Description

Ferrous sulfate refers to a group of chemical compounds with the formula FeSO₄·xH₂O, where ‘x’ represents the number of water molecules of hydration. The most common form is the heptahydrate (FeSO₄·7H₂O), which appears as pale green or bluish-green crystals. Other hydrates, such as the monohydrate (FeSO₄·H₂O), also exist.

It is readily soluble in water, forming acidic solutions due to the hydrolysis of the Fe²⁺ ion. Upon exposure to air and moisture, especially in solution, ferrous sulfate slowly oxidizes to ferric sulfate (Fe₂(SO₄)₃), resulting in a brownish-yellow color.

Key applications of ferrous sulfate include:

• Iron supplement: It is a widely used treatment for iron deficiency anemia in humans and animals, providing a bioavailable form of iron.  
• Water treatment: Ferrous sulfate is employed as a flocculant in water and wastewater treatment to remove suspended solids and phosphates. It reacts with alkalinity in the water to form ferric hydroxide, a gelatinous precipitate that traps impurities.  
• Mordant in dyeing: In the textile industry, it acts as a mordant, helping dyes to bind permanently to fabrics.  
• Soil amendment: In agriculture, it can be used to treat iron chlorosis (iron deficiency) in plants and to lower the pH of alkaline soils.  
• Production of other iron compounds: It serves as a precursor in the synthesis of other iron-containing chemicals, such as ferric oxide pigments.  
• Reducing agent: In some chemical processes, ferrous sulfate acts as a reducing agent.

Handling ferrous sulfate requires care as it can be irritating to the skin and eyes. Ingestion of large amounts can be toxic.