OXIDATION OF MANGANATE BY HYPOCHLORITE

1961 ◽  
Vol 39 (1) ◽  
pp. 96-101
Author(s):  
M. W. Lister ◽  
Y. Yoshino
Keyword(s):  
Activation Energy ◽  
Potassium Permanganate ◽  
Rate Constants ◽  
Effective Activation Energy ◽  
Equilibrium Constants ◽  
Intermediate Formation ◽  
Ion Concentration ◽  
Effective Activation ◽  
Text Data ◽  
Hydroxide Ion

The oxidation of potassium manganate to potassium permanganate by potassium hypochlorite has been examined. The rate of the reaction is proportional to the square of the manganate concentration and the first power of the hypochlorite, and it is inversely proportional to the permanganate concentration and to the square of the hydroxide ion concentration. It seems probable that the reaction involves the intermediate formation of hypomanganate ions from a relatively fast disproportionation of manganate, followed by a slower oxidation by hypochlorite. The following mechanism is tentatively proposed:[Formula: see text]Data on the over-all rate and effective activation energy (19.6 kcal/g-molecule) are given; but at present it is not possible to separate all the rate constants and equilibrium constants.

scholarly journals Adsorption and Decomposition of Peroxides on the Surfaces of Dispersed Oxides Fe2O3, Cr2O3 and V2O5

2019 ◽  
Vol 3 (1) ◽  
pp. 13
Author(s):  
Volodymyr Dutka ◽  
Olena Aksimentyeva ◽  
Nataliya Oschapovska ◽  
Yaroslav Kovalskyi ◽  
Halyna Halechko
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Effective Activation Energy ◽  
Equilibrium Constants ◽  
Langmuir Equation ◽  
Effective Activation ◽  
Activation Energy Of Degradation ◽  
Degradation Reaction ◽  
Desorption Equilibrium ◽  
Adsorption Desorption

The adsorption of peroxides on dispersed oxides Fe2O3, Cr2O3 and V2O5 was studied. It is shown that the adsorption of peroxides is described by the Langmuir equation. The adsorption of benzoyl peroxide grows within Fe2O3<Cr2O3<V2O5. Adsorption-desorption equilibrium constants (K) for Cr2O3 and V2O5 are the same, but for Fe2O3 this value is 6 times higher. The decomposition of peroxides is observed in the solution and on the surface of adsorbents. The effective activation energy (E) of the thermal decomposition of peroxides in the studied systems is in the range of 80–140 kJ/mol. The activation energy of degradation of peroxides on the surface (Es) of the dispersed oxides studied is lower. The degradation reaction of peroxides on the surface of Fe2O3 and V2O5 has an oxidation-reducing nature, during which free radicals are produced. On the surface of Cr2O3, there is a heterolytic decay of peroxides. The parameters of the reaction of peroxides decomposition are found. The decomposition of peroxides in the presence of Fe2O3, Cr2O3 and V2O5 in styrene is accompanied by the formation of polystyrene both in the solution and on the surface of the adsorbent.

MAGNETIC RESISTIVITY IN Bi2Sr2Ca(Cu1-xCox)2Od EPITAXIAL THIN FILMS

2007 ◽  
Vol 21 (01) ◽  
pp. 127-132
Author(s):  
T. R. YANG ◽  
G. ILONCA ◽  
V. TOMA ◽  
P. BALINT ◽  
M. BODEA
Keyword(s):  
Magnetic Field ◽  
Thin Films ◽  
Activation Energy ◽  
Glass Transition ◽  
Effective Activation Energy ◽  
Epitaxial Thin Films ◽  
Effective Activation ◽  
High Quality ◽  
Plastic Deformations ◽  
Magnetic Resistivity

The scaling behavior of the effective activation energy of high-quality epitaxial c-oriented Bi 2 Sr 2 Ca ( Cu 1-x Co x)2 O d thin films with 0≤x ≤0.025 has been studied as a function of temperature and magnetic field. For all samples, the effective activation energy scales as U(T, μoH)=Uo(1-T/T c )mHn with exponent m=1.25±0.03, n=-1/2 and the field scaling 1/μoH and -UμoH for thick films and ultra thin films, respectively. The results are discussed taking into account of the influence of the Co substitution with a model in which U(T, H) arises from plastic deformations of the viscous flux liquid above the vortex-glass transition temperature.

Flash photolysis production of the tetrahedral intermediate of the methanolysis of methyl benzoate. Direct measurement of the rate of breakdown of the conjugate base form

1990 ◽  
Vol 68 (3) ◽  
pp. 375-382 ◽  
Author(s):  
Robert A. McClelland ◽  
V. M. Kanagasabapathy ◽  
Steen Steenken
Keyword(s):  
Rate Constants ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Carbonyl Oxygen ◽  
Methyl Benzoate ◽  
Ion Concentration ◽  
Hydroxide Ion ◽  
Tetrahedral Intermediate ◽  
Conjugate Base

Laser flash photolysis in aqueous basic solutions of the ortho acid derivatives 1-(phenyldimethoxymethyl)benzimidazole 2 and 4-bromo-1-(phenyldimethoxymethyl)imidazole 3 results in production of the phenyldimethoxymethyl cation, which has λmax at 260 nm. The cation decays in reactions with water (k = 9.9 × 104 s−1) and hydroxide ion (2.5 × 108 M−1 s−1) to finally yield methyl benzoate, whose formation was monitored at 234 nm. In solutions with pH 10–12, rate constants measured at this wavelength are the same as those obtained at 260 nm, but with pH > 13 and pH < 9, rate constants at 234 nm are smaller. With pH 9–10 and pH 12–13, single exponential kinetics are not observed at 234 nm. This behavior is interpreted in terms of a scheme where at each pH there are two consecutive first-order reactions, cation → phenyldimethoxyhydroxymethane (5) → ester, and the pH dependencies of the rate constants are such that they cross twice over the pH range of this study. The intermediate 5 is the tetrahedral intermediate formed in the methanolysis of methyl benzoate, and the 234-nm buildup at pH > 13 and pH < 9 directly measures its breakdown. At pH > 13 the rate constant is independent of pH with k = 9 × 106 s−1. This represents the rapid expulsion of methoxide from the conjugate base of 5. At pH < 9 the rate constants are proportional to hydroxide ion concentration, with [Formula: see text]. In these solutions the neutral intermediate predominates and the dependence on [OH−] of its rate of conversion to ester is interpreted in terms of breakdown of the anion and protonation of this species by water occurring at comparable rates. Thus, [Formula: see text] represents a situation where there is partial rate-limiting deprotonation of the neutral intermediate by hydroxide. The intermediate of this study bears a close resemblance to the tetrahedral intermediate of the hydrolysis of methyl benzoate. The observation that the anionic forms of such intermediates undergo breakdown at rates similar to those associated with the establishment of proton transfer equilibrium explains why the ester undergoes carbonyl oxygen exchange in base at a rate slower than hydrolysis. Keywords: tetrahedral intermediate, flash photolysis, ester hydrolysis.

Correlation between effective activation energy and pre-exponential factor for diffusion in bulk metallic glasses

1999 ◽  
Vol 14 (8) ◽  
pp. 3200-3203 ◽  
Author(s):  
S. K. Sharma ◽  
F. Faupel
Keyword(s):  
Activation Energy ◽  
Metallic Glasses ◽  
Effective Activation Energy ◽  
Bulk Metallic Glasses ◽  
Supercooled Liquid ◽  
The Novel ◽  
Effective Activation ◽  
Exponential Factor ◽  
Liquid States ◽  
Fitting Parameters

The values of effective activation energy (Q) and pre-exponential factor (D0) reported in the literature for diffusion in the novel bulk metallic glasses, both in the glassy and the deeply supercooled liquid regions, are found to follow the same correlation as reported earlier in conventional metallic glasses, namely D0 = A exp(Q/B), where A and B are fitting parameters with values A = 4.8 × 10−19 m2 s−1 and B = 0.056 eV atom−1. A possible explanation for the observed values of A and B is given by combining an activation energy and a free volume term. The interpretation favors a cooperative mechanism for diffusion in the glassy and deeply supercooled liquid states.

The trans effect in cobalt(III) complexes. Kinetics and mechanism of substitution of cobalt(III) sulphito complexes

1978 ◽  
Vol 31 (3) ◽  
pp. 561 ◽  
Author(s):  
JK Yandell ◽  
LA Tomlins
Keyword(s):  
Ionic Strength ◽  
Water Molecule ◽  
Rate Constants ◽  
Equilibrium Constants ◽  
Ion Concentration ◽  
Nitrite Ion ◽  
Hydrogen Ion Concentration ◽  
Thiocyanate Ion ◽  
Order Rate ◽  
Incoming Ligand

Equilibrium constants K and rate constants kf have been measured, at 25°C and ionic strength of 1.0, for the substitution of the labile water molecule in trans-[aquabis(ethylenediamine)sulphito-cobalt(III)] ion by thiosulphate ion (K = 1.8×102 mol-1 1., kf = 1.27×103 mol-1 1. s-1), thiocyanate ion (2.5×103, 2.75×102), nitrite ion (1.0×103, 2.06×102), azide ion (2.9×102, 2.4×102) ferricyanide ion (-, 1.72×103), hydrogen azide (< 1.2,1.4×10), ammonia (3.0, 6.7) and imidazole (2.6×102, 5.2). ��� The correlation of these rate constants with charge on the incoming ligand, as well as a decrease in the apparent second-order rate constants observed at high concentrations of the anionic ligands, requires a rapid outer-sphere pre-equilibrium step followed by a rate- determining dissociative interchange of the incoming ligand with the bound water molecule. The activation energy of the thiocyanate substitution was found to be 48 kJ mol-1. Aquation of cis- [azidobis(ethylenediamine)-sulphitocobalt(III)] ion, in the range of hydrogen ion concentration between 10-2 and 0.2 M, was found to give the trans-aquasulphito complex with a first-order rate constant consistent with the equation ��������������������������� k = 4.9×10-4[H+]+1.0×10-5 s-1 at 25°C and ionic strength 1.0.

MAGNETORESISTIVITY PROPERTIES AND EFFECTIVE ACTIVATION ENERGY IN YBa2Cu3O7-ρ SUPERCONDUCTING THIN FILM

2006 ◽  
Vol 20 (29) ◽  
pp. 1847-1852
Author(s):  
ALI IHSAN DEMIREL ◽  
SALIM ORAK
Keyword(s):  
Magnetic Field ◽  
Thin Film ◽  
Activation Energy ◽  
Applied Field ◽  
Effective Activation Energy ◽  
Creep Process ◽  
Two Dimensional ◽  
Effective Activation ◽  
Exponential Behavior ◽  
Superconducting Thin Film

The resistive properties and activation energy of YBa 2 Cu 3 O 7-ρ ( YBCO ) superconducting materials change in magnetic field. It is explained that magnetoresistive behavior in terms of the presence of two-dimensional vortices being pinned effectively when they are perpendicular to the CuO 2 planes and an exponential behavior of the activation energy versus the applied field was obtained. The resulting activation energies ranging from 1 to 5 Tesla were attributed to inter-granular flux creep process.

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