH0 value. Further reference
to this point may be found in the discussion of the reaction H2+S(rh)
=H2S.
On completing equations (73) and (74), there results
2H2+ S2(g) = 2H2S(g);
AH= -38,810-6.69 T+ 2.065X 10-ST2, (77)
AF= -38,810+ 15.41T log T- 2.065 X 10-3 T2 - 25.02 T, (78)
AH28s.1= -40,620; AF29es.1= -35,085; AS28.l1= -18.57.
Reaction H2+S(rh) =H2S(g).--Zeumer and Roth (175) have deter-
mined AH293.1= -4,800+ 150 as the heat of formation of H2S(g) from
S(rh) and H2. This value may be assigned to 298.10 within the limits
of experimental error. The entropy of formation at 298.10 is AS298.1=
10.28, derived from the values S298.1=31.23 for H2, S298.1=7.64 for
S(rh), and S298.1=49.15 for H2S(g) (70). The necessary information
has been recorded already for obtaining
AC,=--3.05-3.73 T. (79)
On evaluating AHo and I from AH298.1 and AS298.1, there results
H2 + (rh) = H2S(g) ;
AH= -3,725 - 3.05 T- 1.865 X 10-3 T', (80)
AFo= -3,725+7.02 T log T+1.865X10-aT2-31.82 T, (81)
AH298.1= - 4,800; AF8s.1 = - 7,865; AS298.1= 10.28.
Proper combination of equations (77), (78), (80), and (81) gives the
results previously adopted for the reaction 2S(rh)= S2(g). The value
of AHo given above for the reaction 2H2+S2(g) =2H2S(g) was chosen
so that the results of this combination would be identical with similar
calculations involving the formation of SO2 from S2(g) and 02 and
from S(rh) and 02. As the value for the heat of formation of H2S(g)
is good only to +150 calories, it is seen that the value of AHo adopted
does no violence to the experimental data. It seems preferable to
retain the measured heat-of-formation value and adjust AEo in the
reaction 2H2+S2(g) =2H2S(g) accordingly. This is identical with the
procedure that has been followed here, as the adjustment of AEo0
would have resulted in the AHo value adopted. The reason for pre-
senting the treatment in the manner followed is that it shows how
the values in table 4 were obtained.
Reaction H2S(g)+I2(s) =2HI-{S(rh).-Three determinations of
equilibrium constants of this reaction in the temperature range 3130
to 3340 were made by Pollitzer (122). These data are discussed
because they were mentioned in connection with the reaction
2S(rh)=S2(g) and because they show reasonable agreement with the
results of the last section. As the temperature range covered is small
and near room temperature, a constant AC, will be used in treating
these data. From specific-heat values at 298.10, C,=5.44 for S(rh)
(previously mentioned), C,= 6.954 for HI (theoretical), C,= 13.14 for
I2(s) (70), and C ,=8.12 for H2S(g) (20), AC,=--1.91 is obtained.
From
aH0
2= -R In K-1.91 In T= -R In K-4.40 log T -- +I, (82)21
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Kelley, K. K. Contributions to the Data on Theoretical Metallurgy: [Part] 7. The Thermodynamic Properties of Sulphur and its Inorganic Compounds, report, 1937; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc66396/m1/23/: accessed April 25, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.