Ammonium iron(II) sulfate hexahydrate ≥98%

Ammonium iron(II) sulfate is a light green to blue crystalline powder, which dissolves readily in water, but is insoluble in ethanol and acetone. The salt melts and begins to decompose at 100 °C.Ammonium iron(II) sulfate is a double salt of iron sulfate and ammonium sulfate and is made by dissolving equimolar iron(II) sulfate and ammonium sulfate in water and crystallizing the product.

Ammonium iron(II) sulfate is widely used as a source of Fe²⁺ ions because of its high solubility in water and because it oxidizes much more slowly in air than other ferrous salts like iron(II) sulfate. Consequently, the reagent finds broad applications from analytical titrations to aqueous redox chemistry as a reducing agent. Researchers often use ammonium iron(II) sulfate as a source of Fe²⁺ to synthesize iron-containing nanoparticles. For example, to synthesize magnetite (Fe₃O₄) nanoparticles, researchers co-precipitate aqueous solutions of ammonium iron(II) sulfate with a source of Fe³⁺, like FeCl₃ or NH₄Fe(SO₄)_{2 .} Ammonium iron(II) sulfate also serves as a precursor in the synthesis of iron(III) oxide-hydroxide (FeOOH) nanosheets and as reagents to dope metal oxide-hydroxide nanosheets with iron. Ammonium iron(II) sulfate is also well-suited to make olivine LiFePO₄ by the co-precipitation method. In this method, aqueous solutions of ammonium iron(II) sulfate are mixed with ammonium phosphate and co-precipitated with lithium hydroxide. One advantage of this synthetic strategy is that it enables the in-situ formation of nanocomposites like LiFePO₄/graphene.