Interaction | Reaction | Process     Data Page

Pale green iron(II) ion is oxidised by dense purple permanganate, or manganate(VII) ion, to mixture containing nearly colourless ions.

This reaction can be used in a self-indicating titration in which a dark purple aqueous solution of permanganate is added to a very, very pale green an iron(II) solution. The permanganate decolourises as it is stirred into the iron(II) solution, which is oxidised to iron(III). The end point is persisting pale purple (pink) colour, which comes from the excess permanganate. Proton are provided by dilute sulfuric acid, as there are redox problems with most other mineral acids.

Note the 5:1 mole ratio between Fe2+ and MnO4–.

5
Fe2+
  +  
[MnO4]–
  +  
8
H+
         
5
Fe3+
  +  
Mg2+
  +  
4
H2O
Reactant Page Go To Go To
Iron(II) ion     Reactions Using    Reactions Forming
Permanganate ion     Reactions Using    Reactions Forming
Proton     Reactions Using    Reactions Forming
Iron(III) ion     Reactions Using    Reactions Forming
Manganese(II) ion     Reactions Using    Reactions Forming
Water     Reactions Using    Reactions Forming

Interaction, Reaction, Process defined as:
British A-Level Chemistry: A2
Oxidation: Of Substrate By Reagent
Redox

© Mark R. Leach 1999 –

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