What are common examples of amphoteric oxides?

Common examples of amphoteric oxides include aluminium oxide (Al2O3), zinc oxide (ZnO), and lead(II) oxide (PbO).

Amphoteric oxides are oxides that can behave as both acids and bases. This means they can react with both acids and bases to form salts and water, a property that is unique to them. This dual behaviour is what gives them their name, with 'amphoteric' coming from the Greek word 'amphoteroi', meaning 'both'.

Aluminium oxide (Al2O3) is a classic example of an amphoteric oxide. When it reacts with an acid like hydrochloric acid (HCl), it behaves as a base and forms a salt (aluminium chloride) and water. Conversely, when it reacts with a base like sodium hydroxide (NaOH), it behaves as an acid and forms a different salt (sodium aluminate) and water.

Zinc oxide (ZnO) is another amphoteric oxide. It reacts with hydrochloric acid (HCl) to form zinc chloride and water, behaving as a base. But when it reacts with sodium hydroxide (NaOH), it forms sodium zincate and water, behaving as an acid.

Lead(II) oxide (PbO) also exhibits amphoteric properties. It reacts with hydrochloric acid (HCl) to form lead(II) chloride and water, acting as a base. However, when it reacts with sodium hydroxide (NaOH), it forms sodium plumbate and water, acting as an acid.

Understanding the concept of amphoteric oxides is crucial in chemistry as it helps to predict the behaviour of substances in different chemical reactions. It's also important to note that not all oxides are amphoteric; some are purely acidic or basic.