Selenous acid (also known as selenious acid) is the
chemical compoundwith the formula H2SeO3, perhaps more descriptively written as (HO)2SeO. Selenous acid is the principal oxoacidof 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 dioxideto 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 synthesisfor the synthesis of 1,2-di ketones (e.g. glyoxal). [ [http://www.orgsyn.org/orgsyn/pdfs/CV3P0438.pdf “Glyoxal Bisulfite”] , Organic Syntheses, Collected Volume 3, p.438 (1955).]
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. [ [http://www.sirchie.com/msds/NARK20010.pdf MSDS for "Reagent for Special Opiates (Codeine, Heroin, & Morphine)"] , Sirchie Finger Print Laboratories, Inc. May 12, 2006.]
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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