Contributions to the Data on Theoretical Metallurgy: [Part] 7. The Thermodynamic Properties of Sulphur and its Inorganic Compounds Page: 75
ii, 154 p. : tables ; 24 cm.View a full description of this report.
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THERMODYNAMIC PROPERTIES OF SULPHUR
.75
However, for completeness, both sets of data are considered. The
specific-heat difference and 1-function are
AC,= 6.73- 16.23 X 10-3T- 2.522 X 10 T-2, (422)
and 2=--R In K+15.50 log T-8.12X10- T-1.261X105T-2= A+I. (423)
S P2s2 The calculations are summarized in table 52. 1= -10.64
P ,
is obtained from the entropies at 298.10.
TABLE 52.-CaS04+ S2(g) = CaS + 2SO
T K -RInK 15.50 logT -8.12X10-3T -1.261X10T- 2 Z--I A=Ho
Measurements of Zawadski
1, 173 1. 05X10-2 9. 05 47. 57 -9. 52 -0. 09 47. 01 57. 65 (67, 600)
1, 233 9. 50X10-2 4. 68 47.91 -10. 01 -. 08 42. 50 53. 14 65, 500
1, 253 1.84 X 10-1 3. 36 48. 02 -10. 17 -. 08 41. 13 51. 77 64, 900
1, 273 2. 70X10-1 2. 60 48. 12 -10. 34 -. 08 40. 31 50. 95 64, 900
1,293 3. 29 X 10-1 2.21 48. 23 -10. 50 -. 08 39. 86 50.50 65, 300
1, 313 5. 33X10-1 1.25 48. 33 -10. 66 -. 07 38. 85 49.49 65, 000
1, 333 9. 16X10-1 . 17 48. 43 -10. 82 -. 07 37. 71 48. 35 64, 400
1, 353 -. 36 48.54 -10.99 -. 07 37. 12 47. 76 64, 600
1, 373 -. 70 48.63 -11.15 -. 07 36. 71 47.35 65, 000
1,393 -. 92 48. 73 -11.31 -. 06 36. 44 47. 08 65, 600
Mean 65, 000
Measurements of Schenck and Hammerschmidt
1, 124 6. 30X10-1 0. 92 47. 29 -9. 13 -0. 10 37. 14 47. 78 53, 700
1,170 1. 490 -. 79 47. 56 -9. 50 -. 09 37. 18 47.82 56, 000
1, 228 3. 915 -2. 71 47. 88 -9. 97 -. 08 35. 12 45. 76 56, 200
1, 259 6. 01 -3. 56 48. 05 -10. 22 -. 08 34. 19 44. 83 56, 400
1, 308 11.72 -4. 89 48. 31 -10. 62 -. 07 32. 73 43.37 56, 700
1, 348 17. 59 -5. 70 48. 51 -10. 95 -. 07 31. 79 42. 43 57, 200
Mean 56, 000
If the Ho0-value from Zawadski's data is used, then AH298.1=
-351,230 and AF298.1= -324,380 are obtained for the heat and free
energy of formation of CaSO4. On the other hand, Schenck and
Hammerschmidt's data lead to AH298.1=--342,230 and AF298.1=
-315,380. Although neither set of values deserves much weight, the
results from Schenck and Hammerschmidt's data are much closer to
those obtained by other means.
Another reaction to be considered is the thermal dissociation of
CaSO4, 2CaSO4=2CaO+2S02+02, which was investigated by
Marchal (98) and Zawadski (178). In this case,
AC,= 14.03 - 31.17 X 10-3 T- 4.991 X 105T-2, (424)
2= -Rn K+32.31 log T-15.58X10-ST-2.496X10ST-2= +I, (425)
and K=P2s,.P02. Entropy data (70) yield 1= -48.10.
On calculating the individual AH0 values from Marchal's data, it
was found that a serious trend with the temperature was shown, around
7,400 calories in the 230 temperature range covered by their experi-
ments, and that the mean AH0 did not result in thermodynamic proper-
ties of CaS04 in agreement with those obtained by other methods.
Zawadski, starting with a sample of dehydrated gypsum, observed
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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/m1/77/: accessed April 25, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.