Given below are two statements :Statement-I : Fusion of MnO2 with KOH and an oxidising agent gives dark given green K2MnO4.Statement-II : Manganate ion on electrolytic oxidation in alkaline medium gives permanganate ion.In the light of the above statements, choose the correct answer from the options given below :

Engineering

Chemistry

Dichromate and Permanganate Ion Reactions

Question

Given below are two statements :
Statement-I : Fusion of MnO₂ with KOH and an oxidising agent gives dark given green K₂MnO₄.
Statement-II : Manganate ion on electrolytic oxidation in alkaline medium gives permanganate ion.
In the light of the above statements, choose the correct answer from the options given below :

Both Statement I and Statement II are false

Statement I is false but Statement II is true

Statement I is true but Statement II is false

Both Statement I and Statement II are true

Commercially potassium permanganate is prepared by the alkaline oxidative fusion of MnO₂followed by the electrolytic oxidation of manganate (Vl).

${MnO}_{2} \overset{\begin{matrix} Fused with KOH . oxldised \\ with air or {KNO}_{3} \end{matrix}}{\to} {MnO}_{4}^{2 -} {MnO}_{4}^{2 -} \overset{\begin{matrix} Electrolytic oxidation in \\ alkalline solution \end{matrix}}{\to} {MnO}_{4}^{-}$

manganate ion manganate permanganate ion

So that Both Statement I and Statement II are true

Concept Explanation: Manganese Compounds and Redox Reactions

Let's analyze both statements step by step:

Step 1: Analysis of Statement I

Statement I describes the preparation of potassium manganate (K₂MnO₄) from manganese dioxide (MnO₂). The reaction occurs when MnO₂ is fused with potassium hydroxide (KOH) in the presence of an oxidizing agent (typically oxygen or potassium nitrate).

The balanced chemical equation is:

$2 MnO 2 + 4 KOH + O 2 \to 2 K 2 MnO 4 + 2 H 2 O$

Potassium manganate (K₂MnO₄) indeed has a dark green color, which matches the description. Therefore, Statement I is correct.

Step 2: Analysis of Statement II

Statement II claims that manganate ion (MnO₄^2-) undergoes electrolytic oxidation in alkaline medium to form permanganate ion (MnO₄^-).

However, this is chemically inaccurate. In alkaline medium, manganate ions actually undergo disproportionation rather than electrolytic oxidation:

$3 MnO 4^{2 -} + 2 H 2 O \to 2 MnO 4^{-} + MnO 2 + 4 OH^{-}$

Electrolytic oxidation of manganate to permanganate is typically carried out in acidic or neutral medium, not alkaline medium. Therefore, Statement II is incorrect.

Final Answer

Statement I is true but Statement II is false

Important Formulae and Theory

Oxidation States: Mn in MnO₂ = +4, in MnO₄^2- = +6, in MnO₄^- = +7

Disproportionation: A redox reaction where the same element is both oxidized and reduced

Electrolytic Oxidation: Oxidation reaction driven by electric current at the anode

Detailed Solution

Concept Explanation: Manganese Compounds and Redox Reactions

Step 1: Analysis of Statement I

Step 2: Analysis of Statement II

Final Answer

Related Topics

Important Formulae and Theory

Detailed Solution

Concept Explanation: Manganese Compounds and Redox Reactions

Step 1: Analysis of Statement I

Step 2: Analysis of Statement II

Final Answer

Related Topics

Important Formulae and Theory

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