Simple molybdates of aluminium (Aluminium Molybdates) have not been prepared, but by dissolving aluminium hydroxide in solutions of alkali tri- or para-molybdates, and allowing to crystallise, salts of the type 3R•2O.Al2O3.12MoO3.aq. are obtained. These may be represented as derivatives of the alkali aluminates thus: R•3Al(Mo2O7)3.aq. The following have been described:
3(NH4)2O.Al2O3. 12MoO3.19H2O (or 20 or 22H2O), white, lustrous, quadratic crystals.
3K2O.Al2O3.12MoO3.20H2O, flat white plates or cubes, stable in air.
3Na2O.Al2O3.12MoO3.22H2O, efflorescent needles.
The barium salt, 4BaO.Al2O3.12MoO3.14H2O, is precipitated when a soluble barium salt is added to a solution of the potassium compound. The complex, Al2O3.12MoO3, is very stable, and similar compounds with analogous complexes, containing the sesquioxides of chromium, cobalt, iron, manganese, and nickel, have also been prepared. |