| Abstract: | Partial reduction of iron(III) oxides with hydrogen in the presence of a platinum catalyst leads to an equilibrium state after 4–20 h. From the measured Eh, pH, and Fe2+ concentration conditional standard potentials can be calculated using the formula Eo (volt) = Eh + 0.059 lg(Fe2+) + 0.18 pH which indicate the stability of Fe oxides against reduction. The reduceability decreases following the order ferrihydrite > lepidocrocite > hematite > goethite. The difference between hematite and goethite was more pronounced than that predicted from thermodynamic data. |
