What are amphoteric oxides?

Amphoteric oxides are oxides of metals that can react with both acids and bases to form salts and water. They show both acidic and basic properties.

Acidic behavior: When reacting with a base, an amphoteric oxide acts as an acid, accepting hydroxide ions (OH⁻).

Basic behavior: When reacting with an acid, an amphoteric oxide acts as a base, accepting protons (H⁺).

Examples:

Two common examples of amphoteric oxides are:

1. Aluminum oxide (Al₂O₃):

   • Reaction with an acid (e.g., hydrochloric acid): Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O
   • Reaction with a base (e.g., sodium hydroxide): Al₂O₃ + 2NaOH + 3H₂O → 2Na[Al(OH)₄] (sodium tetrahydroxoaluminate)

2. Zinc oxide (ZnO):

   • Reaction with an acid (e.g., sulfuric acid): ZnO + H₂SO₄ → ZnSO₄ + H₂O
   • Reaction with a base (e.g., potassium hydroxide): ZnO + 2KOH → K₂[Zn(OH)₄] (potassium tetrahydroxozincate)