Photoelectric Observation of the Rate of Dissociation of Dinitrogen Tetroxide Behind a Shock Wave

Year: 1952 DOI: 10.7907/63P4-AF03
An experimental method has been developed in which a shock wave is used to heat a gas by definite amount in a time short compared to the rate of adjustment of the gas to the new temperature. The rate of attainment of the new thermal equilibrium is then followed photoelectrically. The apparatus described here can be used to study reactions with half times as short as 10⁻⁵ seconds.

By this method the rate of dissociation of dinitrogen tetroxide in the presence of a large excess of nitrogen has been studied over a 48 degree temperature range and with an eight fold variation in total pressure. The results indicate that dissociation is a unimolecular reaction, near its second order limit at one atmosphere pressure, and approaching a first order limit at higher pressures.