The average salt is iron chloride, the formula of which is FeCl3, is a compound of ferric iron with hydrochloric acid. This substance is a black-brown plate (leaflet) that shimmers and flickers in the light. There are the same leaves of a purple or greenish hue with a metallic sheen.
This compound has strong hygroscopicity, and directly in air under normal conditions it turns into a hydrate whose formula is FeCl3 • 6H2O. These yellow or tan crystals are perfectly soluble in water - at a temperature of twenty degrees in 100 grams of water, 91.9 g of anhydrous salt of iron chloride is completely dissolved.
The melting point of the substance is 309 ° C. In the chemical industry, it is produced, as a rule, in the form of an anhydrous salt or in the form of a six-molecular crystalline hydrate. In industry, iron chloride is used to produce pure polystyrene, in the production of various varnishes. In all such technologies, the reaction proceeds with the participation of phenol or ethyl cresol ether, which regulate the course of the reaction. As a rule, iron chloride is volatile and evaporates with water vapor. When stored in a humid environment, the substance spreads. This phenomenon can be observed already at 100 ° C, with a further increase in temperature and reaching 317 ° C, iron chloride iii begins to boil and evaporate, followed by decomposition. Salt prepared in this way immediately crystallizes from the gas stage and settles on the vessel. At the same time, the precipitate is so resistant that it is not even washed off with carbon tetrachloride, which also condenses on the walls of the vessel.
Iron trichloride can be obtained in a fairly simple experiment. To do this, it is necessary to act on the filings of iron with chlorine in a gaseous state. As a result of this reaction, a ferric salt will be obtained. This reaction differs from the reaction in which the active substance is hydrochloric acid.
In addition to this method, iron chloride can be obtained as a result of an oxidative reaction in which chlorine and iron dichloride - 2FeCl2 are involved. More interesting from the point of view of application is the method of producing iron trichloride by oxidation with sulfur oxide (IV).
In vapor form, iron trichloride has a structure that is almost similar to that of aluminum chloride; during this reaction, the liberation of FeCl3 molecules begins when the temperature reaches 500 ° C.
This substance is widely used as a coagulant in various water purification technologies. In the chemical industry, it is used as a catalyst in the synthesis reactions of organic compounds. Widely used in textile manufacturing.
When heated, iron chloride, upon reaching the melting point and normal atmospheric pressure, decomposes into dichloride and chlorine molecules. Being a fairly strong Lewis acid, trichloride is able to participate in reactions with other chlorides. As a result of such reactions, various salts of tetrachloro ferric acid are obtained, and when it is heated with the participation of iron (III) oxide to 350 ° C, iron oxochloride is obtained.
As a rule, salts of iron trichloride are weak oxidizing agents, although there are exceptions. For example, it oxidizes metallic copper quite easily. As a result of this reaction, soluble chlorides CuCl and CuCl2 are obtained.
Iron trichloride is used as an etching agent in the manufacture of printed circuit boards in radio engineering and zincography. As a mordant, it is indispensable in the textile industry. In industrial volumes, trichloride iron is used in water treatment technologies.
This compound is toxic, contributes to corrosive processes. Avoid getting boiling vapor of iron trichloride in the lungs.