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    1 and 2,6 and 7 were the two equations needed

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    (Original post by HFancy1997)
    1 and 2,5 and 6 were the two equations needed

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    We're 5 and6 the dichromate one and the Fe one?
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    (Original post by yiz)
    We're 5 and6 the dichromate one and the Fe one?
    Sorry I meant 6 and 7, edited now

    But it was CrO7 <----> Cr3+
    and the FeO4- one for 6 and 7

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    (Original post by HFancy1997)
    Sorry I meant 6 and 7, edited now

    But it was CrO7 <----> Cr3+
    and the FeO4- one for 6 and 7

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    Thanks so much
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    Has an unofficial mark scheme been made yet?
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    Is there an unofficial markscheme ?
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    Grade boundary predictions from the A-Level Chemistry Twitter:

    A*- 85
    A- 77
    B- 69
    C- 61
    D- 53
    E- 44
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    (Original post by GetOverHere)
    Calculate moles of acid and conjugate base, divide by 1000 to get concentration, use Kaacidoversalt to get [H+], - log to get 3.43 IIRC


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    why do you have to work out concentration, didnt they give you the concentrations of the acid
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    (Original post by lukemurp890)
    Grade boundary predictions from the A-Level Chemistry Twitter:

    A*- 85
    A- 77
    B- 69
    C- 61
    D- 53
    E- 44
    Yeah I thought these too lol.

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    For the redox 6 marker, i thought that we had to write the equation with each system and i wrote 2 with each system. Would i still get yhe mark for the 2 equations that we were actually meant to write or will it be marked wrong?
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    (Original post by rachelsmith12)
    why do you have to work out concentration, didnt they give you the concentrations of the acid
    original concentration not concentration in buffer
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    For the electrode potential question. I just defined reducing and oxidising agents then gave one example of Cr reducing and oxidising from the table. Is that right ?
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    (Original post by Alexander24)
    For the electrode potential question. I just defined reducing and oxidising agents then gave one example of Cr reducing and oxidising from the table. Is that right ?
    Yes, but there was only one feasible reaction for each of reduction and oxidation. If you chose from multiple 'examples' then you probably went wrong somewhere.
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    Err why are people saying its 1&2 and 5&6 for the redox question? Can someone explain pls? Cuz I thought they asked you to look at half equations 1-6 and see which ones cr3+ will be acting as an oxidising agent or a reducing agent?
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    (Original post by Mo_tunrayo)
    Err why are people saying its 1&2 and 5&6 for the redox question? Can someone explain pls? Cuz I thought they asked you to look at half equations 1-6 and see which ones cr3+ will be acting as an oxidising agent or a reducing agent?
    That's exactly what you have to do. And the only ones which can be used are 1/2 and 6/7. The others were not feasible.
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    (Original post by marioman)
    That's exactly what you have to do. And the only ones which can be used are 1/2 and 5/6. The others were not feasible.
    Dont you mean 6 and 7??? Cr2O7 one and FeO4' one??

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    (Original post by HFancy1997)
    Dont you mean 6 and 7??? Cr2O7 one and FeO4' one??

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    Yeah, those were the ones. I was just going off his post which said 5 and 6.
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    (Original post by marioman)
    Yeah, those were the ones. I was just going off his post which said 5 and 6.
    Ahh phew, had me worried for a sec

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    Grade boundary predictions?? I'm thinking 75/76 for an A
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    (Original post by marioman)
    Yes, but there was only one feasible reaction for each of reduction and oxidation. If you chose from multiple 'examples' then you probably went wrong somewhere.
    i used correct examples, an electrode potential less than Cr for oxidising agent and greater than Cr for reducing agent
 
 
 
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