Hey there! Sign in to join this conversationNew here? Join for free

Why can't potassium hexacyanoferate(III) be used to test for Fe3+? Watch

    • Thread Starter
    Offline

    2
    ReputationRep:
    Rep for all contributers
    •  Official Rep
    Offline

    15
    ReputationRep:
     Official Rep
    Sorry you've not had any responses about this. Are you sure you've posted in the right place? Here's a link to our subject forum which should help get you more responses if you post there.

    You can also find the Exam Thread list for A-levels here and GCSE here. :dumbells:


    Just quoting in Puddles the Monkey so she can move the thread if needed
    Spoiler:
    Show
    (Original post by Puddles the Monkey)
    x
    • Community Assistant
    • Study Helper
    Offline

    14
    ReputationRep:
    Community Assistant
    Study Helper
    (Original post by Shiv Loves Maths)
    Rep for all contributers
    Potassium hexacyanoferate(III) already contains iron in the +3 oxidation state. There is no change when Fe3+ interacts with the hexacyanoferrate ion.

    However, when Fe2+ interacts there is a possibility of charge transfer between the two iron ions in different oxidation states which absorbs energy in the visible region of the spectrum and an intense blue colour is produced.

    The same thing happens if hexacyanoferrate(II) reacts with Fe3+ ions.

    [Fe(CN)6]3- + Fe2+ --> [FeFe(CN)6]-

    [Fe(CN)6]4- + Fe3+ --> [FeFe(CN)6]-

    The potassium salt of the compounds used to be called Turnbull's Blue and the other Prussian Blue, but they are chemically identical.
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    Brussels sprouts
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

    Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

    Quick reply
    Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.