Question

In the reaction of $H_2{O}_2$ with acidified $K_4\left[Fe{\left(CN\right)}_6\right]$, the oxidation state of iron changes to:

• A. $+2$ from $+1$
• B. $+3$ from $0$
• C. $+3$ from $+2$
• D. $+2$ from $0$

Answer 1

The correct option is C $+3$ from $+2$

$H_2{O}_2$ is an oxidising agent. The oxygen in it changes its oxidation state from $-1$ to $-2$.

Since $\left[K_{4}Fe{\left(CN\right)}_6\right]$ has an easily oxidisable iron in $+2$ state and $H_2{O}_2$ being an oxidising agent, oxidises iron to $+3$ state.

The reaction is as follows:

$2K_4\left[Fe{\left(CN\right)}_6\right]+H_2{O}_2+2H^{+}\to 2K_3\left[Fe{\left(CN\right)}_6\right]+2H_{2}O+2K^{+}$

Hence, the oxidation state of iron changes to $+3$ from $+2$.

Option C is correct.