Kinetics and mechanism of oxidation of arsenic(III) by quinolinium dichromate(QDC) in aqueous perchloric acid

388-393The kinetics of oxidation of arsenic(III) by quinolinium dichromate(QDC) has been investigated spectrophotometrically over a wide range of arsenic(III) concentrations in aqueous perchloric acid medium and at a constant ionic strength. As the arsenic(III) concentration varies, from lower concentration region to higher one, the order with respect to [arsenic(III)] changes from first to zero order. In all the regions of the [arsenic(III)], the reaction is first order in [oxidant] and less than unit order in [acid] . Increase in [perchloric acid] accelerates the reaction rate. The added products, chromium(III) and arsenic(V) do not significantly affect the reaction rate. A suitable mechanism is proposed and the involved reaction constants have been evaluated. Activation parameters have also been calculated

Mechanism of oxidation of hexamine by quinoliniumdichromate (QDC) in aqueous perchloric acid

459-465The kinetics of oxidation of hexamine by quinoliniumdichromate (QDC) has been investigated spectrophotometrically in aqueous perchloric acid medium at constant ionic strength. The reaction is first order with respect to oxidant and reductant. Increase in perchloric acid concentration increases the reaction rate and order with respect to acid concentration is nearly two. The added products chromium(III), formaldehyde and oxime do not have any significant effect on the rate of reaction. Increase in ionic strength and decrease in dielectric constant of the reaction medium increases the rate of reaction. A suitable mechanism is proposed and the constants involved have been obtained. The activation parameters were evaluated with respect to slow step of the mechanism and discussed

Kinetics of palladium(II) catalysed oxidation of mercury(I) by iron(III)-2,2'-bipyridyl complex

316-320Kinetics of oxidation of mercury(I) by iron(III)-2,2'-bipyridyl in the presence of microamounts of palladium(II) has been studied spectrophotometrically in aqueous nitric acid and methanol media. The reaction exhibits first order each in [iron(III)-2,2ʹ-bipyridyl ] and [palladium(II)] and zero order in [mercury(I). Increase in [HNO3] decreases the reaction rate. Added products do not have any significant effect on the reaction rate. A suitable reaction mechanism is proposed and the reaction constants of the different steps involved have been evaluated

A study of the ruthenium(III) catalysed oxidation of L-phenylalanine by heptavalent manganese-A kinetic and mechanistic approach

1850-1855The kinetics of the ruthenium(III) catalysed oxidation of L-phenylalanine by alkaline permanganate has been studied spectrophotometrically using a rapid kinetic accessory. The reaction is first order each in [oxidant] and [catalyst] with an apparent less than unit order each in [substrate] and [alkali] respectively. The results suggest the formation of a complex between the phenylalanine and the hydroxylated species of ruthenium(III). The complex reacts further with the alkaline permanganate species in a rate-determining step, resulting in the formation of a free radical, which again reacts with the alkaline permanganate species in a subsequent fast step to yield the products. The reaction constants involved in the mechanism and the activation parameters have been calculated. There is a good agreement between observed and calculated rate constants under different experimental conditions

Manganese(II) catalysed cerium(IV) oxidation of arsenic(III) in aqueous sulphuric acid

902-903Manganese(II) catalysed Ce(IV) oxidation of arsenic(III) in aqueous sulphuric acid takes place with intervention of a Mn(III) species, presumably MnOH2+. The active oxidant is understood to be a Ce(IV) sulphate complex of the formula, H3Ce(SO4)

Platinum Catalysed Thallium(III) Oxidation of Vanadium(IV) in Aqueous Sulphuric Acid

255-25

Oxidation of thiosulphate by hexacyanoferrate(III) in aqueous perchloric acid medium — A kinetic and mechanistic study

357-361The kinetics of oxidation of thiosulphate by hexacyano-ferrate(III) in an aqueous perchloric acid medium has been studied spectrophotometrically by stopped flow method at 25°C. The stoichiometry is 1:1, i. e., one mole of thiosulphate consumes one mole of hexacyanoferrate(III). The reaction products are identified as Fe(CN)₆²⁻ and S₄O₆²⁻. The reaction is first order with respect to hexacyanoferrate(III) and thiosulphate concentrations. Increase in perchloric acid concentration increases the rate of reaction (order=0.40). Added products do not have any significant effect on the rate of reaction. The effect of ionic strength and dielectric constants on the reaction rate has also been studied. The active species of oxidant is indicated to be HFe(CN)₆³⁻. A suitable mechanism is proposed and the reaction constants of the different steps involved have been evaluated. Activation parameters have also been calculated with respect to the slow step of the mechanism

Oxidation of thallium(I) by permanganate in aqueous perchloric acid

190-192Permanganate oxidation of thallium(I) in aqueous perchloric acid has 2:3 stoichiometry (oxidant: reductant) and manganese(IV) and thallium(III) are the products. A clean second order kinetics is followed by the reaction with fractional dependence on [acid]. The. results are explained by a mechanism involving HMnO4 as the active oxidant species

Thallium(III) Oxidation of Oxovanadium(IV)

1075-107

Oxidation of hexacyanoferrate(II) by peroxodisulphate in aqueous perchloric acid-A kinetic and mechanistic study

1090-1094The kinetics of the reaction between hexacyanoferrate(II) and peroxodisulphate has been studied spectroscopically in perchloric acid. The reaction is first order each in peroxodisulphate and hexacyanoferrate(II) concentrations. Increase in perchloric acid concentration increases the reaction rate. The order with respect to perchloric acid concentration is less than unity. The active species of hexacyanoferrate(II) and peroxodisulphate are HFe(CN)₆³⁻ and S₂O₈²⁻ respectively. A suitable mechanism is proposed for the studied reaction. The thermodynamic quantities with respect to the first step and the activation parameters with respect to the slow step of the mechanism have been calculated. Numerical simulation with this mechanism agrees well with the experimental results