Question

Oxidation number of $Fe$ in $F{e_3}{O_4}$ are:

A. 3/2

B. 4/5

C. 8/3

D. 5/4

Answer 1

Hint: Here we will proceed by using the approach of oxidation state. One must know that oxidation of free elements is always zero and then using basic rules of oxidation we will get our answer.

Complete step-by-step answer:

The oxidation state is usually in whole numbers, but in some cases they are in fractional numbers.

$F{e_3}{O_4}$ is basically a mixture of $F{e_2}{O_3}$ and $FeO$.

In $F{e_2}{O_3}$, the two $Fe$ atoms have 3 oxidation states.

Using the rule of oxidation that, the sum of the oxidation of all atoms is 0.

$  2x - 6 = 0 $

$  2x = 6 $

$  x = \dfrac{6}{2} $

$  x = 3 $

In $FeO$, it has 2 oxidation states.

$  x - 2 = 0 $

$  x = 2  $

Average oxidation state $Fe = \dfrac{{3 + 3 + 2}}{3}$

$=\dfrac{8}{3}$

Hence, option (C) is correct.

In most cases, atoms of the same element in a given compound have the same oxidation states, but each atom can have a different state than the other. For $F{e_3}{O_4}$, two $Fe$ atoms have an oxidation state of $Fe = \dfrac{8}{3}$

Instead of averaging the oxidation states, we must keep them separated. This is called fragmenting, which occurs if there is an ionic compound, and the ionic can be separated. The oxidation state of the individual atoms in the different ions can be determined.

Note: Whenever we come up with this type of question, one must know that the oxidation state of an atom is the charge of a particular atom in a molecular formula caused by gaining or losing electrons to form ionic bonds. The oxidation state is the same as the oxidation number. Then by applying rules of oxidation one can solve such types of questions.