Question

What is the oxidation number of sulfur in ${{\text{H}}_2}{\text{S}}{{\text{O}}_4}$?
${\text{A}}{\text{.}}$ +2
${\text{B}}{\text{.}}$ +3
${\text{C}}{\text{.}}$ +4
${\text{D}}{\text{.}}$ +6
${\text{E}}{\text{.}}$ +8

Answer 1

Hint- Sulfuric acid (${{\text{H}}_2}{\text{S}}{{\text{O}}_4}$) also called oil of vitriol or hydrogen sulfate is dense, colourless, oily, corrosive liquid and one of the most commercially important of all chemicals.

Complete answer:
It is often useful to follow chemical reactions by looking at changes in the oxidation numbers of the atoms in each compound during the reaction. Oxidation numbers also play an important role in the systematic nomenclature of chemical compounds. By definition, the oxidation number of an atom is the charge that an atom would have if the compound was composed of ions.
As we know that the charge on hydrogen atom is usually +1
Oxidation number of hydrogen (H) = +1
Also, the charge on oxygen atom is usually -2
Oxidation number of oxygen (O) = -2
Since, we know that the charge on any neutral compound is always equal to zero. Here, sulfuric acid (${{\text{H}}_2}{\text{S}}{{\text{O}}_4}$) is a neutral compound i.e., overall charge on ${{\text{H}}_2}{\text{S}}{{\text{O}}_4}$ is zero
As, the total charge on any compound is the sum of the charges on individual constituent atoms present in the compound.
i.e., 2(Oxidation number of H) + 1(Oxidation number of S) + 4(Oxidation number of O) = 0
$\Rightarrow$ 2(+1) + 1(Oxidation number of S) + 4(-2) = 0
$\Rightarrow$ 2 + Oxidation number of S – 8 = 0
$\Rightarrow$ Oxidation number of S = 8 – 2 = 6
Therefore, the oxidation number of sulfur (S) in ${{\text{H}}_2}{\text{S}}{{\text{O}}_4}$ is +6.

Hence, option D is correct.

Note- The oxidation number of an atom is zero in a neutral substance that contains atoms of only one element. Thus, the atoms in ${{\text{O}}_2}$, ${{\text{O}}_3}$, ${{\text{S}}_8}$, etc all have an oxidation number of zero. The oxidation number of simple ions is equal to the charge on the ion. The sum of the oxidation numbers in a neutral compound is always zero.