Temperature-dependence of electrochemical kinetic parameters: Electrode reaction of the Zn(Hg)/Zn(II) system

1982 ◽  
Vol 47 (5) ◽  
pp. 1433-1443 ◽  
Author(s):  
S. Kang ◽  
K. Matsuda ◽  
R. Tamamushi
Keyword(s):  
Aqueous Solutions ◽  
Temperature Dependence ◽  
Kinetic Parameters ◽  
Rate Constant ◽  
Activation Parameters ◽  
Electrode Reaction ◽  
Thermodynamic Quantities ◽  
Empirical Correlations ◽  
Square Wave ◽  
Different Temperatures

The electrochemical kinetic parameters of the D.M.E./Zn(II) electrode reaction in aqueous solutions containing perchlorate, nitrate, chloride and bromide ions were measured at different temperatures (5-50 °C) by the modified square-wave polarographic technique. The Arrhenius activation parameters and thermodynamic quantities of the electrode reaction were determined from the temperature dependence of the rate constant and conditional potential, respectively. Empirical correlations were observed between some pairs of kinetic and thermodynamic quantities.

scholarly journals Mechanistic aspects of oxidation on L-tyrosine by diperiodatocuprate(III) complex in alkali media: a kinetic model

2009 ◽  
Vol 7 (4) ◽  
pp. 929-937 ◽  
Author(s):  
Nagaraj Shetti ◽  
Rajesh Hegde ◽  
Sharanappa. Nandibewoor
Keyword(s):  
Alkaline Medium ◽  
Activation Parameters ◽  
Spectral Studies ◽  
Slow Step ◽  
Isokinetic Temperature ◽  
Thermodynamic Quantities ◽  
Radical Intermediate ◽  
Different Temperatures ◽  
Reactive Oxidant ◽  
Reaction Constants

AbstractOxidation of an amino acid, L-tyrosine (L-Tyr) by diperiodatocuprate(III) (DPC) in alkaline medium at a constant ionic strength of 0.1 mol dm−3 was studied spectrophotometrically at different temperatures (288.1–313.1 K). The reaction between DPC and L-Tyr in alkaline medium exhibits 1:4 stoichiometry (L-Tyr:DPC). Intervention of free radicals was observed in the reaction. Based on the observed orders and experimental evidence, a mechanism involving monoperiodatocuprate(III) (MPC) as the reactive oxidant species has been proposed. A suitable mechanism is proposed through the formation of a complex and free radical intermediate. The products were identified by spot test and characterized by spectral studies. The reaction constants involved in the different steps of the mechanism were calculated. The activation parameters with respect to slow step of the mechanism were computed and are discussed. The thermodynamic quantities were determined for different equilibrium steps. Isokinetic temperature was also calculated and found to be 252.3 K.

Polarographic and Cyclic Voltammetric Behaviour of Some Azo Compounds Derived from Sulfonamide in DMF-Aqueous Solutions

1992 ◽  
Vol 57 (2) ◽  
pp. 268-275 ◽  
Author(s):  
El-Sayed M. Mabrouk ◽  
Hamada M. Killa ◽  
Abdel Fattah A. Abdel Fattah ◽  
Shalaby A. Yasen
Keyword(s):  
Reaction Mechanism ◽  
Aqueous Solutions ◽  
Kinetic Parameters ◽  
Alkaline Solution ◽  
Electrode Reaction ◽  
Azo Compounds ◽  
Cyclic Voltammetric ◽  
Ph Range

The polarographic and cyclic voltammetric behaviour of (2-hydroxyphenylazo)-4-benzenesulfonamide and some of its derivatives have been studied in Britton-Robinson buffer series containing 30 vol.% of DMF. Over the entire pH range (2-12), the reduction pathway occurs through an irreversible 4-electron step corresponding to the reduction of N=N center to the amine stage. The voltammograms recorded in acidic and alkaline solution at different scan rates exhibit one or two cathodic peaks depending on the substituent and the pH of the medium. The electrode reaction mechanism was suggested, also the kinetic parameters were calculated.

scholarly journals Theory of reverse scan square-wave voltammetry influenced by the kinetics of reactant adsorption

2010 ◽  
Vol 8 (3) ◽  
pp. 513-518 ◽  
Author(s):  
Milivoj Lovrić ◽  
Šebojka Komorsky-Lovrić
Keyword(s):  
Rate Constant ◽  
Square Wave Voltammetry ◽  
Electrode Reaction ◽  
Peak Current ◽  
Kinetics Of Adsorption ◽  
Square Wave ◽  
Wave Voltammetry ◽  
Reverse Scan ◽  
The Relationship ◽  
Kinetics Of

AbstractA model of electrode reaction complicated by slow adsorption of the reactant is developed for square-wave voltammetry with inverse scan direction. The relationship between the dimensionless net peak current and the logarithm of dimensionless rate constant of adsorption is a curve with a minimum and a maximum. For this reason the ratio of real net peak current and the square-root of frequency is a non-linear function of the logarithm of frequency and exhibits either a maximum or a minimum. The frequency of extreme serves for the estimation of the rate constant: log(k ads /D 1/2 ) = log(k*ads )crit + 0.5 log f crit , where (k*ads )crit is a critical dimensionless rate constant of adsorption. Square-wave voltammetry is sensitive to the kinetics of adsorption if k ads 2 cm s−1

scholarly journals Catalytic influence of 16- s -16 gemini surfactants on the rate constant of histidine and ninhydrin

2020 ◽  
Vol 7 (2) ◽  
pp. 191648 ◽  
Author(s):  
Dileep Kumar ◽  
Malik Abdul Rub
Keyword(s):  
Critical Micelle Concentration ◽  
Rate Constant ◽  
Gemini Surfactants ◽  
Conductivity Measurement ◽  
Activation Parameters ◽  
Resultant Data ◽  
Different Temperatures ◽  
Eyring Equation ◽  
Constant Characteristics ◽  
Systematic Explanation

The present paper reports the catalytic influence of 16- s -16 (spacer ( s ) = 4, 5, 6) gemini surfactants on the rate constant of histidine and ninhydrin at 343 K and pH 5.0 using the spectrophotometric technique. The effect of varying amounts of geminis was made on the rate constant of histidine and ninhydrin keeping other constituents constant. Characteristics of the rate constant ( k ψ ) versus [gemini] depict the effect of surfactants on the rate constant. A systematic explanation about the effect of surfactants is revealed and discussed in the text. The influence of different parameters that includes [reactants], temperature and pH has also been performed on the study. In order to determine the critical micelle concentration (cmc) of pure surfactants and their solution mixtures, conductivity measurement was employed. By using the Eyring equation, activation parameters at different temperatures have been obtained. The resultant data of k ψ versus [gemini] plot were rationalized with the pseudo-phase model of micelles.

scholarly journals Kinetics of gibbsite leaching in sodium hydroxide aqueous solution

2002 ◽  
Vol 56 (9) ◽  
pp. 381-385
Author(s):  
Ljubica Pavlovic ◽  
Zagorka Acimovic-Pavlovic ◽  
Ljubisa Andric ◽  
Aurel Prstic
Keyword(s):  
Activation Energy ◽  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Sodium Hydroxide ◽  
Kinetic Parameters ◽  
Rate Constant ◽  
Reaction Rate ◽  
Reaction Rate Constant ◽  
Kinetics Of ◽  
Mechanism Of The Reaction

In order to study the kinetics and mechanism of the reaction, laboratory leaching was carried out with industrially produced gibbsite ?-Al(OH)3 in aqueous solutions containing an excess of sodium hydroxide. The results obtained reaction temperature, duration and base concentration varied. The basic kinetic parameters were determined from: the reaction rate constant k=8.72?107 exp (-74990/RT) and the process activation energy in the range Ea=72.5-96.81 kJ/mol.

Thermodynamic Investigations of Thin Liquid Layers Between Solid Surfaces II. Water Between Entirely Hydroxylated Fused Silica Surfaces

1971 ◽  
Vol 26 (4) ◽  
pp. 707-715 ◽  
Author(s):  
G. Peschel ◽  
K. H. Adlfinger
Keyword(s):  
Physical Properties ◽  
Temperature Dependence ◽  
Fused Silica ◽  
Solid Surfaces ◽  
Special Method ◽  
Surface Zone ◽  
Thermodynamic Quantities ◽  
Silica Surfaces ◽  
Different Temperatures ◽  
Aqueous Surface

Abstract By a special method the disjoining pressure of water caused by a molecular long range orienta­tion between fully hydroxylated and highly polished fused silica surfaces at different temperatures (0-74 °C) and plate distances ≦ 1000 Å was determined. Four marked maxima were found at about 15°, 32°, 45°, and 61 °C for not too small plate distances. At these temperatures many authors have detected anomalies in the temperature dependence of some physical properties of water. This evidence is discussed in regard to our results which particularly imply thermodynamic quantities derived from the aqueous surface zone.

Kinetic and Mechanistic Aspects of Osmium(VIII) Catalyzed Oxidation of DL-ornithine by Copper(III) Periodate Complex in Aqueous Alkaline Medium

2010 ◽  
Vol 224 (06) ◽  
pp. 865-882 ◽  
Author(s):  
Jyothi C. Abbar ◽  
Shweta J. Malode ◽  
Sharanappa T. Nandibewoor
Keyword(s):  
Alkaline Medium ◽  
Activation Parameters ◽  
Reaction Rates ◽  
Oxidation Products ◽  
Slow Step ◽  
Thermodynamic Quantities ◽  
Aqueous Alkaline Medium ◽  
Uncatalyzed Reaction ◽  
Different Temperatures ◽  
Reaction Constants

AbstractThe oxidation of DL-ornithine monohydrochloride (OMH) by diperiodatocuprate(III) (DPC) has been investigated in the presence of osmium(VIII) catalyst in aqueous alkaline medium at a constant ionic strength of 0.20 mol dm−3 spectrophotometrically. The reaction exhibits 1:4 stoichiometry i.e., [OMH]: [DPC]. The order of the reaction with respect to [DPC] was unity while the order with respect to [OMH] was less than unity over the concentration range studied. The rate increased with an increase in [OH –] and decreased with an increase in [IO4−]. The order with respect to [Os(VIII)] was unity. The reaction rates revealed that Os(VIII) catalyzed reaction was about nine-fold faster than the uncatalyzed reaction. The oxidation products were identified by spectral analysis. Suitable mechanism has been proposed. The reaction constants involved in the different steps of the reaction mechanism were calculated. The catalytic constant (KC) was also calculated at different temperatures. The activation parameters with respect to slow step of the mechanism and also the thermodynamic quantities were determined. Kinetic experiments suggest that [OsO4(OH)2]2− is the reactive Os(VIII) species and [Cu(H2IO6)(H2O)2] is the reactive copper(III) species.

Thermodynamical detection of hydrophobic hydration of tris(2,4-pentanedionato)-cobalt(III) and tris(3,5-heptanedionato)cobalt(III) in water

1991 ◽  
Vol 69 (9) ◽  
pp. 1388-1393 ◽  
Author(s):  
Yasuki Yoshimura
Keyword(s):  
Free Energy ◽  
Aqueous Solutions ◽  
Temperature Dependence ◽  
Key Words ◽  
Thermodynamic Parameters ◽  
Hydrophobic Hydration ◽  
Thermodynamic Quantities ◽  
Temperature Range ◽  
Entropy Formula ◽  
Energy Formula

The solubilities of tris(2,4-pentanedionato)cobalt(III) and tris(3,5-heptanedionato)cobalt(III) in water, heptane, and 1,2-ethanediol were determined over the temperature range 5–50 °C and from these data the thermodynamic quantities of solution at 25 °C were estimated. The free energy [Formula: see text], enthalpy [Formula: see text], and entropy [Formula: see text] of transfer of these chelates from heptane to some solvents were calculated from the corresponding thermodynamic quantities of solution. When [Formula: see text] and [Formula: see text] were separately plotted against [Formula: see text], the data of transfer from heptane to water deviated markedly from a correlation obtained for the data of transfer to the solvents other than water. This finding indicates that these chelates are subject to hydrophobic hydration in their aqueous solutions. The solubility of tris(glycinato)cobalt(III) in water was also determined over the temperature range 5–60 °C and its temperature dependence of the solubility is compared with that for the cobalt(III) chelates of the β-diketones. Key words: tris cobalt(III) chelates of β-diketones and glycine, temperature dependence of solubility, thermodynamic parameters of solution, thermodynamic parameters of transfer, hydrophobic hydration.

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