Q1 / 120 · VITEEE 2006 · Chemistry
The equivalent weight of potassium permanganate when it acts as oxidising agent in ferrous ion estimation is
- A158
- Correct answerB$31.6$
- C79
- D$39.5$
Solution
The oxidation of ferrous ion by $\mathrm{KMnO}_{4}$ takes place in acidic medium as per following reaction
$\begin{array}{l}
2 \mathrm{KMnO}_{4}+8 \mathrm{H}_{2} \mathrm{SO}_{4}+10 \mathrm{FeSO}_{4} \\
\rightarrow \mathrm{K}_{2} \mathrm{SO}_{4}+2 \mathrm{MnSO}_{4}+8 \mathrm{H}_{2} \mathrm{O}+5 \mathrm{Fe}_{2}\left(\mathrm{SO}_{4}\right)_{3} \\
\therefore \text { Eq. mass of } \mathrm{KMnO}_{4} \\
\frac{\text { Molecular mass }}{\text { changein oxidation number }} \\
=\frac{\text { Molecular mass }}{5}=\frac{158}{5}=31.6
\end{array}$
Hence, the correct answer is option: 'B'.