Al is amphoteric. Why? Also show that it is amphoteric with suitable example reactions.
It reacts with acids to form Al3+ ions:
Al2O3 + 6 H+ --> 2 Al3+ + 3 H2O
It reacts with bases to form Al(OH)4- ion (that's 4 hydroxides and a 1- charge):
Al2O3 + 2 OH- + 3 H2O --> 2 Al(OH)4- .
Reaction with both acids and bases is what defines amphoteric.
Al2O3 + 6 H+ --> 2 Al3+ + 3 H2O
It reacts with bases to form Al(OH)4- ion (that's 4 hydroxides and a 1- charge):
Al2O3 + 2 OH- + 3 H2O --> 2 Al(OH)4- .
Reaction with both acids and bases is what defines amphoteric.