Sodium selenite (English name: Sodium selenite) is an inorganic compound with the chemical formula Na2SeO3 and a molecular weight of approximately 172.94.
Colorless and odorless crystals, usually appearing white due to the presence of crystalline water. It is stable in ordinary air but prone to surface weathering and water loss in dry air. It is insoluble in alcohol but highly soluble in water. At 20℃, it contains approximately 68 grams of pentahydrate (Na2SeO3·5H2O) in 100 grams of solution.
Sodium selenite is a medium-strong oxidizing agent in acidic solutions and is easily reduced by organic acids in the presence of oxidizing agents.
Sodium selenite is usually produced by the reaction of selenite with sodium hydroxide. Industrially, elemental selenium can be dissolved in nitric acid to obtain selenite, or gaseous selenium can be reacted with oxygen to form selenium dioxide and then dissolved in water to obtain selenite, which is then neutralized with sodium hydroxide solution. Sodium selenite can be used as an alkaloid reagent, bacteriological reagent, nutrient fortifier, feed additive, and glass de-greenening agent, and is applied in fields such as glaze, glass, medicine, feed, and biology.
Although sodium selenite is often used to treat diseases caused by selenium deficiency, such as cancer, cardiovascular diseases, Keshan disease and postoperative selenium response syndrome, it is highly toxic and requires very little. Excessive intake can lead to poisoning and death. Acute toxic reactions include neurological symptoms, spasms, shortness of breath, vomiting, drowsiness, etc. Chronic poisoning is manifested as gastrointestinal dysfunction, fatigue, ascites, anemia, dizziness, nail deformity and liver and kidney damage. Frequent inhalation of low-concentration dust can cause symptoms such as fatigue, loss of appetite, indigestion and bronchitis. Sodium selenite is also corrosive. Its solution can cause burns when it comes into contact with the skin and cause severe pain when absorbed through the skin of the fingertips. Long-term contact may also lead to dermatitis.
