Preparation[edit]
Iron(III) oxide is a product of the oxidation of iron. It can be prepared in the laboratory by electrolyzing a solution of sodium bicarbonate, an inert electrolyte, with an iron anode:
4 Fe + 3 O2 + 2 H2O → 4 FeO(OH)
The resulting hydrated iron(III) oxide, written here as Fe(O)OH, dehydrates around 200 °C.[12][13]
2 FeO(OH) → Fe2O3 + H2O
It can also be prepared by the thermal decomposition of iron(III) hydroxide under temperature above 200 °C.
2 Fe(OH)3 → Fe2O3 + 3H2O
§Uses[edit]
§Iron industry[edit]
The overwhelming application of iron(III) oxide is as the feedstock of the steel and iron industries, e.g. the production of iron, steel, and many alloys.[13]
§Polishing[edit]
A very fine powder of ferric oxide is known as "jeweler's rouge", "red rouge", or simply rouge. It is used to put the final polish on metallic jewelry and lenses, and historically as a cosmetic. Rouge cuts more slowly than some modern polishes, such as cerium(IV) oxide, but is still used in optics fabrication and by jewelers for the superior finish it can produce. When polishing gold, the rouge slightly stains the gold, which contributes to the appearance of the finished piece. Rouge is sold as a powder, paste, laced on polishing cloths, or solid bar (with a wax or grease binder). Other polishing compounds are also often called "rouge", even when they do not contain iron oxide. Jewelers remove the residual rouge on jewelry by use of ultrasonic cleaning. Products sold as "stropping compound" are often applied to a leather strop to assist in getting a razor edge on knives, straight razors, or any other edged tool.