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Chemistry - Bleach/Sodium Thiosulfate redox titration...

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  • 15-06-2009 5:11pm
    #1
    OxfordComma
    Closed Accounts Posts: 407 ✭✭


    Just wondering, in the 02 sample paper, they ask "why is an excess of potassium iodide necessary?" I've got an idea of the answer, but I'm not sure as it's not actually in the book... Any help would be greatly appreciated!


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    #2
    Killaqueen!!!
    Closed Accounts Posts: 2,026 ✭✭✭Killaqueen!!!


    I think because it keeps the iodine in solution


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    #3
    Tractorgal xx
    Closed Accounts Posts: 30 ✭Tractorgal xx


    ya we were told to say it liberates ididine...
    think that means same as what killa queen said


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    #4
    galway.gaa
    Closed Accounts Posts: 145 ✭✭galway.gaa


    did this q come up on one of the mock papers 2??


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    #5
    Crystler
    Closed Accounts Posts: 120 ✭✭Crystler


    1fahy4 wrote: »
    Just wondering, in the 02 sample paper, they ask "why is an excess of potassium iodide necessary?" I've got an idea of the answer, but I'm not sure as it's not actually in the book... Any help would be greatly appreciated!


    There are 2 answers, You won't get the marks (all the marks anyways) for saying to bring the non-polar I2 into solution. You have to say that AND say so that all the bleach is reacted with the Iodine. PLEASE take note of the reason, as that is the main reason and then you can add in the bringing non-polar iodine into solution.


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    #6
    Crystler
    Closed Accounts Posts: 120 ✭✭Crystler


    galway.gaa wrote: »
    did this q come up on one of the mock papers 2??

    It's one of the main questions asked with this experiment. As most people forget about the two reasons why it is used.


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    #7
    yummy91
    Closed Accounts Posts: 80 ✭✭yummy91


    Crystler wrote: »
    There are 2 answers, You won't get the marks (all the marks anyways) for saying to bring the non-polar I2 into solution. You have to say that AND say so that all the bleach is reacted with the Iodine. PLEASE take note of the reason, as that is the main reason and then you can add in the bringing non-polar iodine into solution.
    Thats what we were taught too.


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    #8
    Crystler
    Closed Accounts Posts: 120 ✭✭Crystler


    yummy91 wrote: »
    Thats what we were taught too.


    As it should be :). Anyways good luck tomorrow, hopefully our paper will be manageable :p


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