The Dissociation Pressure of Hematite

1969 ◽  
Vol 116 (10) ◽  
pp. 1409 ◽  
Author(s):  
P. E. C. Bryant ◽  
W. W. Smeltzer
Keyword(s):  
Dissociation Pressure

Formation of sodium disulfite in a solid-gas system

1991 ◽  
Vol 56 (8) ◽  
pp. 1575-1579 ◽  
Author(s):  
Jiří Vobiš ◽  
Karel Mocek ◽  
Emerich Erdös
Keyword(s):  
Sodium Sulfite ◽  
Heterogeneous Reaction ◽  
Optimum Conditions ◽  
Kinetic Measurements ◽  
Dissociation Pressure ◽  
Partial Pressures ◽  
Gas System ◽  
Gaseous Sulfur ◽  
Equilibrium Dissociation

The formation of sodium disulfite by the heterogeneous reaction of solid active sodium sulfite with gaseous sulfur dioxide in the presence of water vapour was investigated over the temperature range of 293 to 393 K at SO2. H2O and O2 partial pressures of 1.2-7.4, 1.2-6.4 and 0-11.3 kPa, respectively. The effect of the reaction time was also examined. Kinetic measurements were supplemented with the determination of the equilibrium dissociation pressure of SO2 in contact with sodium sulfite at 373.15 K. The major aim of the work was to establish the optimum conditions for attaining the maximum degree of conversion of the solid reactant to sodium disulfite. The conditions for the formation of virtually pure sodium disulfite were found.

Stabilisation of high dissociation pressure hydrides of formula La1−Ce Ni5 (x=0–0.3) with carbon monoxide

1998 ◽  
Vol 275-277 ◽  
pp. 99-104 ◽  
Author(s):  
Stéphanie Corré ◽  
Mohamed Bououdina ◽  
Daniel Fruchart ◽  
Gin-ya Adachi
Keyword(s):  
Carbon Monoxide ◽  
Dissociation Pressure

Chemical Property of Ground Calcium Carbonate as Carbon Dioxide Absorbent

2010 ◽  
Vol 654-656 ◽  
pp. 2923-2926 ◽  
Author(s):  
Seiji Yokoyama ◽  
Nik Hisyamudin Muhd Nor ◽  
Shunsuke Hirano
Keyword(s):  
Carbon Dioxide ◽  
High Temperature ◽  
Calcium Carbonate ◽  
Physicochemical Properties ◽  
Specific Heat ◽  
Chemical Property ◽  
Emission Rate ◽  
Dissociation Reaction ◽  
Dissociation Pressure ◽  
Ground Calcium Carbonate

Commercial sedimentation CaCO3 was ground by a vibration rod mill to investigate the physicochemical properties of mechanically activated CaCO3.When the CaCO3of the calcite structure was ground, the intensities of the crystal facesof calcite was decreased by distortions and so on, and the aragonite appeared as the grinding proceeded. The formed aragonite was transformed to the calcite when the sample was heated at 773K for3.6 ks. The dissociation pressure of CO2 of the ground CaCO3was larger than that of the non-ground CaCO3.The enthalpy; entropy and specific heat of change of the dissociation reaction were obtained. At high temperature, the emission rate of the ground CaCO3 was slightly larger than that of the non-ground CaCO3. At room temerature, the CaCO3 adsorbs CO2, and it desorbs the adsorbed CO2. The amount of adsorbed CO2 on the ground CaCO3 was larger than that of the non-ground CaCO3.

THE DISSOCIATION PRESSURE OF SILVER OXIDE BELOW 200°

1932 ◽  
Vol 54 (6) ◽  
pp. 2186-2194 ◽  
Author(s):  
Arthur F. Benton ◽  
Leonard C. Drake
Keyword(s):  
Silver Oxide ◽  
Dissociation Pressure

The Effect of CaO Coatings on the Oxidation Behaviour of Polycrystalline Nickel between 800 and 1200 °C

2008 ◽  
Vol 595-598 ◽  
pp. 1075-1081
Author(s):  
N. Halem ◽  
Lukasz Cieniek ◽  
J. Kusinski ◽  
Gianguido Baldinozzi ◽  
C. Petot ◽  
...  
Keyword(s):  
Oxidation Rate ◽  
Depth Profiling ◽  
Decisive Role ◽  
Lattice Diffusion ◽  
Transport Processes ◽  
X Ray Diffraction ◽  
Polycrystalline Nickel ◽  
Dissociation Pressure ◽  
Blocking Effects ◽  
Scale Composition

The present study is concerned with the influence of sputter-coatings CaO on the oxidation behavior of Ni polycrystals. The experiments were performed in air, in the temperature range 800°-1200°C. Below 1200°C, CaO coatings reduce the oxidation rate, while this beneficial effect disappears at 1200 °C. The oxidized specimens were examined by SEM and X-Ray diffraction, but also by EPMA depth profiling to evaluate the scale composition. Furthermore, electrical conductivity measurements and kinetic demixing studies were carried out on Ca-doped NiO single crystals, to get a better insight regarding the transport processes involved during oxidation. These last results show that the key features allowing to explain the effect of CaOcoatings on the oxidation rate of Ni are the influence of calcium on the increase of the dissociation pressure of NiO, which delays the oxidation of nickel, the kinetic demixing of the cations, which controls the distribution of CaO precipitates in the scale responsible for blocking effects, and the increase of the diffusion coefficient of both the cations and the cationic vacancies, which play a decisive role at high temperature, when the scale growth is dominated by lattice diffusion.

Cerium Tetrafluoride. I. Preparation and reactions

1965 ◽  
Vol 18 (7) ◽  
pp. 959 ◽  
Author(s):  
WJ Asker ◽  
AW Wylie
Keyword(s):  
Aqueous Solution ◽  
Water Content ◽  
Water Vapour ◽  
Hydrogen Fluoride ◽  
Low Temperatures ◽  
Cerium Dioxide ◽  
Lattice Parameters ◽  
Refractive Indices ◽  
Dissociation Pressure ◽  
Cerium Trifluoride

Pure anhydrous cerium tetrafluoride is best prepared by fluorinating cerium dioxide at 350-500�. A monohydrate can be obtained from aqueous solution in a variety of ways, but it cannot be dehydrated without decomposition. It loses water "zeolitically" in vacuum, showing relatively small changes in lattice parameters for loss of 70% of its water content. Thereafter the lattice collapses, forming well-crystallized cerium trifluoride and poorly crystallized "anhydrous" cerium tetrafluoride. The refractive indices of anhydrous monoclinic cerium tetrafluoride have been measured and its fluorine dissociation pressure at 500� shown to be less than 0.5 mm. At higher temperatures the tetrafluoride sublimes incongruently, and at 835-841� it melts with extensive decomposition into a fluorine-poor liquid and a fluorine-rich vapour. Cerium tetrafluoride is easily reduced to the trifluoride by ammonia and by water vapour at low temperatures. At higher temperatures it is quantitatively converted by water vapour to cerium dioxide and hydrogen fluoride. When heated with cerium dioxide it is reduced to the trifluoride with liberation of oxygen.

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