Formation of nitrous acid in a gas-phase stirred flow reactor

The gas-phase reaction between nitric oxide, nitrogen dioxide and water vapour to form nitrous acid has been studied in a stirred flow Pyrex reactor in the temperature range 298.2–328.2 K. Mixing in the reactor was promoted solely by the turbulent inlet jet and a close approximation to ideality was obtained. The reaction was followed by photometric measurement of the concentration of nitrogen dioxide in the reactor. Comparison of the results obtained at 298.2 K with those of previous workers confirms the suggested second-order dependence on water vapour pressure and shows the reaction to be heterogeneous.