Chemical kinetics

About: Chemical kinetics is a research topic. Over the lifetime, 10614 publications have been published within this topic receiving 313446 citations. The topic is also known as: reaction kinetics.

Exchange Reactions with Activation Energy. I. Simple Barrier Potential for (H, H2)

Abstract: A quasiclassical procedure for the examination of the collision dynamics of atom—diatomic‐molecule reactions with activation energy is introduced. By means of Monte Carlo averages over a large number of appropriately chosen three‐dimensional classical trajectories, the total reaction cross section (Sr) and other reaction attributes can be determined as a function of the initial relative velocity (Vr) and the initial molecular rotation‐vibration state (J, ν).The method is applied to the exchange reaction resulting from a hydrogen atom and a hydrogen molecule moving on a simple barrier potential of the London—Eyring—Polanyi—Sato type. It is found that Sr is a monotonically increasing function of relative velocity that rises smoothly from a threshold at ∼0.9×106 cm/sec to its asymptotic value of ∼4.5a02 at ∼1.8×106 cm/sec. The zero‐point vibrational energy of the molecule contributes to the energy required for reaction, but the rotational energy does not. The reaction probability, which depends on VR, ν, and...

On the mechanism of low-temperature water gas shift reaction on copper.

Abstract: Periodic, self-consistent density functional theory (DFT-GGA) calculations are used to investigate the water gas shift reaction (WGSR) mechanism on Cu(111). The thermochemistry and activation energy barriers for all the elementary steps of the commonly accepted redox mechanism, involving complete water activation to atomic oxygen, are presented. Through our calculations, we identify carboxyl, a new reactive intermediate, which plays a central role in WGSR on Cu(111). The thermochemistry and activation energy barriers of the elementary steps of a new reaction path, involving carboxyl, are studied. A detailed DFT-based microkinetic model of experimental reaction rates, accounting for both the previous and the new WGSR mechanism show that, under relevant experimental conditions, (1) the carboxyl-mediated route is the dominant path, and (2) the initial hydrogen abstraction from water is the rate-limiting step. Formate is a stable “spectator” species, formed predominantly through CO2 hydrogenation. In addition...

Chemical kinetics and reaction mechanisms

Abstract: Reactions and reaction rates reactions with a simple kinetic form reversible and concurrent reactions consecutive reactions - the steady state and other approximations consecutive mechanisms - intermediates and numerical solutions deduction of reaction mechanisms transition state theory and microscopic reversibility chain reactions and oscillating reactions reactions in solution extrakinetic probes of mechanism reactions at extreme rates.

Fractal reaction kinetics.

Abstract: Classical reaction kinetics has been found to be unsatisfactory when the reactants are spatially constrained on the microscopic level by either walls, phase boundaries, or force fields. Recently discovered theories of heterogeneous reaction kinetics have dramatic consequences, such as fractal orders for elementary reactions, self-ordering and self-unmixing of reactants, and rate coefficients with temporal "memories." The new theories were needed to explain the results of experiments and supercomputer simulations of reactions that were confined to low dimensions or fractal dimensions or both. Among the practical examples of "fractal-like kinetics" are chemical reactions in pores of membranes, excitation trapping in molecular aggregates, exciton fusion in composite materials, and charge recombination in colloids and clouds.