VARIATION IN THE FREE ENERGY AND HEAT CONTENT IN REACTIONS LEADING TO THE FORMATION OF COBALT ARSENIDES

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP80-00809A000600280214-3
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 3
• Document Creation Date: December 22, 2016
• Document Release Date: September 21, 2011
• Sequence Number: 214
• Publication Date: January 20, 1950
• Content Type: REPORT

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COUNTRY
I t. CENTRAL INTELLIGENCE AGENCY REPORT
'NFORMATION FROM
.. OREIGN DOCUMENTS OR RADIO BROADCASTS CD NO.
SUBJECT
HOW
PUBLISHED
WHERE
PUBLISHED
DATE
PUBLISHED
LANGUAGE
CLASSIFICATION COHFZDNRTIA.L C014rpr r B
Scleatific - Chemistry
Monthly periodical
Moscow
Sep 1919
Ruseten
41111 FOCLOIOT CG09AAA4 10101rAT10B AIIROT1*; TMl NAno-A- UlffNZ1
Of ToO VIITIO /TATo. YIITWi0 TM1 ^0A0119 or i101ONArl Alt so
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0111010 01
LAW. 011000107100 04 Tlll sore Il RIOIIIl1Tl0.
M. I. Kochuuev, Chair of Metallurgy
of Heavy Nonferrous Metals
Ural Polytech Inst
MIATION IN THE FRKE SNSRGX An EMIT CON F.RT = Fsl1CTIONS
TZADINO TO THE FORMATION OF COBALT ARSSNIDBB
As.a result of reeetrch on the dissociation pressures of cobalt arsenide, (1),
it was found that the dissociation proceeds gradually. The end results of the
dissociation reactions can be sewn from the fo]oving equations (s = solid, g = gas-
eous):
8CoAs2(s) = 4C02As (s)-hAs (g);
kCo2Ae33(e) BCoAs e)~'Ask );
12CoAs(s) = kCo3As2(s) +A4( );
3As2As2(s) ? 8Co5A(.)+A1
20Co 34(g);
2Co5is2(a) = lOCo(s)+As4(g).
Investigation of the dissociation pressures of cobalt ersenides was dictated
by the necessity of studying in detail the oxidation-reduction reactions taking
place in pyrometallizrgy.
Results of determining the dissociation pressures, notwithstanding the obseT-r d
narrow temperature intervals with anoaalous values close to the critical points l1),
demonstrate in several ranges of temperature, a uniformity in their changes; and
also permit the detersdnation of the change in free energy and the heat content re-
sulting from the formation of the compounds.
From a practical point of view, the intervals in temperature during which
the reaecions with tie arsenidee proceed intensively, particularly those during
heating at temperatures close to the temperature of ignition in air end at the
melting point, are of great interest.
Temperatures of ignition of cobalt arsenide, and the dissociation pressures
at temperatures close to then are ss follows:
STAT!
C! Acclrlrervm,
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DATE OF
INFORMATION 1949
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C0I YIDEWTIAI.
Arsenides class 0.1^,y8$0?!)(M
CoAs2 540.
Co2Ae3 61o
CoAs 775
c2 790
Co5Az2 805
3.8 to-3
1.45 10-3
6.97 ? to-5
5.32 io-5
According to research by Preyner and Brokmoler (2), at teffiperatures of 800-
900 degrees centigrade and pressure of 750 millimeters, the molecules of gaseous
arsen4c are 94 percent te,tretomic. With the lowering of the pressure to 10-4
--10-i mss, further dissociation into diatomic molecules occurs; but for the pur-
poses of calculation, it is sufficient to assume that the molecules of gaseous
arsenic in all cases are tetretomic.
Vapor pressures of arsenic gas, deter,ai.:.ied for the dissociation reacts ous
of arsenides, represent constants of equilibrium of the six reactions fr which
the equtions were previously given.
Therefore, the change in free energy (AO, can be detea^tined according to
the equation for the isothena of the reaction A4 = - A - - RT In K and the
change in heat content readily can be determined cording to the equation for
the isobar of the reaction
can be assumed that the veitYPW of arsenic r ,l1 with +he id. 7 ,, o 71 that .~1
t &.modynamic equations for ideal gases apply also to them (6
Sumeary of Results
The higher cobalt arsenide.,;, as well as the monoa.?Jevide, are foetid in nature
in the form of minerals (scutterudite - Coks3; smaltine - CoAs2; and moderite - CoAs)
and also as components of other ores.
The changes in free energy and heat content resulting from the formation of
cobalt arsenide* from the two elements, calculated for 12 gram atoma of cobalt at
740 degrees centigrade and 1014 degrees centigrade (see tables below), increase
in passing from the lower arsenides to the highs .
Table 2. Change in F_-ee Energy and Heat Content through Formation
of Ccbalt Arcanides from the Elements at 740 Centigrade (in calories)
Per 1 Gram Atom Per 1 Gram Atom Pe: 1 4ra:W Atom
Arsenidee of the Cosmnd of Co of As
a0 'All AO aH o0 eH
Co5Aa,2
Co2As
Co3As2
Coke
b02Ae3
CQAs2
-18,765
-41,240
-3,753
-8,248
-9,363
-20,620
-9,336
-20,628
-4,668
-10,31
-9,336
-20,628
-18,345
-41,603
-6,115
-.13,840
-9,173
-20,802
-9,000
-20,790
-9,000
-20,790
-9,000
-20,790
-22,329
-58,248
-11,160
-29,124
-7,443
-19,416
-12,205
-37,580
-12,205
-3T,580
-6,102
-18,790
PA?h (in mm mercury)
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50X1-HUM
of Co of As
AO
?H
6
A H
C05"
-15,108
-36,610
-3,022
-7,322
0a2R.e
-7,678
-18.246
-3,839
-9,132
{'2
-14,578
38,436
-4,859
-12,812
process of formation of several chemical compounds from the two elements can be
obse real.
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3. A. I. Brodsky, "SizlcSesksya khiaiya," Part I, Goekhimizdat, pp 340-343, 19W
4. A. M. Vol'skiy, "Basic Theory of Metallurgical Fusions" (0eavvf teorii metal-
inrgicheskikh plavok), Ne#allurgizdat, 1943
5. M. Kbansen, "Structures of Bi-. try Alloys" (Struktury btnurnykh eplavov) "4l I, 1941
6. N. V. 4udim, " Metallurgy a' " obalt. Handbook of Metallurgy of Nonferrous Metals"
(lletailurgiya koba?t kob&1'ta. Spravochnik metallurgy po tsvetnya motal am),
GNRRI, Vol II, p 428, 1947
Ta. I. Gexasimov and Krestovrilkov, "Chemical Thermocynemica in Nonferrous
Metallurgy" (Khimcheskaya termodi.nrmtka v tevietnoy metallurgti), Vol III, p 213
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