Cerium(III) sulfate, also called cerous sulfate, is an inorganic compound with the formula Ce2(SO4)3. It is one of the few salts whose solubility in water decreases with rising temperature. [1]
Cerium(III) sulfate (anhydrous) is a hygroscopic white solid, which begins to decompose above 600°C. It has a monoclinic crystal structure.
Cerium(III) sulfate tetrahydrate is a white solid that releases its water of crystallisation at 220 °C. It has (like the white octahydrate) a monoclinic crystal structure with the space group P21/c (space group 14). The nonahydrate has a hexagonal crystal structure with the space group P63/m (space group 176). Hydrates of this compound are known with 12, 9, 8, 5, 4 and 2 parts of water of crystallisation.