Question

“Aluminium oxide is an amphoteric oxide.” Justify this statement giving chemical equation for the reactions involved.

Answer 1

Because it can react with both acids and bases, acting as a base with acid and an acid with base to generate salt and water, aluminum oxide is an amphoteric oxide.

\[\ce{\underset{Base}{Al2O3} + \underset{Acid}{6HCl} -> \underset{chloride}{\underset{Aluminium}{2AlCl3}} + 3H2O}\]

\[\ce{\underset{Base}{Al2O3} + \underset{Acid}{2NaOH} -> \underset{Aluminate}{\underset{Sodium}{2NaAlO2}} + H2O}\]