Potassium dichromate K2Cr2O7
Potassium permanganate KMnO4
Shaalaa.com | D and F Block Elements part 25 (Interstitial compounds and Alloys)
Series 1: playing of 2
How would you account for the following:
Of the d4species, Cr2+ is strongly reducing while manganese(III) is strongly oxidising.
Describe the preparation of potassium dichromate from iron chromite ore. What is the effect of increasing pH on a solution of potassium dichromate?
Name the oxometal anions of the first series of the transition metals in which the metal exhibits the oxidation state equal to its group number.
For M2+/M and M3+/M2+ systems, the `E^theta` values for some metals are as follows:
Cr3/Cr2+ −0.4 V
Mn3+ /Mn2+ +1.5 V
Fe2+ /Fe −0.4V
Fe3+/Fe2+ +0.8 V
Use this data to comment upon:
(i) The stability of Fe3+ in acid solution as compared to that of Cr3+ or Mn3+ and
(ii) The ease with which iron can be oxidised as compared to a similar process for either chromium or manganese metal.
Describe the oxidising action of potassium dichromate and write the ionic equations for its reaction with: (i) iodide (ii) iron(II) solution and (iii) H2S
Describe the preparation of potassium permanganate. How does the acidified permanganate solution react with (i) iron(II) ions (ii) SO2 and (iii) oxalic acid? Write the ionic equations for the reactions.