The mechanism of the homogeneous combination of hydrogen and oxygen

Source abstract

Abstract According to the generally accepted belief, molecules do not, in most chemical reactions, undergo transformation until they have had imparted to them by some physical agency, such as collision with another molecule, a certain critical amount of energy. This process is commonly called “activation.” Ordinarily it is governed by the energy distribution laws prevailing in a system in thermodynamic equilibrium, but in exothermic reactions a special mechanism has been shown to be possible, in which the energy set free is communicated by the molecules formed in the reaction to untransformed molecules, and immediately activates them, thereby establishing what is known as a reaction chain. In a theoretical discussion of the matter Christiansen and Kramers have called attention to the fact that these chains may be of two kinds. In the first kind each act of chemical transformation does not produce more than one molecule capable of continuing the chain; and since the chain may be interrupted by various circumstances, a “stationary” condition will be established when the number of chains starting in unit time is equal to the number which are terminated.