Triiron Tetraoxide The Only Iron Compound That Can Be Magnetized
triiron tetraoxide is the only iron compound that can be magnetized in secondary school. Iron oxide contains Fe 2+ and Fe 3+. X-ray diffraction experiments show that ferric oxide has a trans spinel structure, and there is no ferrite ion FeO₂²- in the crystal. Iron oxide, also known as magnetic iron oxide, iron oxide black, magnets, magnets, magnets, natural mineral types for the magnetite. Iron in the iron oxide has two kinds of valence, for the trans spinel structure, that is, [Fe Ⅲ] t [Fe ⅢFe Ⅱ] oO₄, oxygen is the most dense cubic. In addition, iron oxide or conductor, because in the magnetite because Fe 2+ and Fe 3+ in the octahedral position is basically disorderly arrangement of electrons in the iron between the two oxidation state of the rapid transfer, So the iron oxide solid has excellent conductivity.
Hydrogen reduction of α-Fe2O3
The high purity fine powder α-Fe2O3 into the disk, the powder layer should not be too thick. After the plate is placed in the reaction tube, the high purity nitrogen is passed to completely replace the air. And then through the gas cylinder slowly into the water saturated with hydrogen. The heating temperature is suitably from 300 to 400 ° C (e.g., 330 ° C). (Usually 1 ~ 3h) after cooling, stop sending hydrogen, and then replaced with nitrogen, remove the sample. Water vapor is insufficient, heating temperature is too high or excessive reduction will produce FeO, it must be noted. Improve the temperature of the gas cylinder can increase the amount of water vapor (40 ~ 60 ℃ more appropriate). Acety-like α-FeO (OH) as the starting material by heating dehydration was α-Fe2O3. With this α-Fe2O3 can be obtained needle-like iron oxide particles. Black recording tape is to use this iron oxide as a tape recording media.
The iron and sulfuric acid reaction of ferrous sulfate, and then add caustic soda and ferric oxide at 95 ~ 105 ℃ for the reaction of the formation of iron oxide, by filtration, drying, crushing iron oxide.
Slow oxidation of ferrous hydroxide
When the aqueous solution containing ferrous hydroxide precipitates is heated to 70 ° C or higher and slow oxidation is carried out, it is possible to obtain a tetra-iron oxide powder composed of substantially uniform octahedral or cubic single crystal particles having a length of about 0.2 μm. It is also possible to use air bubbles as a means of oxidation. It is also possible to use an oxidizing agent like KNO3.
In the case of skilled operation, iron oxide can be obtained by chemical composition of Fe3.00O4.00. Harber method is used to add 220 g of 20% aqueous ammonia to 2.2 L of FeSO4.7H2O aqueous solution and boil under the condition of breaking air (can be filled with capillary Round bottom flask), and a concentrated aqueous solution containing 25.5 g of KNO3 was added to the boiling.
Ferrous sulfate solution plus alkali oxidation or iron salt and ferrous salt solution by a certain percentage of mixed and added alkali precipitation in the system.