What is the charge on the iron cations in iron(II) chloride and iron (III) chloride, respectively?
The Roman numerals after the name of the iron cation indicates the charge on the iron cation.
When naming ionic compounds which contain metal ions capable of forming more than one kind of cation, the Roman numeral after the metal's name indicates the charge.
Therefore, the iron cation in iron(II) chloride has a charge of
This video provides some additional examples of how to use Roman numerals when naming compounds.
In the image below, a solution of iron(III) chloride is on the left side and a solution of iron(II) chloride is on the right side.