Gas-Phase Rate Constant Measurements for Reactions of Ozone with Hydrazines

摘要

Measurements have been made of the reactions between ozone and hydrazine (HZ), monomethylhydrazine (MMH) and unsymmetrical dimethylhydrazine (UDMH). Measurements were carried out, at room temperature, under pseudo-first- order conditions (hydrazines in excess), in a flow system designed to minimize diffusion limitations and wall reactions. Second-order rate constants were measured for each of the reactions. Measured values for the reactions of ozone with HZ, MMH and UDMH are 3.4 + or - 0.4 x 10(exp -15) 4.5 + or - 0.5 x 10(exp - 14) and 5.5 + or - 1.3 x 10(exp -14) cu cm/molecule/sec, respectively. These values are compared to other measurements for gas-phase and aqueous-phase reactions. In addition, use of simple dispersion models suggests that these rate constants are sufficiently high that reactions with ambient 50 ppb levels of ozone will be important in the atmosphere. Such reactions could significantly limit transport of a hydrazine(s) containing spill cloud from an accidental spill site. Application of this chemistry to sophisticated computer spill models that are being developed is discussed.