Nomenclature
The descriptor hydrated or anhydrous is used when referring to iron(III) chloride, to distinguish between the two common forms. The hexahydrate is usually given as the simplified empirical formula FeCl3⋅6H2O. It may also be given as trans-Cl⋅2H2O and the systematic name tetraaquadichloroiron(III) chloride dihydrate, which more clearly represents its structure.
Read more about this topic: Iron(III) Chloride