NH4FeSO4212H2O

NH4FeSO4212H2O refers to a chemical compound that is a hydrated double salt of ammonium and iron(II) sulfate. It is commonly known as Mohr's salt, named after the German chemist Karl Friedrich Mohr. The chemical formula indicates that for every one ammonium ion (NH4+) and one iron(II) ion (Fe2+), there are two sulfate ions (SO42-) and twelve water molecules (H2O) associated with the crystal structure. Mohr's salt is typically a pale green crystalline solid. It is soluble in water, forming a pale pink solution due to the presence of the Fe2+ ion. Unlike many iron(II) salts, Mohr's salt is relatively stable in air and does not readily oxidize to iron(III) due to the presence of the sulfate ions. This stability makes it a convenient reagent for quantitative analysis, particularly in redox titrations. It is frequently used as a primary standard for standardizing solutions of oxidizing agents like potassium permanganate or potassium dichromate. The iron(II) ions in Mohr's salt are oxidized during the titration, and the endpoint is usually indicated by a color change.