What are amphoteric oxides? Give two examples of amphoteric oxides?
OR
Write chemical equations that show aluminium oxide reacts with acid as well as base.

When a substance reacts chemically, both as a base or acid is termed as an amphoteric solution. As aluminium oxides, react with both acids and bases, it is known as Amphoteric Oxides.

The Chemical equations are given below:

$( i) \ Al_{2} O_{3} \ +\ 6HCl\ \rightarrow \ 2AlCl_{3} \ +\ 3H_{2} O.$

$( ii) \ Al_{2} O_{3} \ +\ 2NaOH\ \rightarrow \ 2NaAlO_{2} \ +\ H_{2} O.$

[Extra information: Amphoteric oxides are oxides of metals that have both acidic as well as basic behaviour. Such metallic oxides react with acids as well as a base to produce salt and water. It can accept or donate the proton or H⁺ ion, therefore, appearing as an acid or a base. 

 Examples of Amphoteric oxides are aluminum oxide(Al₂O₃) and zinc oxide(ZnO).

 

In base: $\ ZnO\ +\ 2\ NaOH\ +\ H_{2} O\rightarrow \ Na_{2}[ Zn( OH)_{4}]$

          Zinc Oxide + Sodium Hydroxide--> Sodium Zinc Hydroxide

In acid: $ZnO\ +\ H_{2} SO_{4}\rightarrow \ ZnSO_{4} +\ H_{2} O$

      Zinc Oxide + Sulphuric Acid --> Zinc Sulphate + Water]