Q

QuestionChemistry

Iron can have oxidation states of + 2 or + 3. When it has an oxidation state of + 2, it is called iron(II), and when it has an oxidation state of + 3, it is called iron(III). Sulfate has a charge of - 2, sulfite has a charge of - 2, and sulfide has a charge of - 2. To balance the charges, we need to ensure that the sum of the oxidation states of iron equals the total charge on the sulfate, sulfite, or sulfide ion.

A. FeSO₄ - iron(II) sulfate: Correct. The sulfate ion has a charge of - 2, so iron must have an oxidation state of + 2 to balance the charge, which is iron(II). B. Fe₂(SO₃)₃ - iron(III) sulfite: Correct. The sulfite ion has a charge of - 2, so three sulfite ions will have a total charge of - 6. Two iron atoms with an oxidation state of + 3 will have a total charge of + 6, balancing the charge. C. FeS - iron(II) sulfide: Correct. The sulfide ion has a charge of - 2, so iron must have an oxidation state of + 2 to balance the charge, which is iron(II).

D. FeSO₃ - iron(II) sulfite: Incorrect. The problem is that there is no such thing as iron(II) sulfite. Sulfite has a charge of - 2, so iron must have an oxidation state of + 2 to balance the charge, which is iron(II). However, the correct name for this compound is iron(II) sulfate, not iron(II) sulfite.

E. Fe₂(SO₄)₃ - iron(III) sulfide: This is not the incorrect pair. It is actually iron(III) sulfate, as the oxidation state of iron is + 3, and the charge of sulfate is - 2, requiring three sulfate ions to balance the charge.