Question

In a neutral or faintly alkaline solution, $8$ moles of permanganate anion quantitatively oxidized thiosulphate anions to produce $\mathrm{X}$ moles of a sulfur-containing product. The magnitude of $\mathrm{X}$ is

Answer 1

Alkaline solution:-

• An alkaline solution is one that contains a soluble base and has a $\mathrm{pH}$ value greater than $7$. For example :$\mathrm{NaOH}(\mathrm{Sodium}\mathrm{hydroxide})$
• Neutral solutions are those that have a $\mathrm{pH}$ of $7$ on the $\mathrm{pH}$ scale.

Reaction involved :

In a solution, $8$ moles of permanganate anion quantitatively oxidized thiosulphate anions to produce $\mathrm{X}$ moles of a sulphur containing product. The involved reaction is

$$\begin{gathered} 8{\mathrm{MnO}}_4^{2-}+3{\mathrm{S}}_2{\mathrm{O}}_3^{2-}+{\mathrm{H}}_2\mathrm{O}\stackrel{\mathrm{NaOH}}{\to }8{\mathrm{MnO}}_2+6{\mathrm{SO}}_4^{2-}+2{\mathrm{OH}}^{-} \\ \mathrm{or} \\ \underset{\mathrm{Potassium}\mathrm{permanganate}}{8{\mathrm{KMnO}}_4\left(\mathrm{aq}\right)}+\underset{\mathrm{Sodium}\mathrm{thiosulfate}}{3{\mathrm{Na}}_2{\mathrm{S}}_2{\mathrm{O}}_3\left(\mathrm{aq}\right)}+\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\to \underset{\mathrm{Manganese}\mathrm{dioxide}}{8{\mathrm{MnO}}_2\left(\mathrm{s}\right)}+\underset{\mathrm{Sodium}\mathrm{sulphate}}{3{\mathrm{Na}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)}+\underset{\mathrm{Potassium}\mathrm{sulfate}}{3{\mathrm{K}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)}+\underset{\mathrm{Potassium}\mathrm{hydroxide}}{2\mathrm{KOH}\left(\mathrm{aq}\right)} \end{gathered}$$

∴ $8$ moles ${\mathrm{MnO}}_4^{2-}$ produces $6$ moles ${\mathrm{SO}}_4^{2-}$.