scholarly journals Kinetics and Mechanism of Redox Reaction of Neutral Red with Nitrite Ion in Aqueous Acidic Medium

2016 ◽  
Vol 67 ◽  
pp. 50-57
Author(s):  
Ismaila Ibrahim ◽  
Sulaiman Ola Idris ◽  
Ameh David Onu
Keyword(s):  
Redox Reaction ◽  
Outer Sphere ◽  
Neutral Red ◽  
Nitrite Ion ◽  
First Order ◽  
Hydrochloric Acid Medium ◽  
Plausible Mechanism ◽  
Kinetics Of ◽  
Sphere Mechanism ◽  
Aqueous Acidic Medium

The kinetics of redox reaction of neutral red, NR+, with nitrite ion, NO2-, was studied in aqueous hydrochloric acid medium under pseudo-first order conditions at 25 ± 1°C, [H+] = 2.0 × 10-3mol dm-3, I = 0.1 mol dm-3(NaCl) and λmax= 525 nm. The reaction was first order with respect to [NR+], [NO2-] and [H+]. The reaction displayed a negative Bronsted-Debye salt effect. There was no evidence of the formation of an intermediate complex of significant stability and free radicals are probably not present in the reaction. The observations above, coupled with the result of Michaelis-Menten plot suggests an outer sphere mechanism for the reaction. The reaction obeys the rate law: -d [NR+]/dt = (a + b [H+])[NR+][NO2-]. A plausible mechanism has been proposed for the reaction.

scholarly journals Reduction of tris(2,2’-bipyridine)cobalt(III) complex by thiosulphate ion in an aqueous acidic medium

2021 ◽  
Author(s):  
C.R. Osunkwo ◽  
I.U. Nkole
Keyword(s):  
Acidic Medium ◽  
Outer Sphere ◽  
Reaction Rates ◽  
Ion Concentration ◽  
Third Order ◽  
Hydrogen Ion Concentration ◽  
First Order ◽  
First Order Method ◽  
Sphere Mechanism ◽  
Aqueous Acidic Medium

Abstract The reduction of tris(2,2-bipyridine)cobalt(III) complex by thiosulphate ion in an aqueous acidic medium gave a notable outcome. The stoichiometric evaluation indicates that one mole of the reducing agent has been consumed by one mole of the oxidant, and the reaction complies with an overall equation: 2[Co(bpy)3]3+ + 2S2O32− 2[Co(bpy)3]2+ + S4O62− The kinetics study conducted under a pseudo-first-order method shows that the rate of the reaction was acid-reliant and third-order overall; zero-order in the [oxidant], second-order in the [reductant], and first-order in the hydrogen ion concentration. The empirical rate expression complies with the equation:− [Co(bpy)33+] = a [H+][S2O32−]2‘a’ = 77.82 dm6 mol−2 s−1; at [H+] = 2.0 × 10−2 mol dm−3, µ = 0.4 mol dm−3 (NaCl), T = 28 ± 1˚C and λmax = 560 nm.With increased ionic strength and decreased medium dielectric constant, the reaction rate increased. The inclusion of cations and anions accelerate and constricted the reaction rates respectively. Spectroscopic examination and kinetic evidence indicate an outer sphere mechanism, and the mechanism was therefore proposed via an outer-sphere route.

scholarly journals The Kinetics of the Oxidation of Lysine by μ-Peroxo-Bridged Binuclear Cobalt (III) Complex of Succinimide in Aqueous Hydrochloric Acid Medium

2017 ◽  
Vol 2 (1) ◽  
pp. 37-43
Author(s):  
Ahmed Adetoro ◽  
Suleiman O. Idris ◽  
Ameh D. Onu ◽  
Friday G. Okibe
Keyword(s):  
Ionic Strength ◽  
Outer Sphere ◽  
Hydrogen Ions ◽  
First Order ◽  
Hydrochloric Acid Medium ◽  
State Approximation ◽  
Steady State Approximation ◽  
Probable Reaction ◽  
Electron Transfer Processes ◽  
Kinetics Of

AbstractKinetics of oxidation of Lysine (Lys) and mechanisms by μ-peroxo bis[bis(ethylenediamine)succinimidato-dicobalt(III)]dinitratedihydrate; [LCo(μ-O2)CoL](NO3)2.2H2O (L = suc(en)2), hereafter the complex, was investigated at 420 nm wavelength of maximum absorption of the complex under the conditions hydrogen ions concentration = 1.8 × 10−2 mol dm−3, temperature = 24 ± 1 °C, [LCo(μ-O2)CoL2+] = 1.4 × 10−4 mol dm−3 and ionic strength = 0.5 mol dm−3. First order in [LCo(μ-O2)CoL2+] and [Lys] were obtained but inverse first order in [H+]. The proposed overall rate equation is as shown:$$Rate = ({{k_1 } \over {k_2 }} + {{K_1 k_3 } \over {k_4 }}{1 \over {[H^ + ]}})[LCo(\mu O_2 )CoL^{2 + } ][Lys]$$Rate of the reaction decreases when hydrogen ions concentration increase and exhibited converse effect with increase in concentration of ionic strength from 0.1 – 1.3 mol dm−3. Added cations and anions affected the reaction rate and the Michaelis-Menten plot passed through the origin indicating no absence of intermediate complex in the electron transfer processes. Putting all the results obtained together, the most probable reaction mechanism is in favour of outer-sphere and an appropriate rate law is established using steady state approximation.

scholarly journals The Kinetics of the Oxidation of Lysine by μ-Peroxo-Bridged Binuclear Cobalt (III) Complex of Succinimide in Aqueous Hydrochloric Acid Medium

2017 ◽  
Vol 0 (0) ◽  
Author(s):  
A Adetoro ◽  
S.O. Idris ◽  
A.D. Onu ◽  
F.G Okibe
Keyword(s):  
Ionic Strength ◽  
Outer Sphere ◽  
Hydrogen Ions ◽  
First Order ◽  
Hydrochloric Acid Medium ◽  
State Approximation ◽  
Steady State Approximation ◽  
Probable Reaction ◽  
Electron Transfer Processes ◽  
Kinetics Of

Abstract Kinetics of oxidation of Lysine (Lys) and mechanisms by μ-peroxo bis[bis(ethylenediamine)succinimidato-dicobalt(III)]dinitratedihydrate; [LCo(μ-O2)CoL](NO3)2.2H2O (L = suc(en)2), hereafter the complex, was investigated at 420 nm wavelength of maximum absorption of the complex under the conditions hydrogen ions concentration = 1.8 × 10-2 mol dm-3, temperature = 24 ± 1 °C, [LCo(μ-O2)CoL2+] = 1.4 × 10-4 mol dm-3 and ionic strength = 0.5 mol dm-3. First order in [LCo(μ- O2)CoL2+] and [Lys] were obtained but inverse first order in [H+]. The proposed overall rate equation is as shown: Rate of the reaction decreases when hydrogen ions concentration increase and exhibited converse effect with increase in concentration of ionic strength from 0.1 - 1.3 mol dm-3. Added cations and anions affected the reaction rate and the Michaelis-Menten plot passed through the origin indicating no absence of intermediate complex in the electron transfer processes. Putting all the results obtained together, the most probable reaction mechanism is in favour of outer-sphere and an appropriate rate law is established using steady state approximation.

scholarly journals Kinetics of the Oxidation of Bromopyrogallol Red by Nitrite Ion in Aqueous Acidic Medium

2015 ◽  
Vol 3 ◽  
pp. 32-38 ◽  
Author(s):  
Sulaiman Ola Idris ◽  
V.O. Samson ◽  
B. Myek
Keyword(s):  
Transfer Reaction ◽  
Acidic Solution ◽  
Electron Transfer Reaction ◽  
Nitrite Ion ◽  
First Order ◽  
Bromopyrogallol Red ◽  
Mechanistic Pathway ◽  
Kinetics Of ◽  
Acid Range ◽  
Aqueous Acidic Medium

The kinetics of the electron transfer reaction between Bromopyrogallol (BPR2-) and nitrite ion in aqueous acidic solution has been studied in the acid range 0.1 × 10-4 ≤ [H+] ≤ 2 × 10-4 mol dm-3, ionic strength 0.01 ≤ ≤ 0.18 mol dm-3 (NaCl) and T = 29 ± 1.°C. The reaction shows a first order dependence on oxidant and reductant concentration respectively. The rate of the reaction increases with increase in [H+]. Plot of k2 versus [H+] was linear with a positive intercept. The overall reaction conforms to the rate law: -d[BPR2-]/dt = (a + b[H+])[BPR2][NO2-]. The stoichiometry of the reaction is 1:1 (BPR2- : NO2-). Added anions had no effect on the rate of the reaction. The results of spectroscopic investigation indicate that no intermediate complex is probably formed in the course of this reaction. The reaction is believed to proceed via the outersphere mechanistic pathway.

scholarly journals Synthesis and Oxidation ofCobalt(II) Pheophytin-α Complex

2011 ◽  
Vol 8 (s1) ◽  
pp. S297-S303 ◽  
Author(s):  
Ezekiel D. Dikio ◽  
David A. Isabirye
Keyword(s):  
Metal Ion ◽  
Oxidation Reaction ◽  
Dilute Hydrochloric Acid ◽  
Outer Sphere ◽  
Central Metal ◽  
First Order ◽  
First Order Kinetics ◽  
Mechanism Of Oxidation ◽  
Absorption Transitions ◽  
Sphere Mechanism

The mechanism of oxidation of natural pheophytin-aincorporated with cobalt as the central metal ion has been investigated. Natural pheophytin-aextracted from spinach was metallated with cobalt(II) to form the complex, cobalt(II) pheophytin-α[Cophe]. The complex was characterized by Ultraviolet and Visible, Fourier Transform Infrared and Electrospray ion Mass Spectroscopy. The synthesis of cobalt(II) pheophytin-awas carried out and the effect of the substitution on the chlorophyll macrocycle was studied by the reaction of hexaaquachromium(III) cation. The presence of cobalt as the central metal ion increases the energies of the chlorophyll main absorption transitions. The oxidation of the cobalt(II) pheophytin-α, [Cophe] by hexaaquachromium(III) cation in dilute hydrochloric acid has been studied and found to follow first-order kinetics. Rate constants for the oxidation reaction at 313, 322.8 and 332.9 K were found to be 5.4×10-5, 1.8×10-4and 5.9×10-4/s respectively. An outer-sphere mechanism has been proposed for the oxidation of cobalt(II) pheophytin-α.

scholarly journals Kinetics and Mechanism of Oxidation of Diethanolamine and Triethanolamine by Potassium Ferrate

2011 ◽  
Vol 8 (2) ◽  
pp. 903-909 ◽  
Author(s):  
Shan Jinhuan ◽  
Zhang Jiying
Keyword(s):  
Activation Parameters ◽  
Rate Equations ◽  
Potassium Ferrate ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Order Dependence ◽  
Rate Determining Step ◽  
Thermodynamic Activation Parameters ◽  
Plausible Mechanism ◽  
Kinetics Of

The kinetics of oxidation of diethanolamine and triethanolamine by potassium ferrate(VI)in alkaline liquids at a constant ionic strength has been studied spectrophotometrically in the temperature range of 278.2K-293.2K. The reaction shows first order dependence on potassium ferrate(VI), first order dependence on each reductant, The observed rate constant (kobs) decreases with the increase in [OH-], the reaction is negative fraction order with respect to [OH-]. A plausible mechanism is proposed and the rate equations derived from the mechanism can explain all the experimental results. The rate constants of the rate-determining step and the thermodynamic activation parameters are calculated.

scholarly journals KINETICS OF REACTION BETWEEN MALACHITE GREEN AND HYDROXYL ION IN THE PRESENCE OF REDUCING SUGARS

2015 ◽  
Vol 23 (23) ◽  
pp. 61-72
Author(s):  
Dayo Felix Latona ◽  
Adewumi Oluwasogo Dada
Keyword(s):  
Malachite Green ◽  
Activation Parameters ◽  
Cell Compartment ◽  
First Order ◽  
Rate Determining Step ◽  
First Order Kinetics ◽  
Hydroxyl Ion ◽  
Kinetics Of Reaction ◽  
Kinetics Of ◽  
Sphere Mechanism

The reaction was studied via pseudo-first-order kinetics using a UV-1800 Shimadzu spectrophotometer with a thermostated cell compartment and interfaced with a computer. The reaction showed first order with respect to malachite green and sugar and hydroxyl ion concentrations. However, the reaction was independent of ionic strength and showed no dependence on the salt effect, indicating an inner sphere mechanism for the reaction. There was no polymerization of the reaction mixture with acrylonitrile, indicating the absence of radicals in the course of the reaction. Michaelis-Menten plot indicated the presence of a reaction intermediate in the rate-determining step. The activation parameters of the reaction have been calculated and products were elucidated by FTIR spectroscopy. The stoichiometry of the reaction is 1:1. A mechanism consistent with the above facts has been suggested.

scholarly journals Kinetic Approach to the Reduction of Ethylenediaminetetraacetatoferrate(III) Complex by Iodide Ion in Aqueous Acidic Medium

2019 ◽  
pp. 1-8
Author(s):  
I. U. Nkole ◽  
C. R. Osunkwo
Keyword(s):  
Acidic Medium ◽  
Salt Effect ◽  
Outer Sphere ◽  
Ion Concentration ◽  
Kinetic Approach ◽  
Edta Complex ◽  
Electron Transfer Mechanism ◽  
First Order ◽  
Iodide Ion ◽  
Aqueous Acidic Medium

The kinetic approach to the reduction of ethylenediaminetetraacetatoferrate(III) complex (hereafter [Fe(III)EDTA]-) by iodide ion has been studied spectrophotometrically in an aqueous acidic medium. The study was carried out under pseudo-first order conditions of an excess of iodide ion concentration at 28 ± 1, ionic strength (I) = 0.43 coulomb2 mol dm-3 (KNO3) and [H+] = 5.0  10-2 mol dm-3. The [Fe(III)EDTA]- complex was reduced according to the reaction; 2[Fe(III)EDTA]- + 2I-  → 2[Fe(II)EDTA]2- + I2 The rate law is - d[Fe(III)EDTA-]/dt = (a + b[H+])[Fe(III)EDTA-][I-] The rate of the reaction is first order in oxidant and reductant concentrations, and displayed positive Brønsted-Debye salt effect. On the basis of catalysis by added cation, Michaelis-Menten plots and the absence of intermediates, the outer-sphere electron transfer mechanism is proposed for the reaction.

Kinetics of oxidation of α-ketoglutaric acid with Ce(IV) ions in relation to Belousov-Zhabotinskii reaction

1982 ◽  
Vol 47 (11) ◽  
pp. 2831-2837 ◽  
Author(s):  
Ľudovít Treindl ◽  
Vasil Dorovský
Keyword(s):  
Redox Reaction ◽  
Platinum Electrode ◽  
Activation Parameters ◽  
Enol Form ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Redox Catalyst ◽  
Oscillation Reaction ◽  
Belousov Zhabotinskii Reaction ◽  
Kinetics Of

Oxidation of α-ketoglutaric acid with Ce(IV) ions in a solution of sulphuric acid is a reaction of the first order with respect to both Ce(IV) ions and substrate, is acid catalysed, and its rate is proportional to the reciprocal square of the equilibrium HSO4- concentration. From the temperature dependence of the rate constant in 1.5M-H2SO4, the activation parameters were determined as ΔH##f = 57 kJ/mol and ΔS##f = -45 J mol-1 K-1. The redox reaction proper consists apparently of two steps: in the first one, the enol form of α-ketoglutaric acid reacts with Ce(IV) ions with the formation of the corresponding radical; in the second one, the latter is oxidized further with Ce(IV) to give malonic and succinic acids. Conditions are indicated under which α-ketoglutaric acid serves as substrate for the Belousov-Zhabotinskii oscillation reaction in the presence of Ce(IV)-Ce(III) redox catalyst. Oscillations of Ce(IV) and Br2 concentrations, shifted in phase, can be recorded polarographically with a rotating platinum electrode.

scholarly journals Kinetics and Mechanism of the Oxidation of Naphthol Green B by Peroxydisulphate Ion in Aqueous Acidic Medium

2014 ◽  
Vol 2014 ◽  
pp. 1-4
Author(s):  
B. Myek ◽  
S. O. Idris ◽  
J. F. Iyun
Keyword(s):  
Acidic Medium ◽  
Reaction Medium ◽  
Intermediate Complex ◽  
Kinetic Investigation ◽  
Hydrogen Ions ◽  
First Order ◽  
Order Dependence ◽  
Naphthol Green B ◽  
Kinetics Of ◽  
Aqueous Acidic Medium

The kinetics of the oxidation of naphthol green B (NGB3−) by peroxydisulphate ion has been carried out in aqueous acidic medium at λmax of 700 nm, T=23±1°C, and I=0.50 mol dm−3 (NaCl). The reaction shows a first-order dependence on oxidant and reductant concentration, respectively. The stoichiometry of the NGB—S2O82- reaction is 1 : 2. Change in hydrogen ions concentration of the reaction medium has no effect on the rate of the reaction. Added cations and anions decreased the rate of the reaction. The results of spectroscopic and kinetic investigation indicate that no intermediate complex is probably formed in the course of this reaction.

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