Description
Molecular weight: 162.2 g/mol
pH: 1-2
Ferrous chloride III 40% is a chemical substance that contains 40% iron chloride III (FeCl3) in an aqueous solution. It is a yellowish-brown liquid. Iron chloride III itself is an inorganic chemical compound, a salt of hydrochloric acid and iron in the third oxidation state. It is a substance with corrosive properties, especially in the presence of water and acts as an oxidant. In solutions, it can act as an electrolyte, which consequently accelerates electromechanical corrosion in metals such as steel. Iron (III) chloride solution is mainly used as a coagulant in water purification processes, especially in sewage treatment plants and drinking water treatment. It removes organic and inorganic impurities by causing particle aggregation, which facilitates their subsequent removal. Iron chloride III solution is also used in some industrial processes, such as the production of pigments or chemical syntheses. It is classified as a dangerous material with the number UN 1760 according to the ADR regulations.
To obtain a solution of iron (III) chloride 40%, it is necessary to first obtain iron (III) chloride. On an industrial scale, the direct reaction of iron with chlorine is most often used. It takes place in high-temperature reaction furnaces (200-300 ° C), where iron reacts with chlorine gas. Since this is an exothermic process, special furnaces and cooling systems are used to maintain a stable temperature. To avoid the formation of iron (II) chloride (FeCl₂) instead of iron (III) chloride, an excess of chlorine is used and a higher temperature is maintained, ensuring complete oxidation of the iron. The obtained iron (III) chloride is in gaseous form, so is later condensed into a liquid or solid form. This is done in coolers, from where the product is transported to storage tanks. A less common method of obtaining this substance is the oxidation of iron (II) chloride by chlorine gas or a strong oxidizing agent. This process works well when iron(II) chloride is available as a byproduct of other industrial processes. Another less common method is the reaction of iron(III) oxide with hydrochloric acid (HCl). The byproduct is water. This method is sometimes used when iron(III) oxide is available as a waste product. The reaction takes place at elevated temperatures, and the resulting FeCl₃ solution can be concentrated or solidified. The obtained iron(III) chloride can be converted into a solution using distilled water. A small amount of hydrochloric acid (HCl) is sometimes added to reduce hydrolysis and ensure solution stability.
Iron(II) chloride is a reactive compound with oxidizing properties, so it enters redox reactions with metals. It also hydrolyzes in water to form an acidic solution. In reactions with bases, it forms iron(III) hydroxide, which is an insoluble brown precipitate. Iron(III) chloride can also react with ammonia (NH₃) to form ammonia complexes or iron(III) hydroxide, as well as with some acids, such as sulfuric acid, to form iron(III) sulfate. FeCl₃ is also used to etch metals (e.g. copper). This reaction is used in the electronics industry to etch printed circuit boards.
