1. Identify the ions:

* Iron can form two common ions:

* Fe²⁺ (ferrous ion)

* Fe³⁺ (ferric ion)

* Sulfate is a polyatomic ion with the formula SO₄²⁻.

2. Determine the charges:

* The ferrous ion (Fe²⁺) has a +2 charge.

* The ferric ion (Fe³⁺) has a +3 charge.

* The sulfate ion (SO₄²⁻) has a -2 charge.

3. Balance the charges:

* For ferrous sulfate:

* To balance the charges, we need one Fe²⁺ ion and one SO₄²⁻ ion.

* This gives us the formula FeSO₄.

* For ferric sulfate:

* To balance the charges, we need two Fe³⁺ ions and three SO₄²⁻ ions.

* This gives us the formula Fe₂(SO₄)₃.

Therefore, the chemical formula for iron sulfate depends on the oxidation state of iron:

* Ferrous sulfate: FeSO₄

* Ferric sulfate: Fe₂(SO₄)₃