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

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CIA-RDP80-00809A000600280214-3
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RIPPUB
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C
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3
Document Creation Date: 
December 22, 2016
Document Release Date: 
September 21, 2011
Sequence Number: 
214
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Publication Date: 
January 20, 1950
Content Type: 
REPORT
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Sanitized Copy Approved for Release 2011/09/22 : CIA-RDP80-00809A000600280214-3 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 1. 1. 0.. Al AMO 07. A) Arl1005. ITS TOAl0lI sll0s OR TH! 010'1001101 OI ITl 0094,191 Il 40T rlllii !O x0 VOAYT000I00A P~AYOY IO AAO 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, SRB~ DATE OF INFORMATION 1949 NO. OF PAGES SUPPLEMENT TO REPORT NO. THIS IS UNEVALUATED INFORMATION CONFIDENTIAL _ D1 RIBUTION I I I ~_ I I I I~ Sanitized Copy Approved for Release 2011/09/22 : CIA-RDP80-00809A000600280214-3 Sanitized Copy Approved for Release 2011/09/22 : CIA-RDP80-00809A000600280214-3 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) Sanitized Copy Approved for Release 2011/09/22 : CIA-RDP80-00809A000600280214-3 Sanitized Copy Approved for Release 2011/09/22 : CIA-RDP80-00809A000600280214-3 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. ^ I U 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 CONFIDENTIAL LOW7S.'a-rn-itized Copy Approved for Release 2011/09/22: CIA-RDP80-00809A000600280214-3 a I U