K2C2O4

Potassium oxalate is a chemical compound with the formula K2C2O4, a potassium salt of oxalic acid. In common laboratory use it is encountered as the dihydrate, K2C2O4·2H2O, though the anhydrous salt also exists. The solid consists of two potassium cations balanced by the oxalate dianion (C2O4^2−). In aqueous solution it dissociates into K+ and C2O4^2−, and oxalate can act as a bidentate ligand that forms complexes with various metal ions.

Preparation and forms: Potassium oxalate can be prepared by neutralizing oxalic acid with potassium hydroxide or potassium carbonate: H2C2O4 + 2 KOH → K2C2O4 + 2 H2O. The dihydrate form crystallizes readily from aqueous solutions, while dehydration yields the anhydrous salt, which is less common in routine use. The compound is typically handled in solid or aqueous form, with the dihydrate being the more familiar solid.

Properties: Potassium oxalate is a colorless, odorless solid that is soluble in water. It is stable at room temperature, but oxalate salts decompose upon strong heating, evolving gases and leaving oxide or carbonate residues.

Uses: In analytical chemistry it serves as a source of oxalate ions for precipitation and qualitative analysis, for example in the formation of calcium oxalate. It also finds use as a reagent in organic and inorganic synthesis and as a source of oxalate ligands in coordination chemistry.

Safety: Potassium oxalate is an oxalate compound and can be harmful if ingested; oxalates are associated with kidney stone risk. Handle with appropriate protective equipment, avoid contact with acids (which release oxalic acid), and follow standard waste disposal regulations for chemical reagents.