Potassium Nitrate (KNO₃) 7757-79-1

Potassium Nitrate (KNO₃), also known as saltpeter, is a white crystalline ionic salt with a molecular weight of 101.10 g/mol. It is highly soluble in water, contains 44% K₂O and 13% nitrogen, and is produced by reacting potassium chloride with nitric acid or from natural deposits. It is used in fertilizers, food preservation, glass manufacturing, and pyrotechnics.

Potassium nitrate is a premium, chloride-free fertilizer supplying both potassium and nitrogen in forms readily available to plants. It is particularly valuable for chloride-sensitive, high-value crops such as tobacco, potatoes, citrus, grapes, strawberries, tomatoes, and greenhouse vegetables. It can be applied through fertigation systems, as a foliar spray, or as a dry soil application. Its high solubility makes it ideal for precision agriculture and hydroponic nutrient solutions.

Food-grade potassium nitrate (E252) is used as a preservative in cured and processed meats such as bacon, ham, salami, and corned beef. It inhibits the growth of Clostridium botulinum and helps maintain the characteristic pink color of cured meats by forming nitrosomyoglobin. It is typically used in combination with sodium chloride in curing salt formulations at strictly controlled concentrations.

In glass manufacturing, potassium nitrate is used as a chemical strengthening agent. When glass is immersed in molten potassium nitrate at approximately 400°C, potassium ions from the salt exchange with smaller sodium ions in the glass surface. This ion exchange creates a compressive stress layer on the glass surface, significantly increasing its strength and scratch resistance. This process is used to produce chemically strengthened glass for smartphone screens, aircraft windows, and other demanding applications.

Potassium nitrate is a strong oxidizer that supports combustion. It should be stored away from heat sources, sparks, open flames, and reducing agents such as organic materials, sulfur, and metal powders. It is not combustible itself but can intensify fires when involved. Store in a cool, dry, well-ventilated area in tightly sealed containers. Avoid contamination with incompatible materials. Under proper storage conditions, potassium nitrate has excellent long-term stability.