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    (Original post by galacticfear)
    Honestly, that one I did not understand. There did not seem to be any obvious method, other than the fact that lactic acid is just more well known for being in food.
    Maybe because the Pka is very close to the pH lol?
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    (Original post by Namod)
    Maybe because the Pka is very close to the pH lol?
    I thought about trying some kind of ratio of pH : pKa, but it was not really successful. All you can do with the pH is find the concentration of H+ needed. Not sure how this can help though.
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    (Original post by überambitious_ox)
    Have you guys done every single paper?
    I have done June 2010 -> Jan 2013 if that is what you mean by every paper.
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    (Original post by überambitious_ox)
    The answer is 0.13 mol per dm cubed.

    However, i get 0.013 mol per dm cubed

    Attachment 225825

    Could someone please explain why.

    question is worth three marks
    Mistake in the mark scheme, specimen mark scheme has loads of mistakes in it btw.
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    (Original post by FailedMyExams)
    Mistake in the mark scheme, specimen mark scheme has loads of mistakes in it btw.
    ahh thank you, so is 0.013 correct then?

    MS also says some weird thing about halving phenol conc. at firs :confused:
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    (Original post by überambitious_ox)
    ahh thank you, so is 0.013 correct then?

    MS also says some weird thing about halving phenol conc. at firs :confused:
    I think it is saying you could take the 0.2 value from either phenol or its conjugate base.
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    (Original post by galacticfear)
    I think it is saying you could take the 0.2 value from either phenol or its conjugate base.
    Sorry, but what do you mean?
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    (Original post by überambitious_ox)
    Sorry, but what do you mean?
    It says you have the same concentration of phenoxide as phenol. But a potential marker would not know if you chose the value of 0.2 from the phenol, or deduced it was the value for phenoxide. I am not certain, but I think that is all it means.
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    (Original post by galacticfear)
    It says you have the same concentration of phenoxide as phenol. But a potential marker would not know if you chose the value of 0.2 from the phenol, or deduced it was the value for phenoxide. I am not certain, but I think that is all it means.
    ahhh okay

    how are you feeling about the exam?
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    (Original post by überambitious_ox)
    ahhh okay

    how are you feeling about the exam?
    Pretty much doomed.
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    (Original post by galacticfear)
    Pretty much doomed.
    I'm sure you'll do great hehe
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    (Original post by überambitious_ox)
    I'm sure you'll do great hehe
    Well I was aiming for an A* until I was incapable for 2 months due to illness... I have literally had to learn the entire module over about 3 days. I only just did all the past papers today (yesterday now hehe). If I was confident I would be sleeping now instead. Also because I have an exam clash I am doing this exam at 9:00am. But don't think I will telling anyone the answers :P
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    (Original post by galacticfear)
    Well I was aiming for an A* until I was incapable for 2 months due to illness... I have literally had to learn the entire module over about 3 days. I only just did all the past papers today (yesterday now hehe). If I was confident I would be sleeping now instead. Also because I have an exam clash I am doing this exam at 9:00am. But don't think I will telling anyone the answers :P
    It is impressive to have learnt everything withing 3 days!

    I'm sure you will still do very well

    Good luck with both of the exams
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    (Original post by überambitious_ox)
    It is impressive to have learnt everything withing 3 days!

    I'm sure you will still do very well

    Good luck with both of the exams
    Thank you, I wish you all the best too.
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    (Original post by galacticfear)
    Thank you, I wish you all the best too.
    Thank you
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    (Original post by überambitious_ox)
    ahh thank you, so is 0.013 correct then?

    MS also says some weird thing about halving phenol conc. at firs :confused:
    Yep. Good luck everyone, hope this isn't as hard as January, I want to get my B and be done with this.
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    (Original post by FailedMyExams)
    Yep. Good luck everyone, hope this isn't as hard as January, I want to get my B and be done with this.
    Judging by the trend of exams in recent years, it is set to be harder than January. I like to be the voice of doom and gloom hehehe.
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    (Original post by FailedMyExams)
    Yep. Good luck everyone, hope this isn't as hard as January, I want to get my B and be done with this.
    Thank you, and to you too
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    (Original post by galacticfear)
    Well I was aiming for an A* until I was incapable for 2 months due to illness... I have literally had to learn the entire module over about 3 days. I only just did all the past papers today (yesterday now hehe). If I was confident I would be sleeping now instead. Also because I have an exam clash I am doing this exam at 9:00am. But don't think I will telling anyone the answers :P
    OMGGG...you know all this from 3 days revision..genious...and OMG again, you HAVEEE TO tell at least 1/2 of the really hard questions...:ashamed2:
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    any tips on what will most likely be the big markers?
 
 
 
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