Kinetics and Mechanism of the Decomposition
of Moist CaO₂ 2H₂O₂ Crystals

A. I. Karelin*, V. A. Tarasenko**, D. G. Lemesheva***, and N. F. Gladyshev****

* Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka,
Moscow oblast, 142432 Russia

** Institute of Energy Problems of Chemical Physics, Russian Academy of Sciences,
Chernogolovka, Moscow oblast, 142432 Russia

*** Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences,
Leninskii pr. 31, Moscow, 117907 Russia

**** Research Institute of Chemistry, Tambov, Russia

Received December 30, 1999

Abstract—The kinetics of oxygen accumulation during an isothermal dissociation of peroxide CaO₂ · 2H₂O₂
crystals with an admixture of a hydrogen peroxide mother liquor at temperatures in the range of 25–45°C are
studied volumetrically. The reaction CaO₂ · 2H₂O₂ CaO₂ + 2H₂O + O₂ develops in the moist substance as
an autocatalytic reaction, as evidenced by S-shaped rate curves of oxygen accumulation. The mean activation
energy of the process is E = 79.4 ± 2.5 kJ/mol. The kinetics of the reaction are satisfactorily described by two
simultaneous differential equations, which refer to the two stages involved: CaO₂ · 2H₂O₂ + 2H₂O CaO₂+
2H₂O₂ + 2H₂O (1) and 2H₂O₂ 2H₂O + O₂ (2). The rate constants for stages (1) and (2) are calculated.
Stage(2) is realized during induction, hastening, and retardation periods; stage (1), during the hastening period.
The reason behind the development of the autocatalytic reaction is a variable, increasing amount of moisture
on crystal surfaces. In terms of the classification of chemical reactions of solids, the reaction in question is cat-
egorized as a solid–liquid reaction.

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