Reaction of aluminium:

(a) Air: Aluminium forms oxide at room temperature.

Aluminium powder burns in air at about 800°C forming its oxide and nitride with a bright light.

4Al + 3O₂ → 2Al₂O₃

2Al + N₂ → 2AlN

(b) Water: Water has no action on aluminium due to layer of oxide on it.

When steam is passed over pure heated aluminium, hydrogen is produced.

2Al +3H₂O ⟶ Al₂O₃ +3H₂

(c) Acid: It reacts with acids to produce salt and hydrogen.

2Al + 6HCl → 2 AlCl₃ +3H₂

Dilute sulphuric acid reacts with metal to liberate hydrogen.

2Al + 3H₂SO₄ (dilute) → Al₂(SO₄)₃ +3H₂

Concentrated sulphuric acid reacts with aluminium to produce sulphur dioxide.

2Al + 6H₂SO₄ → Al₂(SO₄)₃ +6H₂O +3SO₂

Dilute and concentrated nitric acid does not attack the metal aluminium.

(d) Base: Aluminium reacts with boiling and dilute alkalies to produce meta aluminate while with fused alkali produce aluminate.

2Al+ 2NaOH +2H₂O → 2NaAlO₂ +3H₂

(Sodium meta aluminate)

2Al + 6NaOH → 2Na₃AlO₃ + 3H₂

(Sodium aluminate)