Synthesis of selenous acid

Preparation of selenous acid (selenious acid)

Preparation of selenous acid by oxidizing selenium with nitric acid

Like many non-metals, selenium is converted to selenous acid when dissolved in nitric acid. Selenous acid is a solid, soluble in water, whose solubility increases rapidly with the rise in temperature.

Preparation of selenous acid by oxidizing selenium with nitric acid

Preparation of selenous acid by oxidizing selenium with nitric acid

113 ml of concentrated nitric acid nitric are gently heated in the flask until the acid almost boils. A small amount of selenium is added and when this has been dissolved, the additional small amount of selenium is added. The addition is continued until all 39 grams of selenium have been added. The addition and heated during the addition is arranged so that the contents of the reaction in the flask will not boil over. After all the selenium has been added, the solution is boiled for 5 minutes in order to remove the red fumes of nitrogen dioxide. The flask is cooled, the solution is filtered, and the filtrate is left to stand in a previously weighed beaker until the solution has evaporated to dryness. The solution should not be evaporated to dryness as selenium dioxide (poison!) forms, which is volatilized by heat. The crude selenous acid is dissolved in one-fifth its weight of boiling water, cooled to room temperature, and the crystallization is initiated by seeding with small crystal or by rubbing the solution with a glass rod.  The solution is left to stand undisturbed in order to obtain large crystals, which are filtered, dried in a desiccator and stored in a stoppered bottle.

Synthetic inorganic chemistry, by A. A. Blanchard, 335-336, 1936


selenous acid



InChI Key


Canonical SMILES


MeSH Synonyms

Acid, Selenious, Acid, Selenous, Selenious Acid, Selenite, Selenous Acid

Depositor-Supplied Synonyms

SELENIOUS ACID, Selenous acid, 7783-00-8, Selenious acid (H2SeO3), (75se)selenous acid, Monohydrated selenium dioxide, UNII-F6A27P4Q4R, Selenium dioxide, monohydrated, CCRIS 5530, CHEBI:26642, HSDB 6065, EINECS 231-974-7, Selenious acid (USP), Selenious acid [USP], Seleniousacid, selenige Saeure, dihydroxidooxidoselenium, AC1L1APE, DSSTox_CID_4300, NCIMech_000026, DSSTox_RID_77360, DSSTox_GSID_24300, [SeO(OH)2], 211176_ALDRICH, 229857_ALDRICH, AC1Q59Y9, F6A27P4Q4R, CHEMBL2009089, 84920_FLUKA, CTK2H8628, MCAHWIHFGHIESP-UHFFFAOYSA-N, MolPort-003-927-836, KST-1A2960, Tox21_200407, AR-1A0197, CCG-35433, AKOS015960374, VZ36877, NCGC00248596-01, NCGC00257961-01, NCI60_003085, CAS-7783-00-8, LS-144800, TR-024855, SELENIOUS ACID, H2SeO3, D05814, 3B4-3809, I04-10294, selenious acid,selenous acid,monohydrated selenium dioxide, 11140-60-6, 1408288-83-4

Removed Synonyms

selenite, Hydrogen Selenite, SELENIUM DIOXIDE, RCRA waste no. U204, RCRA waste number U204, CID1091, 23428-84-4

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