NaNO3

Sodium nitrate, chemical formula NaNO3, is an inorganic salt widely used as a source of nitrate. It is commonly known as sodium nitrate or Chile saltpeter. In pure form it appears as white, crystalline solid; it is highly soluble in water and hygroscopic. It behaves as an oxidizing agent and decomposes upon strong heating.

Occurrence and production

Sodium nitrate occurs in nature as the mineral nitratine (also called soda nitre) and is a major component of arid nitrate deposits collectively known as Chilean nitrate or Chile saltpeter. These deposits have historically been a major source of NaNO3, though production today also relies on synthetic routes. Industrially, sodium nitrate can be produced by neutralizing nitric acid with sodium carbonate: 2 HNO3 + Na2CO3 → 2 NaNO3 + CO2 + H2O. It has also been obtained as a byproduct of various nitric acid production processes.

Properties and reactions

Sodium nitrate is highly soluble in water and forms crystals that are typically monoclinic at room temperature. It is stable under ordinary conditions but readily decomposes upon heating to sodium nitrite and oxygen: 2 NaNO3 → 2 NaNO2 + O2. As an oxidizer, it can intensify combustion of organic materials and should be stored away from reducing agents and acids.

Uses

The principal use of sodium nitrate is as a fertilizer, supplying nitrate nitrogen to crops. It has historically served as a reservoir for nitrite in meat curing, and is employed in some curing blends. In pyrotechnics and early explosives, it has functioned as an oxidizer in formulations. It has also been used in glass and ceramic production as a heat-transfer aid and processing additive.

Safety and environmental considerations

Sodium nitrate is an oxidizer and can pose fire and health hazards if misused, especially in the presence of organic materials or reducing agents. Elevated nitrate levels in water can contribute to eutrophication and other environmental concerns; proper handling, storage, and disposal are important.