Question

What is the oxidation state of hydrogen in ${\mathrm{H}}_2\mathrm{O}$ and ${\mathrm{H}}_2{\mathrm{O}}_2$ respectively?

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.

Part 1: Calculating the oxidation state of hydrogen in ${\mathrm{H}}_2\mathrm{O}\left(\mathrm{Water}\right)$

The oxidation state of Oxygen(O) = -2

Consider the oxidation state of Hydrogen(H) = x

Now,

$$\begin{gathered} 2x-2=0 \\ x=+1 \end{gathered}$$

Hence, the oxidation number of $\mathrm{H}$ in ${\mathrm{H}}_2\mathrm{O}$ is $+1$.

Part 2: Calculating the oxidation state of hydrogen in ${\mathrm{H}}_2{\mathrm{O}}_2(\mathrm{Hydrogen}\mathrm{peroxide})$

In case of peroxide, The oxidation state of Oxygen(O) = -1

Consider the oxidation state of Hydrogen(H) = x

Now,

$$\begin{gathered} \left(x\times 2\right)+\left(-1\times 2\right)=0 \\ 2x-2=0 \\ x=+1 \end{gathered}$$

Hence, the oxidation number of $\mathrm{H}$ in ${\mathrm{H}}_2{\mathrm{O}}_2$ is $+1$.

Hence, the oxidation state of hydrogen in ${\mathrm{H}}_2\mathrm{O}$, and ${\mathrm{H}}_2{\mathrm{O}}_2$ is $+1$.