Question

Calculate the oxidation number of sulphur in ${\mathrm{S}}_2{{\mathrm{O}}_8}^{2-}$ ion.

Answer 1

Oxidation number of Sulphur:-

• The chemical formula of the given ion is ${\mathrm{S}}_2{{\mathrm{O}}_8}^{2-}$.

• Let us assume the oxidation state of the sulphur ($\mathrm{S}$) is $\mathrm{x}$.
• There is a total of eight oxygen ($\mathrm{O}$) atoms, out of which two involve peroxide linkage with oxidation state ($-1$) and the remaining six oxygen atoms, having oxidation state ($-2$).
• The total charge on the compound is

$$\begin{gathered} 2\times \left(\mathrm{x}\right)+2\times (-1)+6\times (-2)=-2 \\ 2\mathrm{x}–2–12=-2 \\ 2\mathrm{x}–14=-2 \\ 2\mathrm{x}=12 \\ \mathrm{x}=+6 \end{gathered}$$

The oxidation state of the sulphur in the given ion is $+6$.