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Edexcel Chemistry IGCSE 1C Unofficial Mark Scheme 19th May 2016 Watch

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    sorry to ask another, but how many marks overall do you think we can afford to lose in order to still get a comfortable a*?
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    (Original post by exams2)
    sorry to ask another, but how many marks overall do you think we can afford to lose in order to still get a comfortable a*?
    *tired sighs* around 130-135 out of 180 is roughly the boundary, so comfortable would be 145.
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    (Original post by conradliebers)
    *tired sighs* around 130-135 out of 180 is roughly the boundary, so comfortable would be 145.
    thank you and sorry ahah in a bit of a panic
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    Was there a substitution question or did I make that up?
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    (Original post by exams2)
    sorry to ask another, but how many marks overall do you think we can afford to lose in order to still get a comfortable a*?
    Depending on the grade boundaries, A* is around 76% so perhaps around 41 marks?


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    (Original post by MMay2000)
    I thought if at 25cm3 was in excess, all the magnesium has reacted, adding more acid doesn't change that, all the magnesium will react at the same rate the same way. increasing heat given out can only be affected by the mass of magnesium used.

    someone explain i am probs wrong
    No you're right, it has no effect on rate. This unofficial mark scheme is very flawed
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    I know that i am incorrect, but for the working out the mass of max water produced question I got 1.4g. Would anyone who got 0.9g let me know if they came across that number in their working. Thanks
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    (Original post by exams2)
    sorry to ask another, but how many marks overall do you think we can afford to lose in order to still get a comfortable a*?
    for triple science students, I would say 150/180 is a comfortable A* so you could afford to lose 30 marks across both papers. If just double then I would say 100/120 so you could afford to lose 20 marks in the double award paper. Both these scores give 83% which is almost always an A*
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    (Original post by conradliebers)
    *tired sighs* around 130-135 out of 180 is roughly the boundary, so comfortable would be 145.
    It hasn't dipped below 140 in a few years
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    (Original post by Carlos Santana)
    It hasn't dipped below 140 in a few years
    If so, I'd actually expect it to rise if paper 2 is like paper 1.
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    (Original post by conradliebers)
    Yes
    Wait, i only showed formula for the bromopropane not hbr cuzz it said one of the products?????
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    (Original post by conradliebers)
    If so, I'd actually expect it to rise if paper 2 is like paper 1.
    Yeah probably will be about 144 doubt it will be much higher
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    (Original post by Castro300)
    Wait, i only showed formula for the bromopropane not hbr cuzz it said one of the products?????
    Yes thats what you are supposed to do, but someone else put both in and I said that would be okay because the additional H-Br they put in would be ignored.
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    (Original post by conradliebers)
    Yes thats what you are supposed to do, but someone else put both in and I said that would be okay because the additional H-Br they put in would be ignored.
    With the calcium and water, could i say bubbles and that calcium moves around
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    (Original post by MattB_)
    It depends on the difficulty of paper 2. If paper 2 is of a similar difficulty I would imagine the grade boundary to between 137-140 (out of 180)?

    I think the calcium carbonate one was:
    Calcium oxide
    Calcium chloride
    Calcium hydrogen carbonate (a question later in the paper basically gave this answer away)
    Yh no it was actually calcium carbonate
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    (Original post by Carlos Santana)
    No you're right, it has no effect on rate. This unofficial mark scheme is very flawed
    More heat energy has to be given out to a larger volume of hcl. Temp decreases
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    (Original post by Castro300)
    With the calcium and water, could i say bubbles and that calcium moves around
    I put 1) Effervescence (bubbles). 2) Heat given off
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    (Original post by Castro300)
    With the calcium and water, could i say bubbles and that calcium moves around
    Yeah.
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    (Original post by Screme)
    Yh no it was actually calcium carbonate
    I put "(Hydrated) Calcium Carbonate". would i get the mark?
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    How comes these are so wrong??
 
 
 
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