. Write the formula for the following compound
Iron (III) sulphate
As Iron has +3 oxidation state (III), and sulphate has always -2 charge.
So to neutralize both cation and anion, the total charge must be equal:
Hence there must be 2 atoms of Fe and 3SO4 units in formula.
Hence, the formula must be Fe2(SO4)3.
The formula for Iron (III) sulphate is Fe2(SO4)3. .