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OCR Chemistry A Exam Thread (Breadth - May 27 2016 and Depth - June 10 2016) watch

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    (Original post by SGHD26716)
    I did this but accidentally for some reason put Ni instead of N. How many marks would be lost?
    It was 2 marks so most likely 1, but if it was quite a small i the examiner might give you BoD as they mark quite quickly
    It's scanned as well

    so most likely 1/2 marks if the other bits are right
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    (Original post by 2kk2)
    was the q value 4.something in kJ before working out the per mole??
    I got 4.389 something along those lines
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    (Original post by Jitesh)
    Are you sure? There's a very similar question to what came up on page 132 of the Oxford textbook (A-level edition)
    Thinking about it, I think both ways can work since they gave both conc and vol... not sure
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    (Original post by A Sajid)
    If Kc constant comes up im just going to walk out the exam I swear.
    did you walk out then?
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    For the q=mct question would the mass have been 50cm3 because that was the mass of the solution they used?? I'm confused because some used 100cm3 and others 50cm3?? Also did anyone get the equilibrium question??? Because surely low temperatures wouldn't have produced a better percentage yield since the forward reaction was exothermic so low temp would shift equilibrium forward??? Also the high pressure would shift equilibrium to the right hand side since there were fewer molecules?? I just don't get that question at all
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    (Original post by SGHD26716)
    I got 12 hydrogens and 6 oxygens and that goes 6 times for H2O. That what I did anyway.
    Probably got the same, can't remember exactly the numbers
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    (Original post by Fish40)
    I'm an idiot, didn't write a minus, so you divided your q by 0.075 mol and not 0.150mol, why?

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    I think they did divide it by 0.150molMaybe when working out q you used 50cm3 instead of 100cm3?
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    Can anyone make/link to an unofficial mark scheme? Thank you!
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    (Original post by snickercell)
    For the q=mct question would the mass have been 50cm3 because that was the mass of the solution they used?? I'm confused because some used 100cm3 and others 50cm3?? Also did anyone get the equilibrium question??? Because surely low temperatures wouldn't have produced a better percentage yield since the forward reaction was exothermic so low temp would shift equilibrium forward??? Also the high pressure would shift equilibrium to the right hand side since there were fewer molecules?? I just don't get that question at all
    I used 100 as they mixed the two solutions together
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    what did people get for the last question the 2 step process?
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    (Original post by Jitesh)
    Was it not CrCl3.8H20 ? I think I remember getting 8 Oxygens

    Might have been 6
    100% sure it was CrCl3.8H20
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    What did you write for the Kc question?
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    (Original post by A Sajid)
    100% sure it was CrCl3.8H20
    nah it was 6H20
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    for the last question were you meant to add Hbr to the alkene so you get a haloalkane which formed the secondary alcohol - what were the regeants and how many marks would you lsoe if you missed out the regeants
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    (Original post by 87Mack)
    what did people get for the last question the 2 step process?
    I got Br2 to make a dibromo haloalkane and then NaOH(aq) to make the diol???
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    (Original post by SP98)
    What was the concentration of KI?
    3.3 i got
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    (Original post by A Sajid)
    If Kc constant comes up im just going to walk out the exam I swear.
    Unlucky man
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    How many significant figures or decimal places are you meant to use?
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    (Original post by 2kk2)
    for the last question were you meant to add Hbr to the alkene so you get a haloalkane which formed the secondary alcohol - what were the regeants and how many marks would you lsoe if you missed out the regeants
    It would be halogenation - just Br2 because you can't create -OH from the the H-C formed in nucleophilic addition. The reagents were Br2 and H2O as steam for the second part?


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    (Original post by 2kk2)
    for the last question were you meant to add Hbr to the alkene so you get a haloalkane which formed the secondary alcohol - what were the regeants and how many marks would you lsoe if you missed out the regeants
    Was it not a suitable halogen e.g. Br2 (electrophilic addition) then a suitable reagent like NaOH (nucleophilic substitution) ? as it asked for a two-way synthetic route rather than a mechanism for a direct route e.g. hydration with steam
    It was 3 marks I think so maybe up to 2 marks without reagents
 
 
 
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