Oxyacid metal salts, decompositions

This chapter considers together the thermal decompositions of metal salts of inorganic oxyacids. The decompositions of ammonium salts of these oxyacids (and other anions) are discussed in Chapter 15. The decomposition of potassium permanganate is considered first because it represents one of the earliest solid state reactions that was subjected to detailed mechanistic investigation. Substantial interest in the reaction has continued and has been extended to other metal permanganates. 

The kinetic behaviour of metal salts of oxyacids may be influenced by water of crystallization. Where complete-dehydration precedes decomposition, the anhydrous material is the product of a previous rate process and may have undergone recrystallization. If water is not effectively removed, there may at higher temperature be the transient formation of a melt prior to decomposition. The usual problems attend the identification of partial or transient liquefaction of the reactant in the mechanistic interpretation of kinetic data. 

The activation of persulfates by various reductant viz. metals, oxidizable metals, metal complexes, salts of various oxyacid of sulfur, hydroxylamine, hydrazine, thiol, polyhydric phenols, etc. has been reported [36-38]. Bertlett and Colman [39] investigated the effect of methanol on the decomposition of persulfates and proposed the following mechanism. 

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