Kinetics and mechanism of the redox reaction of orange II with thiosulphate ion in aqueous acid

The kinetics of the redox reaction of orange II (OR-) with thiosulphate ion has been studied spectrophotometrically at constant ionic strength, I = 0.50 mol dm-3 (NaCl), [H+] = 5.0 X 10-2 mol dm-3 (HCl) and T = 26 ± 1°C. The redox reaction displayed a stoichiometry of 1:4 and rate equation for the reaction is-d[OR-]/dt = (a + b[H+])[OR-][S2O32-]The rate of the reaction increases with increase in acid concentration and in the ionic strength of reaction medium. The reaction shows a first order dependence on [oxidant] and [reductant]. Added cations and anions inhibited the rate of the reaction. Michaelis – Menten’s plot of 1/k1 versus 1/ S2O32- and spectrophotometric test suggest absence of an intermediate in the rate determining step. Free radical test did not yield gel formation. Based on the results obtained, this reaction is probably operating through the outersphere mechanism

Preliminary Study on the Kinetics and Mechanism of the Oxidation of Naphthol Green B by Dichromate Ion in Aqueous Hydrochloric Acid Medium

- The kinetics of the oxidation of naphthol green B (NGB3-) by Cr2O7 2- has been studied in aqueous hydrochloric acid medium at an ionic strength, I = 0.50 mol dm-3 (NaCl), H+ =1.0 10-4 mol dm-3 (HCl) and T = 25 1C. The redox reaction displayed a stoichiometry of 1:1 and obeys the rate law: -dNGB3-/dt = k2NGB3-]Cr2O7 2- . The second order rate constant increases with increase in acid concentration and in the ionic strength of reaction medium. The rates of reaction displayed a positive salt effect. Addition of acrylonitrile to a partially reacted mixture in the presence of excess methanol did not lead to gel formation. Added cations and anions inhibited the naphthol green B - Cr2O7 2- reaction. Results of the Michaelis – Menten plot gave no evidence of intermediate complex formation during the course of the reaction. Based on the results obtained, the reaction is believed to proceed through the outersphere mechanistic pathway

Kinetics and Mechanism of the Oxidation of Orange II by Chlorate Ion in Aqueous Hydrochloric Acid

Communication in Physical Sciences 2020, 5(2):165-170 Authors: B. Myek, S. O. Idris, A. D. Onu and M. K. Yakubu Received 05 March 2020/Accepted 03 May 2020 The kinetics of the oxidation of orange II (OR-) by ClO3-was studied in aqueous hydrochloric acid where the ionic strength and other parameters of the reaction mixture was, I = 0.50 mol dm-3 (NaCl), [H+] = 5.0 10-2 mol dm-3 (HCl) and T = 21 +/_ 1o C. The redox reaction displayed a stoichiometry of 1:2 and obeys the rate law given as,−????[????????−]/???????? = ????[????][????????][???????????? ]. The observed second order rate constant was found to increases with increase in hydrogen ion concentration. The rates of reaction displayed a zero salt effect and was inhibited by some added cations and anions. From the Michaelis-Menton Buck plot, there was no evidence for the formation of intermediate during the course of the reaction. Based on the results obtained, the outersphere mechanism was proposed for the reaction.&nbsp

Synthesis of an azo dye and its cobalt complex derived from 3-aminophenol

Communication in Physical Sciences 2020, 6(1): 722-725 Gideon Wyasu*,  B. Myek and Sunday Solomon Received 19 May 2020/Accepted 20 September 2020 An azo dye derived from 3-aminophenol and its cobalt complex have been synthesized and characterized using Fourier transformed and ultraviolet visible spectrophotometer. The ligand (dye) exhibited an absorption maximum at 470 nm but the absorbance maxima for the synthesized Schiff base complex deviated from 470 to 473 nm which indicated the existent of interaction between the cobalt and the ligand to form metal-dye complex. Moreover, the infrared absorbance band for -N=N- stretching vibration at 1513.3 cm-1 for azo dye nut in the complex the frequency shifted to 1457.4 cm-1. The calculated percentage yield of the azo dye was found to be 84% while that of its cobalt complex was 59%

KINETICS OF THE OXIDATION OF ORANGE II BY NITRITE ION IN AQUEOUS ACIDIC MEDIUM

The kinetics of the electron transfer reaction between Orange II(here and thereafter referred to as OII-) and nitrite ion in aqueous acidic solution has been studied spectrophotometrically (λ = 484 nm) at T = 27 ± 1oCin the acid range 1.0 × 10-2 ≤ [H+] ≤ 10.0 × 10-2 mol dm-3, ionic strength 0.1 ≤ [I] ≤ 0.7 mol dm-3 (NaCl). The reaction shows a first order dependence on [oxidant] and [reductant].The rate of the reaction increases with increase in [H+]. Plot of k2versus [H+] was linear with an intercept. The overall reaction conforms to the rate law: -d[OII-]/dt = (a + b[H+])[OII-][NO2-] The stoichiometry of the reaction is 1:2 (OII- : NO2-). Added cations and anions speed up the rate of the reaction. The results of spectroscopic investigation indicate that no intermediate complex is probably formedin the course of this reaction. The reaction is believed to proceed via the outersphere mechanistic pathway.&nbsp

Synthesis and Characterization of Metal Complex of an Azo Dye Based on Acid Orange 7

Authors: B. Myek, M. L. Batari, J. O. Orijajogun and M. A. Aboki Received 20 May 2020/Accepted 29 June 2020 Azo dye which serve as a ligand was prepared by diazotization of primary aromatic amine to form the diazonium salt. The relatively unstable diazonium salt thus formed was reacted with a coupling component. Complex of this ligand has been synthesized and characterized by IR spectroscopy and UV- Visible absorption spectroscopy. The absorption maximum of the ligand was at 483.50nm. Upon binding with the Fe(II) the band shifted to 479.50nm,  indicates an interaction of the Fe(II)  with the ligand. The ligand synthesized is soluble in water as well as its metal complex. The colour of the ligand is orange while that of the complex is brown. The prepared complex is stable at room temperature