Question

Find the oxidation number of carbon in $C{H}_{3}OH$ .

Answer 1

Hint: We need to first understand the concept of oxidation state or oxidation number. The oxidation state, sometimes referred to as oxidation number, describes the degree of oxidation. It defines the loss of electrons of an atom in a chemical compound. Some general rules are to be followed when calculating the oxidation number of any element.

Complete step by step answer:
The rules for finding the oxidation number are discussed as follows:
(i) In a neutral compound, all oxidation numbers must add up to zero. A neutral compound does not have a plus or minus charge.
(ii)In an ion, all the oxidation numbers must add up to the charge of the ion.
(iii) Free elements have an oxidation number of zero (e.g. $$Na,Fe,H_2,O_2,S_8$$ ).
(iv) Another straight-forward rule is Fluorine always has its oxidation number as $$-1$$ as it is the most electronegative element and has one electron less to complete its octet.
(v)Elements in the Group 1 of periodic table have an oxidation number of $$+1$$ and those of group 2 elements have an oxidation number of $$+2$$ .
(vi) Hydrogen when bonded to nonmetals has an oxidation number of +1 and hydrogen when bonded to metals (or Boron) have an oxidation number of $$-1$$.
(vii) Oxygen usually has an oxidation state of $-2$ with two big exceptions, i.e, when bonded to Fluorine and in peroxides.
(viii)When none of the above rules seem applicable, we can use the group rules. In binary compounds with metals,
Group 17 elements have oxidation state $-1$
Group 16 elements have oxidation state $-2$
Group 15 elements have oxidation state $-3$
Using the given rules, we can calculate the oxidation number of C. Let the oxidation number of C be X
Oxidation numbers of O and H are $-2\mathrm{\&}+1$ respectively.
$X+3\left(+1\right)+\left(-2\right)+1=0$ (Using rule 1)
$X+3-2+1=0$
$X=+2$
Hence the oxidation number of carbon in $C{H}_{3}OH$ is $+2$ .

Note: It must be noted that all the rules must be kept in mind to find the oxidation states of any element. Also carbon belongs to group 1 of the periodic table hence its oxidation number in the free state is 1 but when combined with other elements, it changes its oxidation number which we have calculated above.