Question

What are amphoteric oxides?

Hint:

Remember 'Al' and 'Zn' as the "dual-nature" metals whose oxides (\( Al_2O_3 \) and \( ZnO \)) are the most common examples of amphoteric oxides in exams.

Answer 1

What are Amphoteric Oxides?

Amphoteric oxides are those oxides which react with both acids and bases to form salt and water. In other words, they show both acidic as well as basic properties.

The term “amphoteric” means having a dual nature. Therefore, amphoteric oxides behave like acids when they react with bases and behave like bases when they react with acids.

Examples of Amphoteric Oxides:
– Aluminium oxide (Al₂O₃)
– Zinc oxide (ZnO)
– Lead oxide (PbO)

Reactions Showing Amphoteric Nature:
1. Reaction with Acid (acts as base):
\[ Al_2O_3 + 6HCl \rightarrow 2AlCl_3 + 3H_2O \] Here aluminium oxide reacts with hydrochloric acid to form aluminium chloride and water.

2. Reaction with Base (acts as acid):
\[ Al_2O_3 + 2NaOH \rightarrow 2NaAlO_2 + H_2O \] Here aluminium oxide reacts with sodium hydroxide to form sodium aluminate and water.

Conclusion:
Amphoteric oxides are oxides that react with both acids and bases. They exhibit both acidic and basic properties. Common examples include aluminium oxide and zinc oxide.