Selenious acid is the acid form of sodium selenite, a form of selenium. Selenium is an essential trace element and antioxidant. It is a cofactor metabolic enzyme regulation. ... Selenous acid is a selenium oxoacid.

Selenious Acid is a white, crystalline (sand-like) solid. It is used as a component for gun blueing, a reagent, an oxidizing agent, and an isotope for labeling radiopharmaceutical compounds.

Uses. The major use is in protecting and changing the color of steel, especially steel parts on firearms. The so-called cold-bluing process uses selenous acid, copper(II) nitrate, and nitric acid to change the color of the steel from silver-grey to blue-grey or black.

Selenium dioxide is very soluble in water, and selenous acid, H2SeO3, can be isolated from the aqueous solutions. ... Both selenic and telluric acids are diprotic acids, with the former being much stronger than the latter (Kat: H2SeO4 1; H6TeO6 ~ 10−7). Both acids are much stronger oxidizing agents than sulfuric acid.

SELENOUS ACID