Lanthanum(III) sulfate is an inorganic compound with the formula La<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>÷xH<sub>2</sub>O (0 ⤠x ⤠9). It forms various hydrates, the most common one being the nonahydrate, which are all white solids. It is an intermediate in producing lanthanum from its ores.
The nonahydrate is produced by dissolving lanthanum or lanthanum hydroxide in dilute sulfuric acid, then evaporating the solution:
The anhydrous compound can be produced by heating the hydrates to 300 ðC. If heated further, anhydrous lanthanum(III) sulfate decomposes to La<sub>2</sub>O<sub>2</sub>SO<sub>4</sub> at 775 ðC, which in turn decomposes to lanthanum(III) oxide at 1100 ðC.
The nonahydrate crystallizes in a hexagonal crystal system, which contains the lanthanum atoms in two different environments.