Influence of acidity on the oxidation rate of nitrous acid by hydrogen peroxide

The oxidation of nitrous acid by hydrogen peroxide according to the global reaction: HNO2 + H2O2 --> HNO3 + H2O has been studied in a batch vessel. Variations with time of nitrite and nitrate ions concentrations have been determined by capillary electrophoresis. The oxidation of HNO2 by H2O2 is known to be catalyzed by hydrogen ions [1,2,3] and is a very complex reaction involving numerous steps. At 20 degrees C, in the range of concentrations investigated in this work ([H3O+]: 6.7 10(-5)-2.4 10(-2) ions/l; [H2O2]: 4.3 10(-5)-1.3 10(-2) mol/l; [HNO2]: 6.0 10(-5)-1.7 10(-3) mol/l), the rate law for the oxidation process was found to be of the form: v=-d[H2O2]/dt=k[H2O+][H2O2][HNO2] which is consistent with previous studies: An average value of the kinetic constant k has been found for all the pH rang covered here: k=3012 l(2)/mol(2)/s.