Дигидрат хлорида железа

Description

Iron(II) chloride dihydrate is a crystalline hydrate of divalent iron dichloride with two water molecules, a form intermediate in degree of hydration between anhydrous iron(II) chloride and its tetrahydrate. Like other iron(II) chloride hydrates, the compound is sensitive to air, moisture and light and is prone to gradual oxidation of iron(II) to iron(III) when stored for long periods in open containers, and is also incompatible with strong oxidizing agents and most common metals. The fixed content of water of crystallization (two molecules per formula unit) distinguishes this form from the tetrahydrate and makes it convenient for precise dosing by weight when preparing solutions of a given concentration, when a moisture content in the initial reagent that is intermediate between the anhydrous salt and the tetrahydrate is required.

Basic Attributes

• CAS number: 16399-77-2
• Chemical formula: Cl2Fe,2H2O
• Molecular Weight: 162.78156
• PSA specifications: 40.46000
• XLogP3: 1.02290

Synonyms

Ferric chloride (FeCl2), dihydrate; ferrous dichloride dihydrate; ferric chloride dihydrate; iron(II) chloride dihydrate; FeCl2 2H2O.

Scope of application

It is used in inorganic synthesis as a source of Fe²⁺ ion, as well as in laboratory practice and water treatment - similar to other hydrated forms of iron(II) chloride, with the difference that the content of water of crystallization in the dihydrate is less than in the tetrahydrate, which is important to take into account when recalculating the mass fraction of active iron in the reagent.

Series of iron(II) chloride hydrates

Iron(II) chloride forms several crystalline hydrates with different numbers of water molecules per formula unit - from anhydrous salt to tetrahydrate, with the dihydrate occupying an intermediate position in this series. When hydrates are heated, a gradual loss of water of crystallization occurs, and in an atmosphere that does not contain moisture, the dihydrate is able to dehydrate further - down to anhydrous salt; on the contrary, in a humid atmosphere it is capable of adding additional water to higher hydrates. The choice of a specific hydrate form for a practical task is determined by the convenience of dosage, storage stability and the required active iron content in the final reagent solution.

Storage and transportation

Store in the original tightly closed container, protected from light, in a cool, dry, ventilated area, away from strong oxidizing agents and common metals. There are no special UN transport codes and GHS phrases for this hydrate form recorded in the passport - when transporting the batch, take into account the classification applicable to related iron(II) chloride hydrates (corrosive substance of class 8). When working with the substance, use gloves and safety glasses, avoiding inhalation of dust and contact with skin and mucous membranes, as with any ferrous iron compound that is irritating to the skin, eyes and respiratory tract.