Ammonium ferrous sulfate, commonly known as Mohr's salt, is a pale green, crystalline inorganic compound. Its chemical formula is (NH₄)₂Fe(SO₄)₂·6H₂O. It is also known as ammonium iron(II) sulfate or ferrous ammonium sulfate. Mohr's salt is a double salt of ferrous sulfate and ammonium sulfate, meaning it contains two different cations, Fe²⁺ and NH₄⁺. Uses Mohr's salt has various applications, including: Analytical Chemistry: It is used as a reductometric standard in titrations involving oxidizers such as ceric, dichromate, and permanganate ions. Medicine: It is used in the production of iron supplements and has been historically used to treat infections and gastric symptoms. Water Treatment: It can be used as a coagulant to remove suspended particles in wastewater. It also reduces water acidity, making it safer for consumption. Metallurgy: It is used in iron plating baths and brass coloring baths. Agriculture: It is used in fertilizers and pesticide sprays to correct iron deficiencies in plants. Fire Safety: It is used as a flame retardant for textiles and plastics. Photography: It reacts with silver salts to develop photographic films and papers. Other Applications: It has been used in wastewater treatment, tanning, production of dyestuffs, as an etching agent in the production of electronic components, in adiabatic refrigeration equipment, biochemical analysis, and organic synthesis. Toxicity and Safety Mohr's salt is considered a hazardous substance. Inhalation of the dust can irritate the nose and throat, causing coughing and wheezing. Ingestion can irritate the mouth and stomach, potentially leading to nausea, vomiting, diarrhea, and black stool. Eye and skin contact can cause irritation. Prolonged exposure to the substance may cause damage to the liver and spleen. It is essential to handle Mohr's salt with care, wear appropriate protective equipment (gloves, safety glasses, lab coat, dust respirator), and work in a well-ventilated area to minimize exposure. In case of spills, it is important to evacuate the area, collect the material, and dispose of it properly according to local regulations.