Samarium sulphate, Sm₂(SO₄)₃

The systems Sm2(SO4)3 - Na2SO4 - H2O and Sm2(SO4)3 - (NH4)2SO4 - H2O at 25°. Solubility diagrams.

The monoclinic Samarium sulphate octahydrate, Sm₂(SO₄)₃.8H₂O, is the only hydrate known. The acid sulphate, Sm(HSO₄)₃, and the basic sulphate, Sm₂O₃.SO₃, are known. The following double sulphates have been described by Cleve: - 2Sm₂(SO₄)₃.9K₂SO₄.3H₂O; Sm₂(SO₄)₃.(NH₄)₂SO₄.8H₂O; Sm₂(SO₄)₃.Na₂SO₄.2H₂O.

According to Keyes and James, the only double sodium and ammonium sulphates that exist at 25° have the formulae 2Sm₂(SO₄)₃.3Na₂SO₄.6H₂O and Sm₂(SO₄)₃.(NH₄)₂SO₄.7H₂O. The results of their solubility measurements are shown graphically in fig.