Question

_______ reacts with acids and bases.
1. CuO
2. Al₂O₃
3. Na₂O
4. K₂O

Answer 1

Correct Answer - Option 2 : Al₂O₃

The correct answer is Al2O3.

•  Al2O3  reacts with acids and bases.
  • Aluminum oxide (Al2O3) is an amphoteric substance.
  • The amphoteric substance is a substance that can react with both acids and bases usually to produce salt and water.
  • Aluminium oxide therefore can react with both acids as well as bases. We will take the example of its reaction with hydrochloric acid (strong acid) and sodium hydroxide (strong base).
  • When mixed with these two compounds aluminium oxide either acts like  acid with a base and a base with an acid.

• Al₂O₃ + 6 HCl → 2 AlCl₃ + 3 H₂O (acts like a base)
• Al2O3 + 2 NaOH + 3 H₂O → 2 NaAl(OH)₄ (sodium aluminate) (acts like an acid)
• On reacting Al2O3 with HCl, we get Aluminium Chloride as the salt and water as a by-product.
  • Likewise, the reaction between NaOH ( Strong Base) and Al₂O₃ results in the formation of Sodium Aluminate as salt and water.