Discreteness-of-charge effects in electrode kinetics. III. The electroreduction of aquopentamminochromium(III) cation in the presence of specifically adsorbed iodide anions

1984 ◽  
Vol 62 (8) ◽  
pp. 1497-1501 ◽  
Author(s):  
W. Ronald Fawcett ◽  
Kveta Markušová
Keyword(s):  
Ionic Strength ◽  
Electrode Kinetics ◽  
Reaction Site ◽  
Charge Effects ◽  
Iodide Concentration ◽  
Rate Acceleration ◽  
Rate Of Reaction ◽  
Layer Effect ◽  
Kinetics Of ◽  
Outer Helmholtz Plane

The kinetics of electroreduction of the aquopentamminochromium(III) cation have been studied at a Hg electrode in acidified aqueous solutions of NaI+ NaClO4 with an ionic strength of 0.25 M. The rate of reaction increased with increase in iodide concentration due to the accelerating effect of this anion when it is adsorbed on the electrode. Analysis of the double layer effect indicates that the rate acceleration is greater than that predicted by the Frumkin theory chiefly because the reaction site is closer to the electrode than to the outer Helmholtz plane.

Discreteness-of-charge effects in electrode kinetics. I. The electroreduction of tetrathionate anion in the presence of specifically adsorbed iodide anions

1982 ◽  
Vol 60 (15) ◽  
pp. 2038-2045 ◽  
Author(s):  
W. Ronald Fawcett ◽  
Kveta Markušová
Keyword(s):  
Ionic Strength ◽  
Electrode Potential ◽  
Ion Concentration ◽  
Electrode Kinetics ◽  
Charge Effect ◽  
Charge Effects ◽  
Potential Analysis ◽  
Rate Of Reaction ◽  
Kinetics Of ◽  
Outer Helmholtz Plane

The kinetics of electroreduction of tetrathionate anion have been studied at a Hg electrode in aqueous solutions of Nal + NaF and KI + KF with an ionic strength of 0.25 M. The rate of reaction was observed to decrease as the iodide ion concentration was increased, and when the cation was changed from K+ to Na+ at constant electrode potential. Analysis of the double layer effects on the basis of the Frumkin model results in an overestimation of the repulsive effect of the adsorbed iodide anions. This result is interpreted on the basis of the discreteness-of-charge effect and the possible non-coincidence of the reaction plane and outer Helmholtz plane.

Discreteness-of-charge effects in electrode kinetics. II. The electroreduction of hexamminocobalt(III) cation in the presence of specifically adsorbed nitrate anions

1983 ◽  
Vol 61 (12) ◽  
pp. 2821-2826 ◽  
Author(s):  
W. Ronald Fawcett ◽  
Kveta Markušová
Keyword(s):  
Ion Pairs ◽  
Electrode Reaction ◽  
Ion Concentration ◽  
Charge Effects ◽  
Interfacial Kinetics ◽  
Rate Of Reaction ◽  
Layer Effect ◽  
Kinetics Of ◽  
Nitrate Anions ◽  
Cation Nature

The kinetics of electroreduction of the hexamminocobalt(III) cation have been studied at a Hg electrode in aqueous solutions of NaNO3 + NaF and KNO3 + KF with an ionic strength of 0.2 M. The rate of reaction was observed to increase with increasing nitrate ion concentration but was independent of the cation nature. Analysis of the double layer effect for this system indicates that ion pairs formed between the reacting cation and anions of the base electrolyte also participate in the electrode reaction, and that attractive interactions between the reactant and adsorbed anions have a significant influence on the interfacial kinetics.

Analysis of the Electrode Kinetics of Ni(II) Reduction in Thiocyanate Media on the Dropping Mercury Electrode

2000 ◽  
Vol 65 (3) ◽  
pp. 326-342
Author(s):  
María S. Crespo-Pinilla ◽  
Fernando Mata-Pérez ◽  
Rosa M. Villamañán
Keyword(s):  
Ionic Strength ◽  
Compensation Effect ◽  
Supporting Electrolyte ◽  
Mercury Electrode ◽  
Electrode Kinetics ◽  
Surface Process ◽  
Experimental Conditions ◽  
Dropping Mercury Electrode ◽  
Kinetics Of

A study of two prewaves of the Ni(II)-SCN- system was carried out under the experimental conditions when the influence of electroreduction of SCN- is negligible. Kinetics of Ni(II) reduction in thiocyanate media on the dropping mercury electrode was studied by DC Tast Polarography (DCTP) via determination of Koutecký's parameter χ; the influence of different variables was analyzed. The study of prewaves was performed using various polarographic techniques. Values of χ depend on the SCN- concentration, pH, ionic strength (Ψ-effect) and on the nature of the supporting electrolyte. The number of electrons n, the transfer coefficient α, the stoichiometric number ν, ∆H≠, and ∆S≠ were determined (compensation effect). The first prewave has character of a reaction in the solution, the second prewave is a surface process. Main features of both mechanisms are common: catalytic nature, one-electron step discharge and the rate-determining process between species of opposite charges.

THE REACTION BETWEEN CYANATE AND HYPOCHLORITE

1956 ◽  
Vol 34 (4) ◽  
pp. 489-501 ◽  
Author(s):  
M. W. Lister
Keyword(s):  
Activation Energy ◽  
Ionic Strength ◽  
Rate Constant ◽  
Hypochlorous Acid ◽  
Effect Of Temperature ◽  
Slow Step ◽  
True Activation Energy ◽  
Rate Of Reaction ◽  
Different Temperatures ◽  
Kinetics Of

The reaction between sodium hypochlorite and potassium cyanate in the presence of sodium hydroxide has been examined. The main products are chloride, and carbonate ions and nitrogen; but, especially if much hypochlorite is present, some nitrate is formed as well. The rate of reaction is proportional to the cyanate and hypochlorite concentrations, but inversely proportional to the hydroxide concentration: the rate constant is 5.45 × 10−4 min.−1 at 65 °C, at an ionic strength of 2.2. The rate constant increases somewhat as the ionic strength rises from 1.7 to 3.5. The effect of temperature makes the apparent activation energy 25 kcal./gm-molecule. The kinetics of the reaction suggest that the slow step is really a reaction of hypochlorous acid and cyanate ions, and possible intermediate products of this reaction are suggested. Allowing for the different extent of hydrolysis of hypochlorite at different temperatures, the true activation energy is found to be 15 kcal./gm-mol., which is consistent with the observed rate of reaction.

The Effects of Adsorbed Ions on Simple Electrode Reactions. II. The Reduction Of Chromium(III) Ion in The Presence of TolueneP-Sulfonate Anions

1974 ◽  
Vol 52 (18) ◽  
pp. 3165-3169 ◽  
Author(s):  
Kamaruzzaman Alias ◽  
W. Ronald Fawcett
Keyword(s):  
Double Layer ◽  
Mercury Electrode ◽  
Diffuse Layer ◽  
Reaction Site ◽  
Electrode Reactions ◽  
Reaction Acceleration ◽  
Kinetics Of ◽  
Outer Helmholtz Plane

The kinetics of electroreduction of Cr3+ ion have been studied at a mercury electrode both in the absence and in the presence of chemisorbed toluene p-sulfonate ions. The rate of the reaction was considerably accelerated in the presence of the chemisorbed anions. Analysis of the data has shown that the reaction acceleration can be accounted for on the basis of Frumkin's theory for double layer effects suggesting that the reaction site is at the outer Helmholtz plane or close to it in the diffuse layer.

scholarly journals Acid Hydrolysis of Bis(2,2'; 6',2''–Terpyridyl) Iron(II) Complex in the Water Pools of CTAB/Hexane/Chloroform Reverse Micelles-A Kinetic Study in Confined Medium

2020 ◽  
Vol 15 (3) ◽  
pp. 853-860
Author(s):  
K. V. Nagalakshmi ◽  
P. Shyamala
Keyword(s):  
Ionic Strength ◽  
Acid Hydrolysis ◽  
Reverse Micelles ◽  
Order Rate Constant ◽  
Micellar Medium ◽  
First Order ◽  
First Order Kinetics ◽  
Rate Of Reaction ◽  
Kinetics Of ◽  
Hydrolysis Of

The kinetics of acid hydrolysis of bis(2,2';6',2''–terpyridyl) iron(II) complex has been studied in CTAB/Hexane/Chloroform reverse micelles. The reaction obeys first order kinetics with respect to each of the reactants at all values of W, {W= [H2O]/[CTAB]}. In the reverse micellar medium, the reaction is much slower compared to aqueous medium due to low micropolarity of the water pools which does not facilitate a reaction between reactants of same charge. The effect of variation of W {W=[H2O]/[CTAB]} at constant [CTAB] and variation of [CTAB] at fixed W has been studied. The second order rate constant (k2) of the reaction increases as the value of W increases up to W = 8.88 and remains constant thereafter and it is independent of concentration of [CTAB] at constant W. The variation of rate of reaction with W has been explained by considering variation of micropolarity and ionic strength of water pools of reverse micelles with W. Copyright © 2020 BCREC Group. All rights reserved 

The mean spherical approximation and medium effects in the kinetics of solution reactions involving ions

1997 ◽  
Vol 75 (11) ◽  
pp. 1649-1655 ◽  
Author(s):  
W. Ronald Fawcett ◽  
Alex C. Tikanen ◽  
Douglas J. Henderson
Keyword(s):  
Ionic Strength ◽  
Infinite Dilution ◽  
Electrolyte Concentration ◽  
Spherical Approximation ◽  
Mean Spherical Approximation ◽  
Medium Effects ◽  
Kinetics Studies ◽  
Rate Of Reaction ◽  
The Mean ◽  
Kinetics Of

The mean spherical approximation has been applied to describe medium effects in the kinetics of reactions between ions in water. When the ionic strength of the medium is altered by the addition of an inert electrolyte, the rate of reaction can be accurately predicted with the inert electrolyte concentration up to 1 M. The theoretical rate constant at the limit of infinite dilution kr0, has been estimated for five earlier kinetics studies for which data are available in the literature. Keywords: kinetic medium effects, mean spherical approximation, activity coefficients.

Study of the Cu(II) removal from aqueous solutions by adsorption on titania

2013 ◽  
Vol 12 (3) ◽  
pp. 239-247
Keyword(s):  
Heavy Metals ◽  
Ionic Strength ◽  
Toxic Metals ◽  
Low Cost ◽  
Lateral Interaction ◽  
Tio2 Surface ◽  
High Toxicity ◽  
Removal Of Heavy Metals ◽  
Solution Parameters ◽  
Kinetics Of

The removal of heavy metals from wastewaters is a matter of paramount importance due to the fact that their high toxicity causes major environmental pollution problems. One of the most efficient, applicable and low cost methods for the removal of toxic metals from aqueous solutions is that of their adsorption on an inorganic adsorbent. In order to achieve high efficiency, it is important to understand the influence of the solution parameters on the extent of the adsorption, as well as the kinetics of the adsorption. In the present work, the adsorption of Cu(II) species onto TiO2 surface was studied. It was found that the adsorption is a rapid process and it is not affected by the value of ionic strength. In addition, it was found that by increasing the pH, the adsorbed amount of Cu2+ ions and the value of the adsorption constant increase, whereas the value of the lateral interaction energy decreases.

Kinetics of hydrolysis of peroxodisulphate ions in acidic medium to peroxomonosulphuric acid

1981 ◽  
Vol 46 (5) ◽  
pp. 1229-1236 ◽  
Author(s):  
Jan Balej ◽  
Milada Thumová
Keyword(s):  
Ionic Strength ◽  
Rate Constants ◽  
Acidic Medium ◽  
Measured Data ◽  
Molar Ratios ◽  
Starting Solution ◽  
Kinetics Of Hydrolysis ◽  
Rate Of Hydrolysis ◽  
Kinetics Of ◽  
Hydrolysis Of

The rate of hydrolysis of S2O82- ions in acidic medium to peroxomonosulphuric acid was measured at 20 and 30 °C. The composition of the starting solution corresponded to the anolyte flowing out from an electrolyser for production of this acid or its ammonium salt at various degrees of conversion and starting molar ratios of sulphuric acid to ammonium sulphate. The measured data served to calculate the rate constants at both temperatures on the basis of the earlier proposed mechanism of the hydrolysis, and their dependence on the ionic strength was studied.

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