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    Any problems i have now, i will just post all on this thread. This way it saves me time from creating new threads again and again.

    Query 1(solved): Back to half-equations again.

    "Manganate(VII) ions, MnO4-, oxidise hydrogen peroxide, H2O2, to oxygen gas. The reaction is done with potassium manganate(VII) solution and hydrogen peroxide solution acidified with dilute sulphuric acid."

    I am concerned with the oxidation of H2O2 to O2.

    H2O2 -----> O2
    This is what i did to balance it

    3H202 + 2H+ + 2e- -----> O2 + 4H2O....... on the website it's done another way but wouldn't this work?

    Okay this is just an extension. If someone could just give a question on half-life equations to an A level standard please?
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    (Original post by boromir9111)
    3H202 + 2H+ + 2e- -----> O2 + 4H2O....... on the website it's done another way but wouldn't this work?
    Start with H202 ---> 02

    Balance the Oxygens by adding water (already balanced in this case)
    Balance the Hydrogen with H+
    Balance the charges with e-
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    Oxidation is loss of electrons...so you want

    H2O2 ---> O2 + stuff + electrons
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    (Original post by EierVonSatan)
    Oxidation is loss of electrons...so you want

    H2O2 ---> O2 + stuff + electrons
    ok, if it was reduction then what would you do?
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    (Original post by boromir9111)
    ok, if it was reduction then what would you do?
    Reduction is gain of electrons...so:

    H2O2 + stuff + electrons ---> more stuff
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    (Original post by EierVonSatan)
    Oxidation is loss of electrons...so you want

    H2O2 ---> O2 + stuff + electrons
    What?!
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    (Original post by domino0806)
    What?!
    basically you want to get to O2 if you add more hydrogens you're increasing what is supposed to be oxidised. So the "stuff" would be 2H+ and to balance it, it would be 2e- i was getting confused with something else lol.
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    (Original post by domino0806)
    What?!
    I'm letting the OP determine what the 'stuff' is
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    (Original post by EierVonSatan)
    Reduction is gain of electrons...so:

    H2O2 + stuff + electrons ---> more stuff
    I am gonna do some more examples to master this and if i have any further queries i'll post them on here. Thanks once again!!!!
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    extension question.
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    [(CH3COO)2Cu]2.Cu(OH)2.xH2O -----> What would be the Mr of this? because every time i do it, i get it wrong
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    http://www.thestudentroom.co.uk/show...57&postcount=5 :p:
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    Lol yeah, i know the answer but everytime i do it, i don't get your answer for some reason?
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    lol problem solved.

    It was a silly calculator error, but thanks mate!!!!!
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    "Phosphorus reacts with excess chlorine to form a compound with an empirical formula PCl5. The solid compound has positive and negative ions.

    The positive ion has the formula PCl4+.

    The formula of the negative ion includes one phosphorus atom.

    Suggest the formula of the negative ion."

    My answer to this was, PCl6-.... reason being because the empirical formula is PCl5 and that has come to its simplest whole number ratio..... so from PCl4+, i need to get a negative ion that will add to PCl4+ to give that ratio and the only one came up was the number 2, hence, why i chose PCl6-. Is that right?
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    anyone?
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    (Original post by boromir9111)
    "Phosphorus reacts with excess chlorine to form a compound with an empirical formula PCl5. The solid compound has positive and negative ions.

    The positive ion has the formula PCl4+.

    The formula of the negative ion includes one phosphorus atom.

    Suggest the formula of the negative ion."

    My answer to this was, PCl6-.... reason being because the empirical formula is PCl5 and that has come to its simplest whole number ratio..... so from PCl4+, i need to get a negative ion that will add to PCl4+ to give that ratio and the only one came up was the number 2, hence, why i chose PCl6-. Is that right?
    PCl5 is molecular in gas and liquid phases but crystallize to form [PCl4+][PCl6-], so yes!
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    (Original post by shengoc)
    PCl5 is molecular in gas and liquid phases but crystallize to form [PCl4+][PCl6-], so yes!
    Thanks mate!!!! you doing A level chemistry or degree in this?
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    (Original post by boromir9111)
    Thanks mate!!!! you doing A level chemistry or degree in this?
    I am doing a degree. I quoted my previous statement from an inorganic text.
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    http://www.thepaperbank.co.uk/papers...2005_jan_w.pdf

    question 2 e (i) - would the answer just be that it would reduce the iron(III) ions to iron(II) ions and the titration wouldn't work????
 
 
 
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