Question

What is the oxidation number of $\mathrm{S}$in the ion ${\mathrm{S}}_2{{\mathrm{O}}_3}^{2-}$?

Answer 1

Oxidation number:

• "Oxidation number denotes the oxidation state of an element in a compound ascertained according to a set of rules formulated on the basis that electron pair in a covalent bond belongs entirely to a more electronegative element."
• "If two or more than two atoms of an element are present in the molecule/ion such as ${\mathrm{S}}_2{{\mathrm{O}}_3}^{2-}$ , the oxidation number of the atom of that element will then be the average of the oxidation number of all the atoms of that element."

Oxidation numbers of $\mathrm{S}$in the ion ${\mathrm{S}}_2{{\mathrm{O}}_3}^{2-}$:

• Let the oxidation number of $\mathrm{S}$in the ion ${\mathrm{S}}_2{{\mathrm{O}}_3}^{2-}$be x:

$$\begin{gathered} 2\mathrm{x}+(-2\times 3)=-2 \\ 2\mathrm{x}-6=-2 \\ 2\mathrm{x}=-2+6 \\ 2\mathrm{x}=4 \\ \mathrm{x}=\frac{4}{2} \\ \mathrm{x}=2 \end{gathered}$$

• Thus, the oxidation number of $\mathrm{S}$in the ion ${\mathrm{S}}_2{{\mathrm{O}}_3}^{2-}$is $2$.