Some Basic Concepts of Chemistry - Result Question 19
19. The number of moles of $KMnO _4$ that will be needed to react with one mole of sulphite ion in acidic solution is
(a) $\dfrac{2}{5}$
(b) $\dfrac{3}{5}$
(c) $\dfrac{4}{5}$
(d) 1
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Answer:
Correct Answer: 19. (a)
Solution:
The balanced chemical reaction is :
$2 \mathrm{MnO}_4^{-}+5 \mathrm{SO}_3^{2-}+6 \mathrm{H}^{+} \longrightarrow 2 \mathrm{Mn}^{2+}+5 \mathrm{SO}_4^{2-}+3 \mathrm{H}_2 \mathrm{O}$
$\because 5$ moles $\mathrm{SO}_3^{2-}$ reacts with 2 moles of $\mathrm{KMnO}_4$
$\therefore 1$ mole of $\mathrm{SO}_3^{2-}$ will react with $\frac{2}{5}$ mole $\mathrm{KMnO}_4$.
BETA
