Question

The oxidation number of iron in $F{{e}_{3}}{{O}_{4}}$ is:
A.+2
B. +3
C. $\dfrac{8}{3}$
D. $\dfrac{2}{3}$

Answer 1

Hint: Oxidation state of an element or an atom is the number which can be negative, positive or zero. It also can be any integer. It indicated how many electrons are lost, or gained, in an atom.

Complete step by step answer:
- The degree of oxidation for an atom in a chemical compound is determined by its oxidation state; it's an experimental or imaginary charge that an atom would have in the case that if all bonds to atoms of various elements were completely ionic. Oxidation states are typically represented by integers, which might be positive, negative, or zero.
- Let us get to know about oxidation number of some elements first:
A free element has an oxidation number which is always numerically equal to 0.
The oxidation number of a monatomic ion is nothing but the same as the charge of the ion.
The oxidation number of H is generally +1, but it is -1 in when it is combined with some less electronegative elements.
- The oxidation number of O in compounds is generally -2, but in case of peroxides, it is -1.
- The oxidation number of Group 1 elements in a compound is always +1.
- The oxidation number of Group 2 elements in a compound is always +2.
- Group 17 elements have an oxidation number which is -1.
The sum of the oxidation numbers of all of the atoms present in a neutral compound is 0.
- In a polyatomic ion, we can say that the sum of oxidation numbers is numerically equal to the charge of the ion present.
- Now let's come to the solution.
So the oxidation number of potassium is +1 and that of oxygen is -2.
Now in case of $F{{e}_{3}}{{O}_{4}}$,
Let oxidation number of iron be x
Now ,
$3x+[4\times (-2)] = 0$
So, $3x = 8$
And $x = \dfrac{8}{3}$
So, the correct answer is “Option C”.

Note: Oxidation results in the increase of oxidation number where reduction results in the decrease of oxidation number.