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Complete the following equations: 2MnO2+4KOH+O2→

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Question

Complete the following equations:

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Solution

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2015-2016 (March) All India Set 2 C

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RELATED QUESTIONS

When chromite ore FeCr2O4 is fused with NaOH in presence of air, a yellow-coloured compound (A) is obtained, which on acidification with dilute sulphuric acid gives a compound (B). Compound (B) on reaction with KCl forms an orange coloured crystalline compound (C).

(i) Write the formulae of the compounds (A), (B) and C.

(ii) Write one use of compound (C).


Complete the following equation : MnO4- + 8H+ + 5e- →


Describe the preparation of potassium dichromate from iron chromite ore. What is the effect of increasing pH on a solution of potassium dichromate?


Describe the preparation of potassium permanganate. How does the acidified permanganate solution react with iron (II) ions? Write the ionic equation for the reaction.


Write the formula of an oxo-anion of Manganese (Mn) in which it shows the oxidation state equal to its group number.


Answer the following question.
When MnO2 is fused with KOH in the presence of KNO3 as an oxidizing agent, it gives a dark green compound (A). Compound (A) disproportionates in an acidic solution to give a purple compound (B).  An alkaline solution of compound (B) oxidizes KI to compound (C) whereas an acidified solution of compound (B) oxidizes KI to (D). Identify (A), (B), (C), and (D).


In the form of dichromate, \[\ce{Cr (VI)}\] is a strong oxidising agent in acidic medium but \[\ce{Mo (VI)}\] in \[\ce{MoO3}\] \[\ce{and W (VI)}\] in \[\ce{WO3}\] are not because:

(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.


In the two tetrahedral structures of dichromate ion, ______.


Complete the reaction mentioning all the products formed:

\[\ce{Cr2O^{2-}7 + 3H2S + 8H^+ ->}\]


Indicate the steps in the preparation of \[\ce{K2Cr2O7}\] from chromite ore.


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