Thermal Decomposition of Nitrocompounds in Shock Waves. IV: Decomposition of Nitric Acid

Abstract

Abstract The thermal decomposition of nitric acid highly diluted in Ar has been studied in shock waves at 890 < T < 1200 K and 8.0 · 10 −6 < [Ar] < 3.2 · 10 −4 mol cm −3 . Concentration profiles of HNO 3 , NO 2 , and NO 3 have been monitored. The rate constants of the unimolecular decomposition of HNO 3 and the subsequent reaction OH + HNO 3 can be determined directly. The results for the unimolecular decay and low temperature data of the combination reaction of HO and NO 2 have been combined to derive expressions for the rate constants in the range between room temperature and 1200K. A reaction mechanism which accounts for the observed concentration profiles is discussed.