Boron trioxide
Boron trioxide or diboron trioxide is the oxide of boron with the formula B2O3. It is a colorless transparent solid, almost always glassy (amorphous), which can be crystallized only with great difficulty. It is also called boric oxide or boria. It has many important industrial applications, chiefly in ceramics as a flux for glazes and enamels and in the production of glasses.
| Names | |
|---|---|
| IUPAC name
Diboron trioxide | |
| Other names
boron oxide, diboron trioxide, boron sesquioxide, boric oxide, boria Boric anhydride | |
| Identifiers | |
3D model (JSmol) |
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| ChEBI | |
| ChemSpider | |
| ECHA InfoCard | 100.013.751 |
| EC Number |
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| 11108 | |
PubChem CID |
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| RTECS number |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties | |
| B2O3 | |
| Molar mass | 69.6182 g/mol |
| Appearance | white, glassy solid |
| Density | 2.460 g/cm3, liquid; 2.55 g/cm3, trigonal; |
| Melting point | 450 °C (842 °F; 723 K) (trigonal) 510 °C (tetrahedral) |
| Boiling point | 1,860 °C (3,380 °F; 2,130 K) , sublimes at 1500 °C |
| 1.1 g/100mL (10 °C) 3.3 g/100mL (20 °C) 15.7 g/100mL (100 °C) | |
| Solubility | partially soluble in methanol |
| Acidity (pKa) | ~ 4 |
| −39.0·10−6 cm3/mol | |
| Thermochemistry | |
Heat capacity (C) |
66.9 J/(mol⋅K) |
Std molar entropy (S⦵298) |
80.8 J/(mol⋅K) |
Std enthalpy of formation (ΔfH⦵298) |
−1254 kJ/mol |
Gibbs free energy (ΔfG⦵) |
−832 kJ/mol |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards |
Irritant |
| GHS labelling: | |
| Danger | |
| H360FD | |
| P201, P202, P281, P308+P313, P405, P501 | |
| NFPA 704 (fire diamond) | |
| Flash point | noncombustible |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose) |
3163 mg/kg (oral, mouse) |
| NIOSH (US health exposure limits): | |
PEL (Permissible) |
TWA 15 mg/m3 |
REL (Recommended) |
TWA 10 mg/m3 |
IDLH (Immediate danger) |
2000 mg/m3 |
| Supplementary data page | |
| Boron trioxide (data page) | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references | |
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