Education homework help. ##Al_2(SO4)_3##
Aluminium cations carry a ##3+## charge and sulfate anions carry a ##2-## charge, which means that in order to get a neutral compound, you’re going to need two aluminium cations and three sulfate anions.
##2Al^(3+) + 3SO_4^(2-) => Al_2(SO4)_3##
