Characteristic

Ammonium heptamolybdate is the inorganic compound whose chemical formula is (NH4)6Mo7O24, normally encountered as the tetrahydrate. A dihydrate is also known. It is a colorless solid, often referred to as ammonium paramolybdate or simply as ammonium molybdate, although "ammonium molybdate" can also refer to ammonium orthomolybdate, (NH₄)₂MoO₄, and several other compounds. It is one of the more common molybdenum compounds.

Chemical formula:(NH₄)₆Mo₇O₂₄•xH₂O

Molar mass: 1163.9 g/mol;1235.86 g/mol (tetrahydrate)

Appearance:white solid

Density:2.498 g/cm³

Melting point:~90 ˚C (loses water molecule);190 °C (decomp.)

Solubility in water:65.3 g / 100 ml (tetrahydrate)

Application

It is used for ceramics, decorating, electroplating, fixing of metals, fertilizers, photography, and as a negative stain in electron microscopy. It is also used in the manufacture of molybdenum. It is a useful reagent for detecting and determining phosphates, arsenates, lead and some alkaloids. It is useful in the preparation of catalysts for desulfurization and dehydrogenation reactions. Ammonium molybdate has been reported to control polycondensation reactions and decrease shrinkage values of metakaolin-based geopolymers.