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प्रश्न
Write the chemical equation for the preparation of 4 KMnO from 2. MnO Why does purple colour of acidified permanganate solution decolourise when it oxidises Fe2- to Fe3+ ?
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उत्तर
Chemical equations for the preparation of KMnO4 from MnO2
2MnO2 + 4KOH + O2 → 2K2MnO4 + 2H2O
`3MnO_4^2+4H -> 2MnO_4^- + 2 MnO_4^- + MnO_2 + 2H_2O `
\[\ce{ MnO_2 ->[Fused with oxidised][with air or KNO3]}MnO_4^{2-}\] maganate ion
\[\ce{ \underset{Manganate}{MnO_4^{2-}} ->[Electrolytic oxidation][in alkaline solution] MnO_4^- }\] permanganateion
Purple colour of acidified permanganate solution decolourise when it oxidises Fe2- + Fe3+
In acidic medium, Reduction
KMnO4 is behaving as oxidising Agent.
So, purple colour of acidified 4 KMnO solutions decolourises.
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संबंधित प्रश्न
Give an example and suggest a reason for the following feature of the transition metal chemistry:
The lowest oxide of transition metal is basic, the highest is amphoteric/acidic.
Which of the following reactions are disproportionation reactions?
(a) \[\ce{Cu^{+} -> Cu^{2+} + Cu}\]
(b) \[\ce{3MnO^{-}4 + 4H^{+} -> 2MnO^{-}4 + MnO2 + 2H2O}\]
(c) \[\ce{2KMnO4 -> K2MnO4 + MnO2 + O2}\]
(d) \[\ce{2MnO^{-}4 + 3Mn^{2+} + 2H2O -> 5MnO2 + 4H^{+}}\]
\[\ce{KMnO4}\] acts as an oxidising agent in alkaline medium. When alkaline \[\ce{KMnO4}\] is treated with \[\ce{KI}\], iodide ion is oxidised to ______.
Generally transition elements and their salts are coloured due to the presence of unpaired electrons in metal ions. Which of the following compounds are coloured?
(i) \[\ce{KMnO4}\]
(ii) \[\ce{Ce(SO4)2}\]
(iii) \[\ce{TiCl}\]
(iv) \[\ce{Cu2 Cl2}\]
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(i) \[\ce{Cr(VI)}\] is more stable than \[\ce{Mo(VI)}\] and \[\ce{and W(VI)}\].
(ii) \[\ce{Mo(VI)}\] and \[\ce{and W(VI)}\] are more stable than \[\ce{Cr(VI)}\].
(iii) Higher oxidation states of heavier members of group-6 of transition series are more stable.
(iv) Lower oxidation states of heavier members of group-6 of transition series are more stable.
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\[\ce{Sc^3+, Ti^3+, Ti^2+, Cu^2+, Zn^2+}\]
Indicate the steps in the preparation of \[\ce{K2Cr2O7}\] from chromite ore.
Indicate the step in the preparation of K2Cr2O7 from chromite ore.
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