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★ ★ tyding(金币+2,VIP+0):xiexie
Your are right. It depends on decomposition conditions.
1. The thermal decomposition of platinum disulfide, platinum monosulfide and cupric sulfide. Biltz, Wilhelm; Juza, Robert. Z. anorg. allgem. Chem. (1930), 190(No. 112), 161-77. Journal language unavailable.
Abstract
The thermal decompn. of PtS2 PtS and CuS was measured by means of a quartz spiral manometer. A "sulfur valve" was devised to seal the app. by allowing a droplet of S to solidify in a capillary tube. Graphs indicate the following decompn. pressures: For PtS2: 55 mm. at 616°, 120 mm. at 657° , 354 mm. at 691°; for PtS: 55 mm. at 1060°, 115 mm. at 1110°, 330 mm. at 1186°; for CuS: 100 mm. at 460°; 220 mm. at 474°. At temps. above 660°, CuS is completely decompd. into Cu2S and S2. From these data, the following heats of formation are calcd.: Pt + S (rhombic) ® PtS + 16,000 cals.; PtS + S ® PtS2 + 5000 cals.; 2Cu2S+ S2) ® 4CuS + 38,000 cals. These values indicate that the Pt sulfides are more stable than is generally supposed, more stable even than HgS and Ag2S.
2. Thermal decomposition of CuS to Cu1.8S. Shah, Ishwarlal D.; Khalafalla, Sanaa E. Twin Cities Metall. Res. Cent., Bur. Mines, Minneapolis, MN, USA. Metallurgical Transactions (1971), 2(2), 605-6. CODEN: MTGTBF ISSN: 0026-086X. Journal written in English.
Abstract
When covellite (CuS) was heated in flowing N the reaction is 1.8 CuS ® Cu1.8S + 0.8 S. The data are plotted. From the slopes of the plots the apparent activation energy is 24 ± 2 kcal. In the absence of gas diffusion control, the thermal decompn. of Cu1.8S at 345-400° depends on the initial surface area of the CuS pellet rather than on the receding interface as reported by M. M. Pavlyuchenko and G. I. Saml (1964). |
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