Kinetics of Reaction Between Hydroxysemicarbazide and HNO₂ in Perchloric Acid Solution

The kinetics of reaction between HNO₂ and hydroxysemicarbazide in perchloric acid solution was studied.The rate equation is found to be －dc(HNO₂)/dt=kc(HNO2)c^0.25(HSC)c^0.42(H⁺), where k ＝(1.05±0.05) (mol/L)^－0.67•s^-1 at 1.0 ℃. The activation energy is found to be (73.1±3.0) kJ/mol. Effects of c(HSC), c(H⁺), ionic strength and temperature on reduction rate of HNO₂ were investigated. The results show that HNO₂ can be rapidly reduced by HSC under usual conditions. The reaction rate can be accelerated by increasing the concentration of HSC, acidity, ionic strength and reaction temperature. The influence of ClO₄^- on reaction rate is negligible.