Advertisements
Advertisements
Question
E0 value for Mn3+ Mn2+ couple is much more positive than that for Cr3-/ Cr2-.
Advertisements
Solution
Much larger 3rd ionisation energy of Mn (where the required change is d5 to d4) is mainly responsible for this.
Mn3+ = 
Mn2+ = 
→ Half filled (more stable)
APPEARS IN
RELATED QUESTIONS
Complete the following equations:
Complete the following equations: Cr2O72- + 14H+ + 6I →
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).
Describe the preparation of potassium dichromate from iron chromite ore. What is the effect of increasing pH on a solution of potassium dichromate?
Indicate the steps in the preparation of KMnO4 from pyrolusite ore.
Complete the following equation :
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.
When \[\ce{Cu^2+}\] ion is treated with \[\ce{KI}\], a white precipitate is formed. Explain the reaction with the help of chemical equation.
When orange solution containing \[\ce{Cr2O^{2-}7}\] ion is treated with an alkali, a yellow solution is formed and when \[\ce{H^+}\] ions are added to yellow solution, an orange solution is obtained. Explain why does this happen?
Indicate the steps in the preparation of \[\ce{K2Cr2O7}\] from chromite ore.
