Kinetics of Decomposition of Nitric Oxide at Elevated Temperatures. I. Rate Measurements in a Quartz Vessel

Abstract

The rate of thermal decomposition of nitric oxide has been measured in a quartz vessel from 872 to 1275°K. The reaction follows a second‐order rate law over the range of temperatures studied. Variations in the surface‐to‐volume ratio of the reaction vessel indicate the predominance of a heterogeneous mechanism at temperatures below 1000°K, whereas at higher temperatures a homogeneous mechanism prevails. The experimental data are interpreted on the basis of the relative contribution of the heterogeneous and homogeneous mechanisms to the over‐all kinetics. Such an analysis explains the variation in effective activation energy with temperature from a value of 21.4 kcal below 1000°K to 82 kcal above 1600°K. An intermediate temperature region exists in which both mechanisms contribute an important part to the over‐all rate.