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EEJ MAIN Chemistry QUESTION #7189
Question 1
In a mildly alkaline environment, the thiosulphate ion ($S_{2}O_{3}^{2-}$) undergoes oxidation by $MnO_{4}^{-}$ to produce a species designated as 'A'. What is the oxidation state of sulfur in this resulting product 'A'?
  • 2
  • 4
  • 6✔️
Correct Answer Explanation

In a neutral or weakly alkaline medium, permanganate ($MnO_{4}^{-}$) oxidizes thiosulphate ($S_{2}O_{3}^{2-}$) to sulphate ($SO_{4}^{2-}$). The reaction is:

$8MnO_{4}^{-} + 3S_{2}O_{3}^{2-} + H_{2}O \rightarrow 8MnO_{2} + 6SO_{4}^{2-} + 2OH^{-}$

In the sulphate ion ($SO_{4}^{2-}$), the oxidation state of sulfur is $+6$.

[cite: 13]