MECHANISMS OF SELECTED SOLID-STATE DECOMPOSITIONS - ASPECTS OF THE INTERPRETATION AND THEORETICAL EXPLANATION OF EXPERIMENTAL-OBSERVATIONS

The use of kinetic and microscopic observations in the formulation of realistic and meaningful mechanisms for thermal reactions of initially solid compounds is discussed in general and illustrated through references to particular rate processes. The value of using chemical principles to characterize reaction geometry and interface chemistry for reactions proceeding through the advance of an active reactant/product zone is discussed. The possibility that chemical changes in initially crystalline material may proceed with melting is considered through references to systems in which the detection of the liquid phase is difficult. The importance of characterizing the reactant, the products and any intermediates, with references to their chemical properties, is discussed. Trends of behavioural similarities are considered in groups of rate processes involving related reactants. It is concluded that the most reliable theoretical deductions for any reaction are based on complementary types of experimental measurements and observations. Some reactions, formerly regarded as occurring in the solid state, are now identified as involving the essential participation of a liquid or a melt.