Reaction Kinetics of Monomethylhydrazine With Nitrous Acid in Perchloric Acid Solution

The oxidation of monomethylhydrazine(MMH) by nitrous acid was researched in perchloric acid solution with spectrophotometry. The rate equation has been determined as follows: ：-dc (HNO₂)/dt=kc (H⁺)^0.9c (MMH) ^1.1c (HNO₂)。k is (46.0±2.7) L²/(mol²•s) with the initial perchlorate concentration of 0.50 mol/L at the temperature of 4.5 ℃. The corresponding activation energy of the reaction is (42.4±0.1) kJ/mol. The results indicate that oxidation of mono-methylhydrazine(MMH) by nitrous acid is fast. The higher concentration of MMH can accelerate the reduction process of nitrous acid. Higher acidity can also speed up the reduction of nitrous acid.