Question

What is the formula of aluminum sulfate?

Answer 1

`Al_2(SO_4)_3`

Explanation:

Sulfate is a polyatomic ion with formula `(SO_4)^(2-)`. Aluminum is a group 3A metal which forms a `3+` cation.

A trick to balancing the charge is to use the number of the charge of one ion as the subscript on the other and vice versa.

`Al_2(SO_4)_3`