The initial rate method in chemical kinetics: Evaluation and experimental illustration

Casado, Julio; López‐Quintela, M. Arturo; Lorenzo-Barral, Francisco M.

doi:10.1021/ed063p450

Cited by 119 publications

(98 citation statements)

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“…Because of the Hammond postulate [30], it is reasonable to suppose that the rate constant ratios (24) for the two parallel reaction sets (11), (12) and (16), (17) are not severely affected although the true rate constants may be quite different in each set.…”

Section: Discussionmentioning

confidence: 99%

“…In this study the initial rates method [17] was used for kinetic analysis. While such a method is perfectly compatible with the normal standards of experimental accuracy, in certain circumstances it offers advantages over the integral method (e.g., the presence of competitive reactions is considerably less important when the initial rates method is employed).…”

Section: ϫmentioning

confidence: 99%

“…While such a method is perfectly compatible with the normal standards of experimental accuracy, in certain circumstances it offers advantages over the integral method (e.g., the presence of competitive reactions is considerably less important when the initial rates method is employed). The initial rates were obtained by fitting the absorbance vs. time data, for a small percentage of the reaction (5% or less) [17], to a straight line, by the least-squares I ϭ 0.5 M lowed to go to completion and the residual oxidant concentration was determined spectrophotometrically. These measurements indicate that one mole of alcohol reacts with two moles of oxidant.…”

Section: ϫmentioning

confidence: 99%

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Kinetic study of ruthenium(VI)-catalyzed oxidation of 2-butanol by alkaline hexacyanoferrate(III)

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Rodrı́guez

et al. 1999

Int. J. Chem. Kinet.

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The oxidation kinetics of 2-butanol by alkaline hexacyanoferrate(III) catalyzed by sodium ruthenate has been studied spectrophotometrically. The initial rates method was used for kinetic analysis. The reaction rate shows a fractional-order in [hexacyanoferrate(III)] and [substrate] and a first-order dependence on [Ru(VI)]. The dependence on [OH Ϫ ] is rather more complicated. The kinetic data suggest a reaction mechanism involving two active catalytic species. Each one of these species forms an intermediate complex with the substrate. The attack of these complexes by hexacyanoferrate(III), in a slow step, produces ruthenium(V) complexes which are oxidized in subsequent steps to regenerate the catalyst species.

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Section: Discussionmentioning

confidence: 99%

Section: ϫmentioning

confidence: 99%

Section: ϫmentioning

confidence: 99%

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Kinetic study of ruthenium(VI)-catalyzed oxidation of 2-butanol by alkaline hexacyanoferrate(III)

Mucientes

Poblete

Rodrı́guez

et al. 1999

Int. J. Chem. Kinet.

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“…The investigation of reaction kinetics often relies on the initial rates. [2][3][4][5][6] [Also see the numerous sources and sites found by googling with the term 'initial rate method.'] The initial rate method is appropriate for the determination of kinetics of homogeneous reactions, often saving time and effort.…”

Section: Hong Yong Sohn and De-qiu Fanmentioning

confidence: 99%

“…Equation [5] can be further rearranged to obtain the molar rate of solid consumption per area of the sample as:…”

Section: An Initially Non-porous Solid Forming a Porous Product Lmentioning

confidence: 99%

On the Initial Rate of Fluid–Solid Reactions

Sohn

Fan

2017

Metall Mater Trans B

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It is argued in this paper that the initial rate should not be used for the measurement or analysis the kinetics of a fluid-solid reaction, especially for a reaction in which the effect of pore diffusion starts appearing even moderately as the reaction proceeds. Even in the absence of external mass transfer effects, it is shown in this work by rigorous mathematical analysis that the range of conditions where the initial rate represents the intrinsic kinetics is very narrow. For an initially non-porous solid in the absence of external mass transfer effects, the very initial rate should mathematically be the intrinsic rate even when pore diffusion becomes important as the reaction proceeds. However, even in this case, the range of conditions for this statement is very limited. For the reaction of an initially porous solid, the rate at time zero is already affected by pore diffusion unless its effect is negligible over the entire range of conversion. Furthermore, the initial reaction rates of porous solids reacting under large values of k/D e ratio (chemical reactivity is much greater than the capacity for pore diffusion) have an apparent rate constant of ffiffiffiffiffiffiffiffiffiffiffi ffi k Á D e p and thus pore diffusion alone does not control the initial rate no matter how large the effect of pore diffusion is overall.

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