Na2SeO3

Na2SeO3, commonly called sodium selenite, is an inorganic compound that is the sodium salt of selenious acid (H2SeO3). It appears as a white to colorless crystalline solid and is highly soluble in water. In aqueous solution it forms the selenite ion, SeO3^2-, and solutions are often mildly basic. It undergoes redox chemistry: it can be oxidized to sodium selenate (Na2SeO4) and can be reduced to elemental selenium or other selenium species under appropriate conditions.

Preparation and occurrence: Sodium selenite is typically prepared by neutralizing selenous acid with sodium hydroxide. It is used industrially as a source of selenium and in various laboratory procedures.

Uses: In agriculture and animal nutrition it serves as a dietary selenium supplement, supplied in trace amounts to livestock and poultry. In chemistry it provides a soluble selenium source for synthesis and analysis, and is used in qualitative and quantitative procedures involving selenium chemistry.

Safety and handling: Sodium selenite is toxic and should be handled with appropriate precautions. Ingestion, inhalation, or dermal exposure can be harmful. It should be stored away from oxidizing agents and acids, and waste should be disposed of as hazardous selenium-containing material.