Iron Sulfate: Properties, Uses, and Applications Iron sulfate, also known as ferrous sulfate, is an inorganic salt with the chemical formula FeSO₄. It exists in several hydrated forms, with the most common being ferrous sulfate heptahydrate (FeSO₄·7H₂O), a blue-green crystalline solid. Anhydrous iron sulfate is a white powder, while the monohydrate form (FeSO₄·H₂O) appears as a pale yellow solid. Chemical and Physical Properties Iron sulfate is highly soluble in water, producing a light green solution due to the presence of ferrous (Fe²⁺) ions. It oxidizes slowly in moist air, forming ferric sulfate (Fe₂(SO₄)₃), which appears brownish-yellow. When heated, the heptahydrate loses water molecules, eventually decomposing to iron(III) oxide (Fe₂O₃), sulfur dioxide (SO₂), and sulfur trioxide (SO₃). Production Iron sulfate is primarily obtained as a byproduct of steel manufacturing, where sulfuric acid is used to remove rust from iron or steel surfaces. It can also be produced by reacting iron with sulfuric acid: \[ \text{Fe} + \text{H}_2\text{SO}_4 \rightarrow \text{FeSO}_4 + \text{H}_2 \] Applications 1. Agriculture - Iron sulfate is widely used as a soil amendment to correct iron deficiencies in plants, particularly in alkaline soils where iron becomes unavailable. - It also serves as a moss killer in lawns and helps lower soil pH in gardens. 2. Water Treatment - It acts as a coagulant in wastewater treatment, removing phosphates and heavy metals by forming insoluble precipitates. 3. Medical Use - Ferrous sulfate is an essential iron supplement for treating iron-deficiency anemia. It is available in tablet or liquid form. 4. Industrial Applications - Used in the production of iron gall ink, a traditional writing ink. - Serves as a reducing agent in chemical processes, such as chromium reduction in cement production. - Acts as a precursor for other iron compounds, including ferric sulfate and ferric oxide. 5. Dyeing and Pigments - Historically used as a mordant in textile dyeing to fix colors onto fabrics. - Contributes to the production of black and brown pigments. Safety and Environmental Impact While iron sulfate is generally considered low in toxicity, excessive ingestion can cause gastrointestinal distress. Proper handling is necessary to avoid skin and eye irritation. Environmentally, it is biodegradable but can contribute to water acidity if overused. Conclusion Iron sulfate is a versatile compound with applications spanning agriculture, medicine, industry, and environmental management. Its role in addressing iron deficiency, improving water quality, and supporting industrial processes makes it a valuable chemical in multiple sectors.