The objects for the studies of this paper are iron sulfates where the iron has second or third valences and where coordination
between iron, sulfur and oxygen is different. DSC technique is used to investigate thermal stability and enthalpy changes
when iron compounds are treated in different gas medium. The main objective is to compare thermal stability and enthalpy of
iron oxy-sulphate, often detected as an intermediate, with commonly known iron sulphates.
DSC curves of samples with equal mass under different gas medium, determining different partial pressure of oxygen in the
gas phase, are the base for comparative study of the sample’s thermal properties. Obtained different values of the enthalpy
and mass losses and kinetic parameters demonstrate that the stability of oxy-sulphate strongly depended on the value of oxygen
partial pressure in the gas phase.
The new evidences from the experimental study help to propose the mechanism of the decomposition and to compare some of the
iron sulphates properties.