Oxalic acid

Oxalic acid is an <a href="/facts/Organic_acid/2Pfb26Lp">organic acid</a> with the systematic name ethanedioic acid and <a href="/facts/Chemical_formula/hghUtthl">chemical formula</a> HO−C(=O)−C(=O)−OH, also written as (COOH)2 or (CO2H)2 or H2C2O4. It is the simplest <a href="/facts/Dicarboxylic_acid/d69GkIAc">dicarboxylic acid</a>. It is a white crystalline solid that forms a colorless solution in water. Its name is derived from early investigators who isolated oxalic acid from <a href="/facts/Flowering_plant/E5eGYIvY">flowering plants</a> of the genus <a href="/facts/Oxalis/0HU68UMr">Oxalis</a>, commonly known as wood-sorrels. It occurs naturally in many foods. Excessive ingestion of oxalic acid or prolonged skin contact can be dangerous.
Oxalic acid is a much stronger acid than <a href="/facts/Acetic_acid/uyBKA2Pd">acetic acid</a>. It is a <a href="/facts/Reducing_agent/CtfSGVXC">reducing agent</a> and its <a href="/facts/Conjugate_base/hohgQ07M">conjugate bases</a> <a href="/facts/Hydrogen_oxalate/GNG4pAxP">hydrogen oxalate</a> (HC2O−4) and <a href="/facts/Oxalate/u0Gdem0A">oxalate</a> (C2O2−4) are <a href="/facts/Chelating_agents/4G79sXBB">chelating agents</a> for metal cations. It is used as a cleaning agent, especially for the removal of <a href="/facts/Rust/sajUmaz8">rust</a>, because it forms a water-soluble ferric iron complex, the <a href="/facts/Ferrioxalate/sLg3Y0yn">ferrioxalate</a> ion. Oxalic acid typically occurs as the <a href="/facts/Water_of_crystallization/sbaKJNJX">dihydrate</a> with the formula H2C2O4·2H2O.

Oxalic acid open-in-new

Oxalic acid