Selenous acid

Selenous acid (also known as selenious acid) is the chemical compound with the formula H2SeO3, perhaps more descriptively written as (HO)2SeO. Selenous acid is the principal oxoacid of selenium.

Formation and properties

Selenous acid is analogous to sulfurous acid, but it is more readily isolated. Selenous acid is easily formed upon the addition of selenium dioxide to water. As a crystalline solid, the compound can be seen as pyramidal molecules that are interconnected with hydrogen bonds. In solution it is a diprotic acid: [Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.] :H2SeO3 unicode| H+ + HSeO3- pKa = 2.62:HSeO3- unicode| H+ + SeO32- pKa = 8.32

It is moderately oxidizing in nature, but kinetically slow. In 1 M H+::H2SeO3 + 4H+ + 4e unicode| Se + 3H2O "E"o = +0.74 VIn 1 M OH::SeO32− + 4e + 3H2O unicode| Se + 6OH "E"o = −0.37 VIt is used in organic synthesis for the synthesis of 1,2-diketones (e.g. glyoxal). [ [ “Glyoxal Bisulfite”] , Organic Syntheses, Collected Volume 3, p.438 (1955).]

Health effects

Like many compounds of selenium, selenous acid is highly toxic, and ingestion of any significant quantity of selenous acid is usually fatal. Symptoms of selenium poisoning can occur several hours after exposure, and may include stupor, nausea, severe hypotension and death. [ [ MSDS for "Reagent for Special Opiates (Codeine, Heroin, & Morphine)"] , Sirchie Finger Print Laboratories, Inc. May 12, 2006.]


*S Sulfurous acid
*Se Selenous acid
*Te Tellurious acid
*Po Polonous acid


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Look at other dictionaries:

  • selenous acid — n. a colorless, transparent, crystalline powder, H2SeO3, soluble in water and used as a reagent: also selenious acid * * * …   Universalium

  • selenous acid — n. a colorless, transparent, crystalline powder, H2SeO3, soluble in water and used as a reagent: also selenious acid …   English World dictionary

  • selenous acid — selenito rūgštis statusas T sritis chemija formulė H₂SeO₃ atitikmenys: angl. selenous acid rus. селенистая кислота ryšiai: sinonimas – vandenilio trioksoselenatas (2–) …   Chemijos terminų aiškinamasis žodynas

  • selenous acid — noun the oxoacid HSeO; the selenium analogue of sulfurous acid See Also: selenic acid, selenite …   Wiktionary

  • selenous acid — /səlinəs ˈæsəd/ (say suhleenuhs asuhd) noun a weak, dibasic acid, H2SeO3 …   Australian English dictionary

  • selenous — variant of selenious * * * /seuh lee neuhs, sel euh /, adj. Chem. selenious. * * * selēˈnious or selēˈnous adjective Of selenium in lower valency (selenious acid H2SeO3) • • • Main Entry: ↑selenic …   Useful english dictionary

  • Selenium dioxide — Selenium dioxide …   Wikipedia

  • Selenium — (pronEng|səˈliniəm) is a chemical element with the atomic number 34, represented by the chemical symbol Se, an atomic mass of 78.96. It is a nonmetal, chemically related to sulfur and tellurium, and rarely occurs in its elemental state in nature …   Wikipedia

  • Petr Zuman — (born January 1926) is a Czech chemist. Born and raised in Prague, the Second World War severely impacted Zuman and his family while he was a teenager. In 1939, when he was 13 years old, the Germans occupied Czechoslovakia and sent his father to… …   Wikipedia

  • selenite — noun a) A soft, glassy form of gypsum (chemical formula CaSO·2HO). b) The anion SeO derived from selenous acid; any salt or ester of selenous acid. Syn …   Wiktionary

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