1. Assign oxidation states to the oxygen atoms:
* Oxygen usually has an oxidation state of -2, and there are four oxygen atoms in SO₄²⁻.
2. Determine the total oxidation state of the oxygen atoms:
* 4 oxygen atoms * (-2) oxidation state per oxygen = -8
3. Use the overall charge of the ion to find the sulfur oxidation state:
* The sulfate ion has a charge of -2.
* To balance out the -8 charge from the oxygen, sulfur must have an oxidation state of +6.
Therefore, the oxidation state of S in SO₄²⁻ is +6.
