The relationship between the structures of Cu(II) complexes and their chemical transformations

Abstract

The paper reports an attempt to correlate the structures of hydrates of copper(II) sulphate with some characteristic features of the kinetics of their thermal decompositions. Non-isothermal thermogravimetric measurements were employed to obtain values of experimental activation energy and entropy for the dehydration of CuSO4 · 5 H2O, CuSO4 · 3 H2O and CuSO4 · H2O. The values ofE * andΔS * for the dehydration of CuSO4 · 3 H2O were found to be only little affected by the mode of preparation of this compound. On the other hand, the values ofE * andΔS * for the dehydration of CuSO4 · ·H2O are strongly dependent on whether this compound was prepared by thermal decomposition of CuSO4 · 5 H2O or CuSO4 · 3 H2O, or by crystallization from solution. As regards the crystalline hydrates of copper(II) sulphate, the greatest energetic hindrance for dehydration was observed for CuSO4 · 3 H2O. The experimental results are also discussed with respect to the present opinions concerning the possibilities of using thermal analyses to obtain information on the relationship between the structures and reactivities of solids.