Question

What is the equivalent weight of Iron in Ferric Chloride?

Answer 1

Step 1. Equivalent weight

• Equivalent weight is equal to the molecular/atomic mass divided by the number of electrons involved in the reaction per molecule/atom/ion.

Step 2. Formula for the equivalent weight

• $\text{Equivalent weight}=\frac{\mathrm{Molecular}\mathrm{weight}}{\mathrm{X}}$
• Here, X represents the valency factor.

Step3. Equivalent weight of iron in ferric chloride

• The formula of ferric chloride is ${\mathrm{FeCl}}_3$.
• The oxidation state of iron is $+3$ in ferric chloride. So, the valency factor is $3$.
• The molecular weight of iron is $55.8\text{g}$.
• $$\begin{gathered} \text{Equivalent weight of iron}=\frac{55.8}{3} \\ =18.6{\text{g eq}}^{-1} \end{gathered}$$

In ferric chloride, the equivalent weight of iron is $18.6{\text{g eq}}^{-1}$.