Question

Write one reaction in which aluminium oxide behaves as a basic oxide and another in which it behaves as an acidic oxide.

Answer 1

1. Aluminium oxide reacts with hydrochloric acid to form aluminium chloride (salt) and water.

\[\ce{\underset{Aluminium oxide}{Al2O3_{(s)}} + \underset{(Acid)}{\underset{Hydrochloric acid}{6HCl_{(aq)}}} -> \underset{(Salt)}{\underset{Aluminium chloride}{2AlCl3_{(aq)}}} + \underset{Water}{3H2O_{(l)}}}\]

In this reaction, aluminium oxide behaves as a basic oxide (because it reacts with an acid to form a salt and water).

2. Aluminium oxide reacts with sodium hydroxide to form sodium aluminate (salt) and water.

\[\ce{\underset{Aluminium oxide}{Al2O3_{(s)}} + \underset{(Base)}{\underset{Sodium hydroxide}{2NaOH_{(aq)}}} -> \underset{(Salt)}{\underset{Sodium aluminate}{2NaAlO2_{(aq)}}} + \underset{Water}{H2O_{(l)}}}\]

In this reaction, aluminium oxide behaves as an acidic oxide (because it reacts with a base to form a salt and water).