Molybdic acid monohydrate

The solubility curve of the dihydrate cuts that of the monohydrate at 32° C. On heating, two distinct varieties of molybdic acid monohydrate are fonned on concentrating the solution of the dihydrate at 40° to 50° C., a-molyhdic acid monoJuidrate is formed as asbestos-like white needles, retaining their water of crystallisation much more readily than p-molybdic acid monohydrate, which is obtained as small white needles, soluble in water, but not regenerating the dihydrate, by heating the dihydrate to 70° C. White a-molybdic acid is readily obtained by treating methyl molybdate with water. The solubility in water of the monohydrate is as follows ... 

The monohydrate is prepared by treating a molybdate solution with nitric acid, followed by crystallization which may take several weeks to separate out as a yellow solid. The anhydrous molybdic acid is obtained as a white crystalline substance by careful dehydration of the yellow monohydrate. 

Manganese Molybdate, MnMoO, is obtained in the anhydrous condition by fusing together sodium molybdate, manganous chloride, and sodium chloride. By treating normal or acid molybdate solutions vith manganous salts, the manganese molybdate may be separated in the hydrated condition. Several hydrates have been described, but the existence of the monohydrate only appears to be established. This is a white crj stalline powder. 

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