Oxidation of variable-valence cations with ozone: I. Behavior of ozone in nitric acid solutions

Behavior of ozone in nitric acid solutions (0.1 - 11 M) in the temperature range from approximately 0 to 95 degrees C and [O-3](s) = 5 x 10(-5)-3 x 10(-4) M was studied. Distribution of ozone between the gas phase and aqueous solution obeys the Henry's law. The rate of ozone decomposition under these conditions is proportional to the 3/2 power of ozone concentration and varies insignificantly with solution acidity: -d[O-3]/d tau = k(eff)[O-3](3/2)[H+](-1/2). The thermodynamic parameters of activation of ozone decomposition were determined as Delta G(#) = 99.2+/-0.4 and Delta H-298(#) = 80.3 +/- 4.2 kJ mol(-1). The chain mechanism of ozone decomposition in acidic solutions was presumed, with the reaction O-3 + H2O --> 20H + O-2 initiating the chain.