Classifying Oxides
Section: Chemistry | Syllabus: Cambridge IGCSE Combined Science (0653)
Acidic and Basic Oxides
Oxides are classified according to their metallic or non-metallic character:
| Oxide type | Element type | Reacts with | Examples |
|---|---|---|---|
| Acidic oxide | non-metal | bases (forms salt + water) | SO₂, CO₂ |
| Basic oxide | metal | acids (forms salt + water) | CuO, CaO |
In general, moving from metals towards non-metals, oxide character changes from basic towards acidic.
Worked Example: Classifying Given Oxides
- Question: classify calcium oxide, carbon dioxide, manganese(IV) oxide, and sulfur dioxide as acidic or basic. [2]
- Answer: calcium oxide - basic (Ca is a metal); carbon dioxide - acidic (C is a non-metal); manganese(IV) oxide - basic (Mn is a metal); sulfur dioxide - acidic (S is a non-metal)
Common Mistakes
- ❌ Assuming all oxides are basic because most metal oxides are
- ✓ whether an oxide is acidic or basic depends on whether the other element is a non-metal (acidic, e.g. SO₂, CO₂) or a metal (basic, e.g. CuO, CaO)
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