Ferrous oxalate, or iron (II) oxalate, is a derivative of Oxalic Acid. It is an inorganic compound whose chemical formula is FeC₂O₄.  It is an odorless yellow solid whose molar mass is 143.86 g/mol. It is poorly soluble in water and is soluble in acids. It is used in the metal treatment industry, photo developers’ formulations, and the textile industry. Ferrous oxalate is most commonly encountered in its dihydrate form, i.e., FeC₂O₄·2H₂O. Ferrous oxalate is used for decorative glassware, as a pigment for plastics, paints, and lacquers, in the metal treatment industry, in photo developers’ formulations, and the textile industry.

Properties of Ferrous Oxalate

Chemical Formula : FeC₂O₄ (anhydrous) ; FeC₂O₄ · 2H₂O (dihydrate)

Molar mass : 143.86 g/mol (anhydrous) ; 179.89 g/mol (dihydrate)

Density : 2.28 g/cm³

Appearance : yellow powder

Odour : odorless

Melting point : 190 °C (anhydrous) ; 150–160 °C (dihydrate)

Boiling point : 365.1 °C (anhydrous)

Solubility : Poorly soluble in water and soluble in acids 

Uses of Ferrous Oxalate

1. Ferrous oxalate is used as a photographic developer for silver bromide-gelatin plates.

2. It is used to impart a greenish-brown tint to optical glass (like sunglasses, windshields, and railroad car windows).

3. It is used in the metal treatment industry and the textile industry.

4. It is also used as a glass tint (sunglasses and windshields) and as a pigment for plastics, paints, and lacquers.