Question

The oxidation states of iron atoms in compounds $ \left(\mathrm{A}\right),\left(\mathrm{B}\right) \mathrm{and} \left(\mathrm{C}\right)$, respectively, are$ \mathrm{x},\mathrm{y} \mathrm{and} \mathrm{z}$. The sum of $ \mathrm{x},\mathrm{y} \mathrm{and} \mathrm{z}$ is

\( Na _{4}\left[ Fe ( CN )_{5}( NOS )\right] \quad Na _{4}\left[ FeO _{4}\right] \quad\left[ Fe _{2}( CO )_{9}\right] \) (A) (B) (C)

Answer 1

Oxidation State:

• An atom's oxidation state is not thought of as representing its true charge.
• In a chemical reaction, oxidation is defined as an increase in oxidation state, and reduction is defined as a drop in oxidation state.

Step 1: Compute the oxidation state of iron in the given compound

• The oxidation state of $\mathrm{Fe}$ in ${\mathrm{Na}}_4\left[\mathrm{Fe}{\left(\mathrm{CN}\right)}_5\left(\mathrm{NOS}\right)\right]$ is,
• $\begin{array}{rcl}\left(+1\right)4+x+\left(-1\right)5+\left(-1\right)1& =& 0\\ x& =& 2\end{array}$
• Similarly, the oxidation state of $\mathrm{Fe}$ in ${\mathrm{Na}}_4\left[{\mathrm{FeO}}_4\right]$ is,
• $\begin{array}{rcl}\left(+1\right)4+y+\left(-2\right)4& =& 0\\ y& =& +4\end{array}$
• And finally, the oxidation state of $\mathrm{Fe}$ in ${\mathrm{Fe}}_2{\left(\mathrm{CO}\right)}_9$ is,
• $\begin{array}{rcl}2z+0\times 9& =& 0\\ z& =& 0\end{array}$

Step 2: Compute the sum of $x,yandz$

• $\begin{array}{rcl}x+y+z& =& +2+4+0\\ x+y+z& =& 6\end{array}$

Hence, the sum of $\mathrm{x},\mathrm{y}\mathrm{and}\mathrm{z}$ is $6$.