Lanthanum(III) sulfate is an inorganic compound with the formula La2(SO4)3·"x"H2O (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.
Preparation and reactions.
The nonahydrate is produced by dissolving lanthanum or lanthanum hydroxide in dilute sulfuric acid, then evaporating the solution:
2 La + 3 H2SO4 → La2(SO4)3 + 3 H2
The anhydrous compound can be produced by heating the hydrates to 300 °C. If heated further, anhydrous lanthanum(III) sulfate decomposes to La2O2SO4 at 775 °C, which in turn decomposes to lanthanum(III) oxide at 1100 °C.
Structure.
The nonahydrate crystallizes in a hexagonal crystal system, which contains the lanthanum atoms in two different environments.