Rhodium Sulphite, Rh₂(SO₃)₃

Rhodium Sulphite, Rh₂(SO₃)₃.6H₂O, is obtained as a white crystalline mass on dissolving freshly precipitated rhodium sesquioxide in sulphurous acid. On concentration the crystals separate out, and are washed with alcohol, in which they are insoluble. Rhodium sulphite is fairly stable, but evolves sulphur dioxide on heating, leaving a residue of sesquioxide. With sulphites of the alkali metals, double salts are formed.