43059-01-4

Hazard Information

Questions And Answer

• Physical Properties

  The anhydrous salt constitutes grayish-white rhombic crystals; hygroscopic; density 3.10 g/cm3; slightly soluble in cold water; decomposes in hot water. The nonahydrate is a yellow hexagonal crystalline substance; refractive index 1.54; density 2.10 g/cm3; hardness 2.5 Mohs; decomposes at 400°C; very soluble in water. ;

• Uses

  Iron(III) sulfate is used as a pigment; as a mordant in calico printing and dyeing textiles; in sewage treatment; as a coagulant in water purification; in pickling stainless steel; in etching aluminum; and as a catalyst. An important application of this compound is for preparing other iron(III) salts and iron alums. It also is used in pharmaceutical preparations. ;

• Reactions

  Thermal decomposition of iron(III) sulfate yields iron(III) oxide with evolution of sulfur trioxide:
  Fe2(SO4)3 → Fe2O3 + 3SO3
  Iron(III) sulfate readily forms alums with many isomorphous compounds by mixing equimolar amounts of both the salts in aqueous solutions followed by crystallization:
  Fe2(SO4)3 (aq) + (NH4)3SO4 (aq) → 2NH4Fe(SO4)2 •12H2O
  Fe2(SO4)3 (aq) + Cr2(SO4)3 (aq) → 2FeCr(SO4)3 •12H2O
  Iron(III) sulfate may be reduced to +2 oxidation state of the metal in solution in the presence of common reducing agents. For example, reaction with zinc in sulfuric acid can produce iron(II) sulfate. The molecular equation is as follows:
  Fe2(SO4)3 + Zn → 2FeSO4 + ZnSO4 ;