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Showing 1 to 20 of 25 for “"rates of reaction."”.
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Relative rates of reaction of pyrite and marcasite with ferric iron at low pH
The relative reactivities of pulverized samples (100-200 mesh) of 3 marcasite and 7 pyrite specimens from various sources were determined at 25°C and pH = 2.0 in ferric chloride solutions with initial ferric iron concentrations of 10⁻³ molal. The rate of the reaction: FeS₂ + 14Fe³⁺ + 8H₂O = 15Fe²⁺ …
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Rates of reaction of covellite and blaubleibender covellite with ferric iron at ph 2.0
The rates of reaction of pulverized samples (100-200 mesh) of blaubleibender covellite and covellite with 10⁻³ m ferric iron in a pH 2 solution were determined at 25, 35, and 50°C. Ferrous and cupric ion concentrations of the run solutions suggest that parallel reactions oxidized the sulfur to …
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The chemical effects of ultrasound
The use of high intensity ultrasound to enhance the reactivity of heterogeneous, liquid-solid reactions has become a routine synthetic technique. Typically, ultrasound reduces reaction temperatures and increases rates of reaction while improving product yields. In spite of this, our understanding …
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Part One: Photochemistry of Aryl Azides. Chemical Properties of the Transient Intermediates. Part Two: Thermolysis of an Endoperoxide. Generation of an O-Xylylene Peroxide (Nitrene)
One. The photochemistry of phenyl azide, 1-naphthyl azide, 2-naphthyl azide, 1-anthryl azide, 2-anthryl azide, 1-pyrene azide, and 2-pyrene azide was examined by laser flash photolysis inert and reactive solvents. The products of direct photolysis of the aryl azides can depend dramatically on the …
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Rates of acidic hydrolysis of triptych boroxazolidines
Upon looking at the results of calculation of the rate constants given in Table 2, there are revealed some general trends as to the influence of the substituent groups on the values of the rate constants. If the rate constants of the reaction are considered at a fixed temperature, the rates of …
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Kinetic Isotope Effect of the Oxidative Addition Reaction of Hydrogen to Vaska's Compound
The rates of reaction for the oxidative addition of hydrogen and deuterium gas to Ir(CO)Cl{P(C(,6)H(,5))(,3)}(,2) (Vaska's compound) have been accurately measured over the temperature range 0-50(DEGREES)C in toluene. The kinetic isotope effect, i.e., the ratio of the rate constants …
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Etching of Gallium Arsenide with atomic hydrogen
… method is used to make in-situ observations of continuous etching of the (100) GaAs surface during exposure to a known concentration of thermalised hydrogen atoms downstream from an H₂ plasma. Etch rates between 3 and 9 nm/min are followed at constant temperature within the range 229 - 360 …
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On the reactions of ortho-positronium and inhibition of positronium formation
A study of the interactions of ortho-positronium with a variety of inorganic and organic compounds was undertaken to investigate the mechanisms of the thermal reactions of ortho-positronium and to investigate the processes which inhibit positronium formation. It was found that the rate constants …
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Geochemistry of fluid-rock processes
… with the surrounding rocks, small aliquots of these fluids are trapped as imperfections in the crystal lattice and fractures of minerals. These microscopic features are called fluid and melt inclusions, and are one of the best tools available to probe, measure and determine the chemical and …
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REACTION AND MIGRATION OP SODIUM IN THE SYSTEM SODIUM OXYGEN ~ ALUMINA
A number of investigations have been made Into the reactlon/dlffusion of Na, Na20/Na mixtures, NaOH, Na20 and Na/TiOg mixtures with single crystals, and sintered polycrystalline alumina in the temperature range 973K-1758K. No observable diffusion or reaction was observed for sodium metal in the …
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Development of experimental and instrumental systems to study biological systems
<p>Chapters 1-4 of this thesis describes the development of an experimental system to measure diffusion-limited reaction kinetics in a biological environment. About 100 years ago, the relationship between reaction rate and diffusion in homogenous solution, ie water or buffer, was described as a …
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Deoxidation studies : The interaction of vitreous silica with molten aluminium and systems of aluminium, manganese, iron and silicon.
The interaction of aluminium with silica and silicates isthermodynamically inevitable and leads to reaction effects in many systems. The resultant reactions can continue over a wide temperature range including both liquid and solid state systems such as molten aluminium handling units and the heat …
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Getting to the Point: Bridging the Gap between Simple and Complex Catalytic Systems using Temporal Analysis of Products (TAP)
One of the key issues in the field of catalysis is to relate the catalyst structure/composition to its activity/selectivity. One way to understand this relationship is to understand the individual role each catalyst component plays in the chemical reaction. Industrial catalysts can be extremely …
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The ultra-selective hydrogenation of Furfural on PtCu supported bimetallic nanoparticles and on Pt(111) under ultra-high vacuum
The selective transformation of furfural, a biomass platform molecule, was studied on Pt based heterogeneous catalysts and model single crystal surfaces. Hydrogenation reactions were carried out at pressures ranging from ultra-high vacuum to 20 bar. Temperature Programmed Desorption data in …
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Kinetics reactions of Ammonium Nitrate-Sodium Nitrite Reaction and Ammonium Nitrate Emulsion Explosives
The aim of this study was to understand and control the gasification rates in ammonium nitrate emulsion explosive using ammonium nitrate-sodium nitrite reaction. This reaction produces N2 gas which is the sensitizer in emulsion explosives. The NH4NO3-NaNO2 gassing reaction produces N2 gas and so …
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THE STRUCTURE AND REACTIVITY OF SOME METALLURGICAL CARBONS
The reactivity and micro-structure of three coals and two cokes used in iron and steel manufacture have been studied by a variety of techniques, including gas sorption analysis, thermal analysis and microscopy. Changes in surface areas and porosities of the coals and cokes during combustion have …
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Towards sustainable heterogenous catalysis in molecular solar thermal energy storage (MOST) systems
… doctoral thesis focuses on triggering the back-reaction in MOlecular Solar Thermal (MOST) energy storage systems using heterogenous catalysts. The MOST system consists of a pair of organic switchable molecules which can capture solar radiation, can store the energy within its chemical bonds and …
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Characterization of structure and enzymic activity of endo-l, 4-β-D-glucanases purified from Trichoderma viride
… gel electrophoresis, slab gel eletrophoresis of sodium dodecyl sulfate-protein complexes and ultracentrifugation studies. With CM-cellulose as substrate Endoglucanases II, III and IV have specific viscosimetric activities of 1010, 60 and 250 specific fluidity change minute⁻¹ mg protein⁻¹, …
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Kinetic studies of redox and related reactions of some new isoalloxazines
This thesis describes the synthesis of three new isoalloxazines with special structural characteristics which we hoped would, and in fact did, modify their chemical reactivity so as to improve our understanding of mechanisms of flavin reactions generally: kinetic studies of their reactions with a …
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Application of low PO2 iron-based oxides for decarbonising steel industry via chemical looping
This dissertation exploits the use of low oxygen partial pressure (P<sub>O<sub>2 </sub></sub>) of dicalcium ferrite (Ca<sub>2</sub>Fe<sub>2</sub>O<sub>5</sub>, C<sub>2</sub>F) in multiple applications for decarbonising the hard-to-decarbonise steel industry. Here, C<sub>2</sub>F) is proven to be a …
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