Continuous flow systems. Distribution of residence times

It is widely believed that the chemical master equation has no rigorous microphysical basis, and hence no a priori claim to validity. This view is challenged here through arguments purporting to show that the chemical master equation is exact for any gas-phase chemical system that is kept well stirred and thermally equilibrated.

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A rigorous derivation of the chemical master equation

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...

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

A literature review on mechanisms and models for the coalescence process of fluid particles

A generalized treatment of gas transport in porous media is presented as developed on the basis of the ``dusty‐gas'' model, a model in which a porous medium is described as consisting of uniformly distributed, giant molecules (dust) held stationary in space. The problem is broken down into a series of special cases which involve the various combinations of gradients in composition, pressure, and temperature.Equations are given for the description of several well‐known phenomena. These include isobaric, isothermal diffusion; diffusion under the influence of a pressure gradient; Poiseuille's flow equation, including the Knudsen minimum; the Kramers—Kistemaker effect; thermal transpiration; and the effect of pressure on the thermal‐diffusion factor. The results are likewise applicable to capillaries by a suitable substitution for geometric parameters.

R. D. Present

Papers

Kinetic Theory of Gases