Reactions in gases can be brought about thermally, photochemically and electrically, as well as by the passage of α-particles, which may be regarded as a special case of the electrical method. There is a good deal to be said for the view that in certain simple kinds of thermal reaction the molecules are activated by impacts of sufficient kinetic energy. No connection, however, appears to exist between the mechanism of thermal activation and that of photochemical activation. Energy imparted to electrons by light quanta is uneconomically employed as far as chemical effect is concerned, and the quanta of photochemically active light are usually much larger than the thermal energy of activation. It seemed interesting to inquire whether any connection could be found between the electrical and thermal mechanisms. Acertain general parallelism might perhaps be expected in some cases, since it is quite plausible to assume that, in an electric discharge, reactions may take place by collision of fast ions with other molecules. This is not altogether unlike the collision of two molecules with large kinetic energies in a thermal reaction. The present investigation was carried out to compare the rates at which two reactions take place in a discharge tube—allowing, as far as possible, for differences in the conductivity of the gases involved—and to see whether the results agreed in a general way with what might be expected from the known thermal reactions. Nitrous oxide and ammonia were chosen for experiment, the thermal decomposition of nitrous oxide being known to occur much more readily than that of ammonia.
The relative stability of nitrous oxide and ammonia in electric discharge