Transition from internal to external oxidation in indium–silver alloys

1968 ◽  
Vol 46 (8) ◽  
pp. 1187-1196 ◽  
Author(s):  
L. D. Pethe ◽  
H. B. Mathur ◽  
A. B. Biswas
Keyword(s):  
Cross Sections ◽  
Absolute Temperature ◽  
Kcal Mole ◽  
Kinetics Of Oxidation ◽  
External Oxidation ◽  
Parabolic Oxidation ◽  
Parabolic Oxidation Rate ◽  
Straight Lines ◽  
Kinetics Of ◽  
Rate Controlling Step

The kinetics of oxidation of In–Ag alloys of 5,10, and 15 at. % indium have been studied on a vacuum microbalance. The 15 at. % indium alloy oxidizes externally and the 5 at. % alloy internally. A plot of logarithm of the parabolic oxidation rate, kp, versus reciprocal of the absolute temperature for 10 at. % indium alloy gives two intersecting straight lines corresponding to the energies of activation of 23 and 39.6 kcal/mole for the oxidation below and above 600 °C respectively. These are comparable to the energies of activation of 23 kcal/mole for the internal oxidation of 5 at. % indium alloy and 40 kcal/mole for the external oxidation of 15 at. % indium alloy. The rate–controlling step in the external oxidation of 15 at. % indium alloy is the diffusion of indium through the alloy. Photomicrographs of the cross sections of the oxidized foils of these alloys confirm the conclusions derived from the kinetic data.

KINETICS OF THE OXIDATION OF URANIUM (IV) BY IRON (III) IN AQUEOUS SOLUTIONS OF PERCHLORIC ACID

1955 ◽  
Vol 33 (12) ◽  
pp. 1780-1791 ◽  
Author(s):  
R. H. Betts
Keyword(s):  
Electron Transfer ◽  
Ionic Strength ◽  
Aqueous Solutions ◽  
Perchloric Acid ◽  
Rate Constants ◽  
Kcal Mole ◽  
Kinetics Of Oxidation ◽  
Temperature Coefficients ◽  
Kinetics Of ◽  
Rate Controlling Step

The kinetics of oxidation of uranium (IV) by iron (III) in aqueous solutions of perchloric acid have been investigated at four temperatures between 3.1 °C. and 24.8 °C. The reaction was followed by measurement of the amount of ferrous ion formed. For the conditions (H+) = 0.1–1.0 M, ionic strength = 1.02, (FeIII) = 10−4–10−5 M, and (UIV) = 10−4–10−5 M, the observed rate law is d(Fe2+)/dt = −2d(UIV)/dt[Formula: see text]K1 and K2 are the first hydrolysis constants for Fe3+ and U4+, respectively, and K′ and K″ are pseudo rate constants. At 24.8 °C., K′ = 2.98 sec.−1, and K″ = 10.6 mole liter−1 sec−1. The corresponding temperature coefficients are ΔH′ = 22.5 kcal./mole and ΔH″ = 24.2 kcal./mole. The kinetics of the process are consistent with a mechanism which involves, as a rate-controlling step, electron transfer between hydrolyzed ions.

Oxidations involving silver. I. Kinetics of the anodic oxidation of silver in alkaline electrolytes

1968 ◽  
Vol 46 (22) ◽  
pp. 3437-3442 ◽  
Author(s):  
T. G. Clarke ◽  
N. A. Hampson ◽  
J. B. Lee ◽  
J. R. Morley ◽  
B. Scanlon
Keyword(s):  
Electrochemical Oxidation ◽  
Anodic Oxidation ◽  
Kcal Mole ◽  
Kinetics Of Oxidation ◽  
Ion Concentrations ◽  
Enthalpy Of Activation ◽  
Hydroxyl Ion ◽  
Different Temperatures ◽  
Alkaline Electrolytes ◽  
Kinetics Of

The kinetics of the electrochemical oxidation of silver to Ag2O in NaOH have been studied at different temperatures and hydroxyl ion concentrations. The enthalpy of activation was found to be ~ 5 kcal/mole. The kinetics of oxidation of Ag2O to AgO are discussed.

Kinetics and mechanisms of oxidations by metal ions. Part VI. Oxidation of α-hydroxy acids by cerium(IV) in aqueous nitric acid

1986 ◽  
Vol 64 (1) ◽  
pp. 19-23 ◽  
Author(s):  
Narain Datt ◽  
Ratan R. Nagori ◽  
Raj N. Mehrotra
Keyword(s):  
Nitric Acid ◽  
Hydroxy Acid ◽  
Activation Parameters ◽  
Order Rate Constant ◽  
Acid Complex ◽  
Kinetics Of Oxidation ◽  
Activated State ◽  
Kinetics Of ◽  
Cerium Iv Ammonium Nitrate ◽  
Rate Controlling Step

The kinetics of oxidation of glycolic, malic, tartaric, and citric acids by cerium(IV) ammonium nitrate were investigated in 0.006 mol dm−3 nitric acid. The reaction was catalysed by H+ in the range 0.006–0.016 mol dm−3 at constant [Formula: see text] (0.02 mol dm−3). The pseudo first-order rate constant kobs was independent of [CeIII] (0.0004–0.002 mol dm−3). The proposed mechanism is based on the assumption that the formation of the precursor Ce(IV) – α-hydroxy acid complex precedes its rate controlling disproportionation, which is assisted by a proton, possibly due to the formation of the activated state [H+—CeIV – HA]≠ (where CeIV is the reactive cerium(IV) species and HA is the α-hydroxy acid). The free radical R1R2ĊOH produced in the rate controlling step further reacts with a number of Ce(IV) molecules in the fast step to yield the final oxidation product. The activation parameters for the rate controlling step could be evaluated only in the oxidation of tartaric acid.

The kinetics of oxidation of benzaldehyde. II. The kinetics of the uncatalyzed reaction in solution

1953 ◽  
Vol 216 (1124) ◽  
pp. 30-44 ◽  
Keyword(s):  
Arrhenius Equation ◽  
Initial Rate ◽  
Benzene Solution ◽  
Kcal Mole ◽  
Widespread Occurrence ◽  
Kinetics Of Oxidation ◽  
Kinetic Behaviour ◽  
Uncatalyzed Reaction ◽  
Kinetics Of ◽  
Reaction In Solution

The initial rate of oxidation of benzaldehyde in benzene solution in the absence of catalysts and inhibitors is given by the relation (-d[O 2 ]/d t ) = ([ R H] 2 [O 2 ])/( b [ R H] 2 + c [O 2 ]). The reciprocals of the constants b and c vary with temperature according to the Arrhenius equation, the corresponding activation energies being 6.0 ± 0.5 and 17.5 ± 1.0 kcal/mole respectively. The difficulty of interpreting the relation in terms of the mechanism proposed by Bolland & Gee (1946) for photochemical and peroxide catalyzed oxidations is pointed out. It is suggested that this kinetic behaviour is of widespread occurrence in uncatalyzed oxidations.

The effect of the reactions at the scale-gas and scale-metal. Interfaces on the kinetics of oxidation of pure metals

1995 ◽  
Vol 92 (12) ◽  
pp. 1315-1330 ◽  
Author(s):  
F. Gesmundo ◽  
J. Philibert ◽  
Y. Niu
Keyword(s):  
Kinetics Of Oxidation ◽  
Pure Metals ◽  
Metal Interfaces ◽  
Kinetics Of

Spectrocoulometry – a new spectro-electrochemical technique

1987 ◽  
Vol 52 (6) ◽  
pp. 1386-1396 ◽  
Author(s):  
Ján Mocák ◽  
Michal Németh ◽  
Mieczyslaw Lapkowski ◽  
Jerzy W. Strojek
Keyword(s):  
Optical Probe ◽  
Optical Signal ◽  
Open Circuit ◽  
Electrochemical Technique ◽  
Kinetics Of Oxidation ◽  
Hydrolytic Reaction ◽  
Experimental Errors ◽  
Mechanism And Kinetics ◽  
Kinetics Of

A spectrocoulometric macrocell with a direct-view optical probe was designed and constructed, where the optical signal is transferred by light-conducting glass or quartz fibres permitting to work at wavelengths above 410 or 300 nm. The method of measurement on the proposed equipment is described; it was tested in the study of the mechanism and kinetics of oxidation of Fe(bipy)32+ ions (bipy = 2,2'-bipyridyl) with the use of potentiostatic coulometric electrolysis with open-circuit relaxation at a suitable time. The primary product of electrolysis, Fe(bipy)33+, undergoes a follow-up hydrolytic reaction with the formation of a binuclear complex. The rate constant of the reaction of the first order involves the contributions, kBi, from all bases present in solution; the corresponding values for H2O, OH-, bipy, and CH3COO- ions at a ionic strength 0·5 mol dm-3 and 25 °C were determined as kOH = (5·0 ± 0·6) . 105 mol-1 dm3 s-1, kbipy = (1·3 ± 0·2) . 10-1 mol-1 dm3 s-1, kAc = (5·8 ± 1·0) . 10-2 mol-1 dm3 s-1, and kH2O is not significant with respect to experimental errors.

Effects of salts on the kinetics of oxidation of alkenes by thallic salts in aqueous solutions

1981 ◽  
Vol 46 (3) ◽  
pp. 693-700 ◽  
Author(s):  
Milan Strašák ◽  
Jaroslav Majer
Keyword(s):  
Aqueous Solutions ◽  
Phase Transfer ◽  
Heterogeneous Reaction ◽  
Qualitative Model ◽  
Kinetic Effect ◽  
Tetraalkylammonium Salts ◽  
Reaction Conditions ◽  
Kinetics Of Oxidation ◽  
Kinetics Of ◽  
Heterogeneous Reaction Conditions

The kinetics of oxidation of alkenes by thallic sulphate in aqueous solutions, involving the two reaction steps-the hydroxythallation and the dethallation - was studied, and the effect of salts on the kinetics was examined; this made it possible to specify more precisely the reaction mechanism and to suggest a qualitative model of the reaction coordinate. It was found that in homogeneous as well as in heterogeneous reaction conditions, the reaction can be accelerated appreciably by adding tetraalkylammonium salts. These salts not only operate as catalysts of the phase transfer, but also exert a significant kinetic effect, which can be explained with a simplification in terms of a stabilization of the transition state of the reaction.

Kinetics of oxidation of ammonia on cobalt catalyst I model of the reactor with catalytically active wall

1982 ◽  
Vol 47 (8) ◽  
pp. 2087-2096 ◽  
Author(s):  
Bohumil Bernauer ◽  
Antonín Šimeček ◽  
Jan Vosolsobě
Keyword(s):  
Parabolic Equations ◽  
Cobalt Catalyst ◽  
Nonlinear Parabolic Equations ◽  
Catalytic Reactions ◽  
Temperature Profiles ◽  
Dimensional Model ◽  
Kinetics Of Oxidation ◽  
Nonlinear Parabolic ◽  
Catalytically Active ◽  
Kinetics Of

A two dimensional model of a tabular reactor with the catalytically active wall has been proposed in which several exothermic catalytic reactions take place. The derived dimensionless equations enable evaluation of concentration and temperature profiles on the surface of the active component. The resulting nonlinear parabolic equations have been solved by the method of orthogonal collocations.

Thermodynamic and Kinetic Investigation of the Solvent Effect on the Oxidation of [Co(en)2SCH2COO]+ with S2O82- In Water-Methanol and Water-tert-Butyl Alcohol Mixtures

1993 ◽  
Vol 58 (5) ◽  
pp. 1001-1006 ◽  
Author(s):  
Oľga Vollárová ◽  
Ján Benko
Keyword(s):  
Transfer Functions ◽  
Activation Parameters ◽  
Butyl Alcohol ◽  
Oxidation Of Co ◽  
Kinetics Of Oxidation ◽  
Tert Butyl ◽  
Tert Butyl Alcohol ◽  
Alcohol Mixtures ◽  
Kinetics Of

The kinetics of oxidation of [Co(en)2SCH2COO]+ with S2O82- was studied in water-methanol and water-tert-butyl alcohol mixtures. Changes in the reaction activation parameters ∆H≠ and ∆S≠ with varying concentration of the co-solvent depend on the kind of the latter, which points to a significant role of salvation effects. The solvation effect on the reaction is discussed based on a comparison of the transfer functions ∆Ht0, ∆St0 and ∆Gt0 for the initial and transition states with the changes in the activation parameters accompanying changes in the CO-solvent concentration. The transfer enthalpies of the reactant were obtained from calorimetric measurements.

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