Despite Dalton’s laws, it is now known that many ionic compounds do not always contain atoms in small integer ratios. For example, a sample of iron(II) oxide may, in fact, contain a significant amount of Fe3+ in addition to Fe2+. This is an example of a nonstoichiometric compound. A sample of iron(II) oxide is found to be 75.01 % iron by mass.
Determine the percentage of Fe3+ ions in the sample.