Molybdic acid
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| Names | |
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| Other names
Molybdic(VI) acid
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| Identifiers | |
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3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.029.063 |
| EC Number | 231-970-5 |
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PubChem CID
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| Properties | |
| MoO3·H2O | |
| Molar mass | 161.95 g mol−1 |
| Density | 3.1 g cm−3 |
| Melting point | 300 °C (572 °F; 573 K) |
| 1510 mg dm−3 | |
| Hazards | |
| R-phrases (outdated) | R36/37/38 |
| S-phrases (outdated) | S24/25, S22 |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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| Infobox references | |
Molybdic acid refers to hydrated forms of molybdenum trioxide and related species. The monohydrate is MoO3·H2O and the dihydrate (MoO3·2H2O) are well characterized. They are yellow diamagnetic solids.
Solid forms of molybdic acid are coordination polymers. The monohydrate MoO3·H2O consists of layers of octahedrally coordinated MoO5·(H2O) units where 4 vertices are shared. The dihydrate (image shown above) has the same layer structure with the "extra" H2O molecule intercalated between the layers.
In acidified aqueous solutions of molybdic acid, the complex MoO3(H2O)3 is observed. Once again, molybdenum adopts octahedral molecular geometry, probably with three oxo ligands and three aquo ligands.
The salts of molybdic acid are called molybdates. They arise by adding base to solutions of molybdic acid.
Many molybdenum oxides are used as heterogeneous catalysts, e.g. for oxidations. Molybdic acid and its salts are used to make the Froehde reagent for the presumptive identification of alkaloids.
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