Samples of ruby, a red variant of corundum.
| IUPAC name
| Systematic IUPAC name
| Other names
|Molar mass||101.96 g/mol|
|Melting point||2,072 °C (3,762 °F; 2,345 K)|
|Boiling point||2,977 °C (5,391 °F; 3,250 K)|
|Solubility|| Reacts with halogenic acids and alkali|
Insoluble in organic solvents
|Vapor pressure||~0 mmHg|
Std enthalpy of
|Safety data sheet||Sigma-Aldrich|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Aluminium oxide or alumina is the chemical compound of aluminum and oxygen, with chemical formula Al2O3. It's the most common and stable form of the aluminium oxides. Aluminium oxide occurs naturally in it's crystalline alpha phase as mineral corundum.
Aluminium oxide will react with sodium hydroxide to form sodium aluminate.
Aluminium oxide is a white solid compound, insoluble in water and solvent, but will dissolve in non-oxidizing acids. It is odorless and it's very hard (9 Mohs scale). It's an electrical insulator.
Aluminium oxide is often present in sandpapers, you can also buy it from mineral collectors as corrundum or gemstones like ruby or sapphire.
Heating elements also contain alumina powder which acts as an insulator for the resistance wiring.
Aluminium oxide is a product of thermite reaction:
- M2O3 + 2 Al → Al2O3 + 2 M
This reaction also gives various aluminates, and separating the alumina from the slag is complicated and may not worth it.
A much better method involves the dehydration of aluminium hydroxide
- Make aluminium salts
No special handling is necessary, though it's recommonded to avoid inhaling in in powdered form. Aluminium oxide isn't flamable or explosive.
Storage in closed bottles is adequate.
Aluminium oxide could be safely dumped with normal trash or spilled out in a soil.