Ammonium heptamolybdate tetrahydrate

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.

Uses

• as an analytical reagent to measure the amount of phosphates, silicates, arsenates and lead in aqueous solution (e.g. pigments, river water, sea water etc.)
• in the production of molybdenum metal and ceramics
• in the preparation of dehydrogenation and desulfurization catalysts
• in the fixing of metals
• in electroplating
• in fertilizers for crops.
• as a negative stain in biological electron microscopy, typically in the 3–5% (vol/vol) concentration range and in the presence of trehalose; or at saturated concentration to perform cryo-negative staining.
• For the detection of recreational drugs as a component of the Froehde reagent