Iron oxide, a ferrous oxide FeO, two iron oxide FeO2, ferric oxide Fe2O3, iron oxide Fe3O4, ferrous oxide, also known as an iron oxide, black powder, melting point is 1369 ± 1 ℃, relative density 5.7, dissolved in acid, insoluble in water and alkaline solution. Very unstable, easily oxidized to ferric oxide; heated in the air are rapidly oxidized into iron oxide. Conditions in the absence of air, heated by the ferrous oxalate to the system. The main pigment used to make glass. Reddish brown iron oxide (red) color or black powder, commonly known as red iron, melting point 1565 ℃, the relative density of 5.24. In nature in the form of hematite, with gender, with acid generating Fe (Ⅲ) salt, with the strong base effect was [Fe (OH) 6] 3 -. In the alkali medium has some reduction can be oxidized by strong oxidants. Ferric oxide is insoluble in water, or water works. Burning of ferrous sulfate, iron oxalate, iron oxide can be obtained, it can also be calcined pyrite in the air to the system. It is often used for paint, polishing agent, catalyst and Pink and so on. Black iron oxide crystals, heated to the melting point (1594 ± 5 ​​℃) while decomposition, the relative density of 5.18, with good magnetic properties, it is also known as "magnetic iron oxide." Magnetite is the main component of natural products, humid conditions in the air easily oxidized into ferric oxide. Insoluble in water, soluble in acid. Modern tests show that it is actually a mixed valence state of iron compounds, chemical formula should be Fe2Fe3 [Fe3O4]. Due to Fe2 + in magnetite and Fe3 + in octahedral sites is essentially disordered arrangement, the electrons in the oxidation state of iron between the two shift rapidly, so the solid iron oxide has excellent electrical conductivity. Heated by the steam iron, or iron oxide at 400 ℃ can be obtained by hydrogen reduction of iron oxide. Iron oxide pigments and polishing agent used to do. Magnetic iron oxide can be used to make recordings, video tapes and telecommunications equipment. Second, iron oxide (FeO2) is dark green thick oil-like liquid. Melting point -25 ℃, boiling point 170 ℃. A char, rather than smell. Miscible with water. Acidic aqueous solution. 1, two water-soluble acidic iron oxides. With water, alkali reaction.