Verification of the Possibility of Producing Wüstite From the Decomposition of Hematite and Magnetite in the Inner Layers of the Earth

Abstract

This research aims, starting from the study of the change in the free energy of a chemical reaction, to reveal the possibility of producing one of the important oxides in the formation of the Earth's layers, especially the Earth's lower mantle. This oxide is FeO or what is name Wüstite, which can be produced from the decomposition of each of Hematite (Fe₂O₃), Magnetite (Fe₃O₄). This is done by calculating and taking into account three important hypotheses, which are the change and stability with the change in temperature from 0 to 7000 °C for each of the thermodynamic parameters, which are; heat capacity at constant pressure, enthalpy and entropy of reaction. What we found from it; that our study indicates that the production of this oxide through the decomposition of hematite occurs at all depths of the Earth, starting from the Earth's crust. While its production from the decomposition of magnetite continues regardless of the depth of the Earth, but this is mostly from specific depths. As long as the three parameters do not change with the change in temperature, this production begins approximately from the middle of the Earth's lower mantle and precisely from the depth 1497.3 km, but as long as the heat capacity does not change with constant pressure, production begins from the middle of the Earth's crust, and precisely from the depth 27.93 km. Finally, and with the change of all parameters together with the change in temperature, this begins from the depth 77.89 km which corresponds to the beginning of the lithosphere region.