Barium Paramolybdate, 3BaO.7MoO₃.xH₂O

Barium Paramolybdate, 3BaO.7MoO₃.xH₂O or 5BaO.12MoO₃.yH₂O, is obtained by drying in air the flocculent precipitate resulting on addition of aqueous barium chloride to a solution of an alkali paramolybdate. If the precipitation takes place at ordinary atmospheric temperature, the composition of the product is represented by 5BaO.12MoO₃.20H₂O or 3BaO.7MoO₃.12H₂O; precipitation at boiling temperature yields 5BaO.12MoO₃.10H₂O. By allowing a solution containing barium chloride (1 molecule) and ammonium paramolybdate (10 molecules) to crystallise, the double salt 3(NH₄)₂O.3BaO.14MoO₃.12H₂O has been obtained.