Rate Constants for the Removal of Radicals at the Wall in Linearly Branched or Terminated Chain Reactions

Abstract

The effect of the removal of radicals by the wall is described for reacting systems linear in radical concentration. Exact expressions are derived for the surface rate constant ksurf, defined in terms of the mean radical concentration, η, in cylindrical and spherical vessels. A unified description of ksurf is given for systems which are initiated in the gas-phase or at the wall, and which are chain branched (either in slow reacting or explosion boundary condition), gas-phase chain terminated or straight chains terminated at the wall.

Approximations are given for these exact expressions in the case of cylindrical vessels, and their accuracy and range of application are indicated.

An alternative and exact method of expressing these rate constants is described whereby ksurf is cast into the forms [graphics omitted]. The appropriate values of Kc and Ks, slowly varying “constants”, are given.