Question

Oxidation number of $Fe$ in ${Fe}_3{O}_4$ are:

• A. $+2$ and $+3$
• B. $+1$ and $+2$
• C. $+1$ and $+3$
• D. None

Answer 1

The correct option is A $+2$ and $+3$

${Fe}_3{O}_4$ contains $Fe$ atoms of both $+2$ and $+3$ oxidation number. It is a stoichiometric mixture of Ferrous $\left(FeO\right)$ and Ferric $\left({Fe}_2{O}_3\right)$ oxides combined as $FeO.{Fe}_2{O}_3$.

Oxidation state of oxygen in $FeO$ and ${Fe}_2{O}_3$ is -2.

Let the oxidation state of Fe in $FeO$ and ${Fe}_2{O}_3$ be x and y respectively.

As we know that the sum of the oxidation states of all the atoms or ions in a neutral compound is zero.

Therefore,

Oxidation state of $Fe$ in $FeO$-

$x+(-2)=0$

$\Rightarrow x=2$

Oxidation state of $Fe$ in ${Fe}_2{O}_3$-

$2\left(y\right)+3(-2)=0$

$\Rightarrow 2y=6$

$\Rightarrow y=3$

Hence the oxidation number of $Fe$ in ${Fe}_3{O}_4$ are +2 and +3 respectively.