Aluminum oxide, also commonly known as alumina, is typically white. It appears as a white solid under normal conditions.
Understanding Aluminum Oxide's Appearance and Properties
Aluminum oxide ($\text{Al}_2\text{O}_3$) is a chemical compound of aluminum and oxygen, recognized for its exceptional hardness and high melting point. Its characteristic white appearance is consistent across many of its forms, from fine powders used in industrial applications to its natural mineral forms like corundum.
Here's a quick overview of some key properties of aluminum oxide:
| Property | Value |
|---|---|
| Appearance | White solid |
| Molar mass | 101.960 g·mol−1 |
| Odor | Odorless |
| Density | 3.987 g/cm³ |
Common Forms and Uses
While pure aluminum oxide is white, its natural mineral forms can exhibit various colors due to impurities:
- Corundum: This is the crystalline form of aluminum oxide.
- Ruby: Red corundum, colored by chromium impurities.
- Sapphire: Corundum in nearly any color other than red (e.g., blue, yellow, pink), colored by trace elements like iron, titanium, or vanadium.
- Industrial Applications:
- As an abrasive in sandpaper and cutting tools due to its hardness.
- In the production of ceramics, refractories, and catalysts.
- As a crucial component in the production of aluminum metal.
- In biomedical applications due to its biocompatibility and wear resistance.
The widespread use of aluminum oxide in various industries often leverages its robust physical properties, including its typical white color, which can be an advantage in many products where color neutrality is desired.
