Solid-state decomposition studies on fluoroperoxo species of transition metals. Part VI. Kinetics of isothermal decomposition of M2Zr2(O2)2F6 · 2 H2O (M = Rb+, or Cs+) |
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Authors: | GV Jere SM Kaushik |
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Institution: | Department of Chemistry, Indian Institute of Technology, New Delhi 110029 India |
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Abstract: | The decomposition of solid fluoroperoxozirconates of alkali metals, M2Zr2(O2)2F6 · 2 H2O (M = Rb+, Cs+), is carried out in vacuum under isothermal conditions. The stoichiometry of the reaction may be represented by the equation, M2Zr2(O2)2F6 · 2 H2O(S) — M2Zr2O2F6(s) + O2(g) + 2 H2 O(g) (condensed). The fractional decomposition α is determined by measuring the pressure of oxygen evolved during pyrolysis with a McLeod gauge. The α values range from 0.06 to 0.70 for the rubidium and from 0.06 to 0.79 for the caesium species in the temperature ranges 107–202°C and 101–219°C, respectively. The α—time data for both compounds show that the kinetics are deceleratory throughout the course of the decomposition reaction. In both compounds, the initial stages of decomposition are described by a unimolecular decay law, while the later stages obey a contracting volume equation at all temperatures. The activation energies from Arrhenius plots are 14.0 and 10.9 kcal mole?1 for the rubidium and 12.9 and 11.2 kcal mole?1 for the caesium compound. |
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Keywords: | To whom correspondence should be addressed |
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