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 chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solub ...

in water decreases with rising temperature. Cerium (III) sulfate ( anhydrous) is a

hygroscopic Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substan ...

white solid, which begins to decompose above 600°C. It has a

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic s ...

crystal structure In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions or molecules in a crystalline material. Ordered structures occur from the intrinsic nature of the constituent particles to form symmetric patterns ...

. 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 ''P''2₁/''c'' (

space group In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it uncha ...

14). The nonahydrate has a hexagonal crystal structure with the space group ''P''6₃/''m'' (space group 176). Hydrates of this compound are known with 12, 9, 8, 5, 4 and 2 parts of water of crystallisation.

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