Question

# Write reactions to justify the amphoteric nature of aluminum.

Hint: Amphoteric compounds are the compounds which can react with both acids as well as bases. Along with aluminum, copper, zinc, tin, lead is also amphoteric in nature. These metals usually form amphoteric oxides or hydroxides.

We know that species which react with both acids as well bases are amphoteric in nature. To prove the amphoteric nature of aluminium we have to show the reaction of aluminium with acid and base. Reaction of aluminium with an acid is as follows:
$2Al\left( s \right) + 3{H_2}S{O_4}\left( {aq} \right)\xrightarrow{{}}A{l_2}{\left( {S{O_4}} \right)_3}\left( {aq} \right) + 3{H_2}\left( g \right)$
This is how aluminium reacts with an acid. Metals react with acids to liberate hydrogen gas.
Reaction of aluminium with base:
$2Al\left( s \right) + 2NaOH\left( {aq} \right) + 6{H_2}O\left( l \right)\xrightarrow{{}}2N{a^ + }{\left[ {Al\left( {O{H_4}} \right)} \right]^ - }\left( {aq} \right) + 3{H_2}\left( g \right)$
This is how aluminium reacts with base.