Iron sulfate is a chemical compound that is extremely common in nature and widely used in various fields of economic activity. There are divalent and trivalent modifications of this substance. The first variety, also called iron sulfate, is an inorganic binary non-volatile compound having the formula FeSO 4 . Externally, this chemical compound is a clear crystalline hydrate of light greenish-blue color, having a high degree of hygroscopicity and solubility in an aqueous medium. In a vacuum, FeSO 4 decomposes with high intensity; complete decomposition occurs at a temperature of about 700 ° C.
Ferrous sulfate serves as a widely used reagent, crystallizing at room temperature from solutions in the form of FeSO 4 ∙ 7H 2 O heptahydrate, which is a pale blue substance. During prolonged storage, it erodes, turning into a white powdery substance, and in the open air it gradually turns yellow due to oxidative processes. The weathering of iron sulfate is explained by the fact that in its structure there is one molecule of external sphere water, which easily leaves the crystal lattice.
Trivalent anhydrous iron sulfate is a light yellow, paramagnetic, extremely hygroscopic crystalline substance of monoclinic syngony. It is capable of forming orthorhombic and hexagonal structural modifications. Ferric sulfate crystallizes well from various solutions in the form of a variety of hydrated compounds containing up to ten water molecules. When slowly heated, it turns into an anhydrous salt, which decomposes well into hematite and sulfuric anhydrite at a temperature of about 650 ° C. Like many other salts of triply charged cations, iron sulfate forms alum, crystallizing in the form of pale purple octahedra. This substance is a good reducing agent for the Ag + ion, which has strong oxidizing properties. Ferric sulfate, hydrolysis of which is observed upon boiling the solution in which it is contained, exists in nature mainly in jarosite (mineral).
In industry, this substance is obtained mainly as a by-product at metal processing plants from various pickling solutions used to remove scale from steel products. Also, this substance can be isolated by calcining pyrites or marcasites with NaCl in air. Another method of its synthesis is the heating of iron oxide in sulfuric acid salts. In laboratory practice, this compound is isolated from Fe (OH) 2 .
Of considerable curiosity is the fact that iron sulfate was discovered on Mars in 2009 by the Spirit spacecraft, from which scientists concluded that strong oxidative processes occur on the planet's surface. Due to the very low density of this substance, the rover is so deeply bogged down in its deposits that it even touched part of the hull of the deep layers of Martian soil.
On Earth, iron sulfate, due to its ability to hydrolyze along with aluminum alum, is used as a flocculant in the process of purifying drinking water. Forming hydroxide flakes, this chemical compound adsorbs many harmful impurities. Also, this substance has been widely used in medicine, where it is used as a therapeutic and prophylactic agent for iron deficiency anemia.
In the agricultural industry, iron sulfate is used for chemical land reclamation, pest control of cultivated plants, the destruction of mosses, lichens, weeds and spores of parasitic mushrooms. In horticulture, iron sulfate is used to feed fruit trees as a catalyst for the formation of chlorophyll. The most sensitive to the lack of this substance is the apple tree, pear, plum and peach.
In industry, iron sulfate is widely used in the textile industry, where it serves as an important component of ink and various mineral inks. Also, this substance is a good wood preservative. Some so-called waste solutions of iron sulfate are processed into such insulating materials as ferron and ferrigypsum, which are a mixture of hydrates of this compound with various fillers.