Chemistry - Mole Concept Question with Solution | TestHub

Fe₀.₉O is equivalent to FeO·Fe₂O₃. Let the number of moles of Fe³⁺ be $x$. Therefore, the number of moles of Fe²⁺ =$0.9-x$.

∴Moles of O = $(0.9-x)+\frac{3}{2}x=1$ ⇒$x=0.2$.

∴% of Fe³⁺ = $\frac{0.2}{0.9}\times 100=22\%$.