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    (Original post by tkoki1993)
    are you completely sureeeE????? lool
    I'm trying to hang on to as many marks as possible to maintain my sanity. When I realise my answer is wrong, I still probably delude myself its right just to remain happy lol
    Im not 100% but a few other people got 7.44g on the thread. People who got 19g wasnt that on another mass question?
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    (Original post by jungdao)
    It partially dissociates but when all the H+ reacts with the NaOH, more dissociates and it keeps happening until all the H+ have been used up. So, the fact that is a weak acid is irrelevant.
    but isn't that like the point of the question... that the students assumption was wrong?
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    (Original post by tkoki1993)
    woohoo!!! someone else with 19.4!!!
    the happiness has returned

    Ha! Lets just ignore everyone else's answer and remain in happiness.. until the mark scheme is released and then we can know for sure!
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    Oh no I made so many silly mistakes in this exam

    Bye bye firm offer
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    There were SO many calculation questions in this paper, it's becoming a blur.
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    (Original post by arsenalman)
    Im not 100% but a few other people got 7.44g on the thread. People who got 19g wasnt that on another mass question?
    oh right..... all the calculation questions have become a bit of a blur to me. I cant really remember the paper that well. I just remember getting 19 for one question about mass and just assumed that was the question everyone is talking about
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    (Original post by brendan.)
    There were SO many calculation questions in this paper, it's becoming a blur.
    Thats the thing i like about chemistry because i do further maths it helps.
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    (Original post by tkoki1993)
    but isn't that like the point of the question... that the students assumption was wrong?
    Yeah, so the student thought he would need less NaOH but he was wrong because he would still need it all. The fact that it's a weak acid doesn't affect the amount of NaOH needed for titration, which is the opposite of what he thought. You'd probably get marks for talking about the acid dissociating more once the initial H+ is used up, and about equilibrium.
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    I remember getting 7.2 for one of the pH questions, that is all
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    (Original post by jungdao)
    Yeah, so the student thought he would need less NaOH but he was wrong because he would still need it all. The fact that it's a weak acid doesn't affect the amount of NaOH needed for titration, which is the opposite of what he thought. You'd probably get marks for talking about the acid dissociating more once the initial H+ is used up, and about equilibrium.
    so what was the actual answer???
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    (Original post by brendan.)
    There were SO many calculation questions in this paper, it's becoming a blur.
    Same. Just looking at people spurting numbers out. I can't decide whether or not I actually put that number down in a question or if I'm just subconsciously fooling myself into thinking I did to preserve my own sanity.
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    (Original post by brendan.)
    Ha! Lets just ignore everyone else's answer and remain in happiness.. until the mark scheme is released and then we can know for sure!
    This chemistry exam is the first exam ive been happy after this summer. My other exams ive done were S2 and unit 4 biology both by edexcel. I think edexcel have made all their exams harder or different from the past papers this summer or is it just me?
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    (Original post by tkoki1993)
    so what was the actual answer???
    There is no answer to these questions you just have to make it up
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    (Original post by arsenalman)
    This chemistry exam is the first exam ive been happy after this summer. My other exams ive done were S2 and unit 4 biology both by edexcel. I think edexcel have made all their exams harder or different from the past papers this summer or is it just me?
    S2 was just a mind game

    :mad:
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    (Original post by tkoki1993)
    so what was the actual answer???
    The student was wrong because the strength of the acid doesn't affect how much NaOH is needed.

    The acid partially dissociates and the H+ reacts with NaOH. Like with a buffer solution if [H+] decreases, the equilibrium will shift to the right and more acid will dissociate to bring the [H+] back up. This will keep happening until all the H+ have reacted with NaOH, so all the NaOH is needed.
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    (Original post by arsenalman)
    There is no answer to these questions you just have to make it up
    so whats the point of the question!!! the joys of salters.....
    :cool:
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    Can anyone remember the question to the 4 marker calculation at the end ?
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    (Original post by limetang)
    Same. Just looking at people spurting numbers out. I can't decide whether or not I actually put that number down in a question or if I'm just subconsciously fooling myself into thinking I did to preserve my own sanity.
    Exactly the same with me. Ive herd 7.4 so many times. Im not sure whether I actually wrote that down or whether I think I wrote it down because of all the times ive read it.
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    (Original post by jungdao)
    The student was wrong because the strength of the acid doesn't affect how much NaOH is needed.

    The acid partially dissociates and the H+ reacts with NaOH. Like with a buffer solution if [H+] decreases, the equilibrium will shift to the right and more acid will dissociate to bring the [H+] back up. This will keep happening until all the H+ have reacted with NaOH, so all the NaOH is needed.
    well that makes sense... how many marks was the question...
    and while i'm talking about marks, anyone got THE PAPER?
    please upload.... you'd get showered with pos rep if you do
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    (Original post by tom108)
    Can anyone remember the question to the 4 marker calculation at the end ?
    You had to work out the mass of NaH2-something needed to make the buffer solution. they gave the concentration of the other substance which was 0.1 and they gave you the Ph and ka value. thats all i can remember
 
 
 
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