Question

1 mol of iron (Fe) reacts completely with 0.65 mol O2 to give a mixture of only FeO and Fe2O3. Mole ratio of ferrous oxide to ferric oxide is :

• A. 3 : 2
• B. 4 : 3
• C. 20 : 13
• D. None of these

Answer 1

Answer: (B)

4 : 3

Answer 2

(2)

Let of mol of Fe undergoing formation of FeO = x

Let mol of Fe undergoing formation of Fe2O3 = 1 – x

then, Fe + $\frac{1}{2}$O2 $\longrightarrow$ FeO

x x/2 x

2Fe + $\frac{3}{2}$O2 $\longrightarrow$ Fe2O3

1 – x $\frac{3}{4}$ (1 – x) $\frac{1 - x}{2}$

As given, $\frac{x}{24} + \frac{3}{4}$ (1 – x) = 0.65 = Total moles of oxygen

x = 0.4 = moles of FeO

$\frac{1 - x}{2}$ = 0.3 = moles of of Fe2O3

$\Rightarrow$ $\frac{MoleofFeO}{MoleofFe_{2}O_{3}} = \frac{4}{3}$