Kinetic features of autocatalytic decomposition of two crystalline phases of CaO2 2H2O2

The decomposition kinetics of two crystalline phases of CaO 2 . 2H 2 O 2 containing an impurity of the hydrogen peroxide mother solution to yield calcium peroxide, water, and oxygen were studied volumetrically under wet conditions at temperatures from 25 to 45°C. S-shaped oxygen accumulation curves typical of an autocatalytic process were obtained. The reaction rate was significantly affected by the history of the starting crystals but was independent of the crystal structure type. The crystals isolated from the solution at 40°C decomposed about four times as rapidly as the crystals isolated at -20°C. The experimental data were processed in terms of a kinetic model in which the autocatalytic character of the reaction was explained by the increasing water amount on the surface of the crystalline powder. The rate constants of intermediate reaction stages and some other kinetic parameters were calculated.