Ammonium iron(II) sulfate, also known as Mohr’s salt, is a chemical compound with the formula (NH4)2Fe(SO4)2·6H2O. It is a double salt containing two different cations: ammonium ions (NH4+) and iron(II) ions (Fe2+), as well as sulfate ions (SO4^2-) and water molecules (H2O).

Here are some key points about ammonium iron(II) sulfate:

1. Formula: The chemical formula (NH4)2Fe(SO4)2·6H2O represents the composition of ammonium iron(II) sulfate. The ammonium ion (NH4+) is a positively charged polyatomic ion, while the iron(II) ion (Fe2+) is a divalent cation.
2. Preparation: Ammonium iron(II) sulfate is commonly prepared by dissolving ferrous sulfate (FeSO4) in a solution of ammonium sulfate ((NH4)2SO4) with subsequent crystallization.
3. Appearance: In its pure form, ammonium iron(II) sulfate appears as pale green crystals with a characteristic metallic taste.
4. Solubility: Ammonium iron(II) sulfate is soluble in water, and its solubility increases with temperature.
5. Uses: Ammonium iron(II) sulfate is used as a reagent in analytical chemistry to standardize potassium dichromate solutions in redox titrations. It is also used as a reducing agent in certain chemical reactions.
6. Oxidation State: The iron ion in ammonium iron(II) sulfate has a +2 oxidation state, which is why the compound is also referred to as iron(II) sulfate or ferrous sulfate.

Ammonium iron(II) sulfate is a versatile compound with various applications in analytical chemistry and as a reducing agent. It is essential to handle and store this compound appropriately and in accordance with safety protocols due to its potential hazards and reactivity.