Molybdenum trioxide
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| Names | |||
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| IUPAC name
Molybdenum trioxide | |||
| Other names | |||
| Identifiers | |||
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3D model (JSmol) |
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| ChEBI | |||
| ChemSpider | |||
| ECHA InfoCard | 100.013.823 | ||
| EC Number |
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PubChem CID |
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| UNII | |||
| UN number | 3288 | ||
CompTox Dashboard (EPA) |
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| Properties | |||
| MoO3 | |||
| Molar mass | 143.95 g·mol−1 | ||
| Appearance | yellow solid | ||
| Odor | odorless | ||
| Density | 4.70 g/cm3 | ||
| Melting point | 802 °C (1,476 °F; 1,075 K) | ||
| Boiling point | 1,155 °C (2,111 °F; 1,428 K)(sublimes) | ||
| 1.066 g/L (18 °C) 4.90 g/L (28 °C) 20.55 g/L (70 °C) | |||
| Band gap | >3 eV (direct) | ||
| +3.0·10−6 cm3/mol | |||
| Structure | |||
| Orthorhombic, oP16 | |||
| Pnma, No. 62 | |||
a = 1.402 nm, b = 0.37028 nm, c = 0.39663 nm | |||
Formula units (Z) |
4 | ||
| see text | |||
| Thermochemistry | |||
Heat capacity (C) |
75.0 J K−1 mol−1 | ||
Std molar entropy (S⦵298) |
77.7 J K−1 mol−1 | ||
Std enthalpy of formation (ΔfH⦵298) |
−745.1 kJ/mol | ||
Gibbs free energy (ΔfG⦵) |
−668.0 kJ/mol | ||
| Hazards | |||
| GHS labelling: | |||
| Warning | |||
| H319, H335, H351 | |||
| P201, P202, P261, P264, P271, P280, P281, P304+P340, P305+P351+P338, P308+P313, P312, P337+P313, P403+P233, P405, P501 | |||
| NFPA 704 (fire diamond) | |||
| Flash point | Non-flammable | ||
| Lethal dose or concentration (LD, LC): | |||
LD50 (median dose) |
125 mg.kg (rat, oral) 2689 mg/kg (rat, oral) | ||
LDLo (lowest published) |
120 mg Mo/kg (rat, oral) 120 mg Mo/kg (guinea pig, oral) | ||
LC50 (median concentration) |
>5840 mg/m3 (rat, 4 hr) | ||
| Related compounds | |||
Other cations |
Chromium trioxide Tungsten trioxide | ||
Related molybdenum oxides |
Molybdenum dioxide "Molybdenum blue" | ||
Related compounds |
Molybdic acid Sodium molybdate | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references | |||
Molybdenum trioxide describes a family of inorganic compounds with the formula MoO3(H2O)n where n = 0, 1, 2. The anhydrous compound is produced on the largest scale of any molybdenum compound since it is the main intermediate produced when molybdenum ores are purified. The anhydrous oxide is a precursor to molybdenum metal, an important alloying agent. It is also an important industrial catalyst. It is a yellow solid, although impure samples can appear blue or green.