The inorganic compound iron hydroxide 3 has the chemical formula Fe (OH) 2. It belongs to a number of amphoteric iron compounds in which the properties characteristic of the bases prevail. In appearance, this substance is a white crystal, which, with prolonged exposure to the open air, gradually darkens. There are options for crystals of a greenish tint. In everyday life, each substance can be observed in the form of a greenish coating on metal surfaces, which indicates the beginning of the rusting process - iron hydroxide 3 acts as one of the intermediate stages of this process.
In nature, the compound is found in the form of amakinite. This crystalline mineral, in addition to iron itself, also contains impurities of magnesium and manganese, all these substances give amakinite different shades - from yellow-green to pale green, depending on the percentage of one or another element. The hardness of the mineral is 3.5-4 units on the Mohs scale, and the density is approximately 3 g / cm³.
The physical properties of a substance should also include its extremely low solubility. When iron hydroxide 3 is heated, it decomposes.
This substance is very active and interacts with many other substances and compounds. So, for example, having the properties of a base, it enters into neutralization reactions with various acids. In particular, sulfuric acid, iron hydroxide 3 during the reaction lead to the production of iron (III) sulfate . Since this reaction can occur by conventional calcination in the open air, such an inexpensive method for the production of sulfate is used both in laboratory and in industrial conditions.
During the reaction with hydrochloric acid, its result is the formation of iron (II) chloride.
In some cases, iron hydroxide 3 may also exhibit acidic properties. For example, when interacting with a highly concentrated (concentration should be at least 50%) sodium hydroxide solution, sodium tetrahydroxoferrate (II) is obtained, which precipitates out. True, for the course of such a reaction, it is necessary to provide rather difficult conditions: the reaction must occur under conditions of a solution boiling in a nitrogen atmosphere.
As already mentioned, when heated, the substance decomposes. The result of this decomposition is iron (II) oxide , and, in addition, metallic iron and its derivatives are obtained in the form of impurities: dihelez oxide (III), whose chemical formula is Fe3O4.
How to produce iron hydroxide 3, the preparation of which is associated with its ability to react with acids? Before embarking on an experiment, it is imperative to recall the safety rules when conducting such experiments. These rules apply to all cases of handling acid-base solutions. The main thing here is to provide reliable protection and to avoid dropping drops of solutions on the mucous membranes and skin.
So, hydroxide can be obtained in the course of a reaction in which iron (III) chloride and KOH - potassium hydroxide interact. This method is the most common for the formation of insoluble bases. During the interaction of these substances, the usual metabolic reaction proceeds, resulting in a brown precipitate. This precipitate is the desired substance.
The use of iron hydroxide in industrial production is quite widespread. The most common is its use as an active substance in batteries of iron-nickel type. In addition, the compound is used in metallurgy to produce various metal alloys, as well as in galvanic production and automotive manufacturing.