Ferric Chloride

Iron(III) chloride is the inorganic compound with the formula (FeCl
3
). Also called ferric chloride, it is a common compound of iron in the +3 oxidation state. The anhydrous compound is a crystalline solid with a melting point of 307.6 °C. The color depends on the viewing angle: by reflected light the crystals appear dark green, but by transmitted light they appear purple-red.

Anhydrous

Anhydrous iron(III) chloride has the BiI3 structure, with octahedral Fe(III) centres interconnected by two-coordinate chloride ligands.

Iron(III) chloride has a relatively low melting point and boils at around 315 °C. The vapour consists of the dimer Fe
2Cl
6
 (cf. aluminium chloride) which increasingly dissociates into the monomeric FeCl
3
 (with D3h point group molecular symmetry) at higher temperature, in competition with its reversible decomposition to give iron(II) chloride and chlorine gas.

Hydrates

In addition to the anhydrous material, ferric chloride forms four hydrates. All forms of iron(III) chloride feature two or more chlorides as ligands, and three hydrates feature FeCl4.

  • hexahydrate: FeCl3.6H2O has the structural formula trans-[Fe(H2O)4Cl2]Cl.2H2O
  • FeCl3.2.5H2O has the structural formula cis-[Fe(H2O)4Cl2][FeCl4].H2O.
  • dihydrate: FeCl3.2H2O has the structural formula trans-[Fe(H2O)4Cl2][FeCl4].
  • FeCl3.3.5H2O has the structural formula cis-[FeCl2(H2O)4][FeCl4].3H2O.
Description

Aqueous solution

Aqueous solutions of ferric chloride are characteristically yellow, in contrast to the pale pink solutions of [Fe(H2O)6]3+. According to spectroscopic measurements, the main species in aqueous solutions of ferric chloride are the octahedral complex [FeCl2(H2O)4]+ (stereochemistry unspecified) and the tetrahedral [FeCl4]

Reviews (0)

Reviews

There are no reviews yet.

Be the first to review “Ferric Chloride”