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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 medicapplicant)
    I just had a look at the test today it didn't say anything about cation being secondary


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    So what is the correct answer
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    (Original post by medicapplicant)
    I just had a look at the test today it didn't say anything about cation being secondary


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    check it again on the depth paper under the mass spec it said the fragment with the highest abundance(43) is a secondary carbocation
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    (Original post by Magneticbreach)
    check it again on the depth paper under the mass spec it said the fragment with the highest abundance(43) is a secondary carbocation
    I'll have a look at it again tomorrow but I'm pretty sure it just said cation not secondary but I'll have a look, either way can't change the answer now.


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    (Original post by medicapplicant)
    I'll have a look at it again tomorrow but I'm pretty sure it just said cation not secondary but I'll have a look, either way can't change the answer now.


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    Yeah I'm fairly certain it said secondary carbocation, I remember thinking about it having 2 alkyl groups attached so it was probably straight instead of branched.
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    (Original post by medicapplicant)
    I'll have a look at it again tomorrow but I'm pretty sure it just said cation not secondary but I'll have a look, either way can't change the answer now.


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    yeah theres no pint worrying now
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    is there an unnoficial mark scheme anywhere
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    Why are people saying it was 2-methylpropanoic acid instead of butanoic acid?
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    (Original post by h3rmit)
    Why are people saying it was 2-methylpropanoic acid instead of butanoic acid?
    Something to do with the statement at the bottom of the page, the peak with the highest abundance was caused by a secondary carbocation. Honestly I don't understand the significance but the only reason i think they would put that in is that there would be more than 1 possibility, so its either one or the other. I wrote butanoic myself
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    (Original post by Magneticbreach)
    check it again on the depth paper under the mass spec it said the fragment with the highest abundance(43) is a secondary carbocation
    http://webbook.nist.gov/cgi/inchi?ID=C107926&Mask=200

    http://webbook.nist.gov/cgi/cbook.cg...79312&Mask=200

    It's worrying how many chemistry teachers out there allegedly think the answer is butanoic acid. Look at the mass spectra in the links.
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    (Original post by Jitesh)
    Print off an IR spectroscopy graph of butanoic acid and 2-methylpropanoic acid and you should see the fingerprint region is more like 2-methylpropanoic acid
    http://webbook.nist.gov/cgi/cbook.cg...R-SPEC&Index=2

    http://webbook.nist.gov/cgi/cbook.cg...L&Type=IR-SPEC

    I agree.
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    (Original post by TeachChemistry)
    http://webbook.nist.gov/cgi/inchi?ID=C107926&Mask=200

    http://webbook.nist.gov/cgi/cbook.cg...79312&Mask=200

    It's worrying how many chemistry teachers out there allegedly think the answer is butanoic acid. Look at the mass spectra in the links.
    yeah i know
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    (Original post by TeachChemistry)
    http://webbook.nist.gov/cgi/inchi?ID=C107926&Mask=200

    http://webbook.nist.gov/cgi/cbook.cg...79312&Mask=200

    It's worrying how many chemistry teachers out there allegedly think the answer is butanoic acid. Look at the mass spectra in the links.
    Hooray, your first comment on this thread that was actually helpful
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    (Original post by asinghj)
    Hooray, your first comment on this thread that was actually helpful
    Funny.
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    (Original post by TeachChemistry)
    Funny.
    so 4/6 marks for butanoic acid even if I used 89 instead of 88? or less do you think?
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    (Original post by TeachChemistry)
    Funny.
    😂😂
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    (Original post by ronnydandam)
    so 4/6 marks for butanoic acid even if I used 89 instead of 88? or less do you think?
    Without a markscheme I have no idea. All I could say with certainty is it's not 6.

    Just so you know for the future - any compound comprising C, H and O will ALWAYS have an even numbered MW so the M+ ion is even.
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    (Original post by TeachChemistry)
    Without a markscheme I have no idea. All I could say with certainty is it's not 6.

    Just so you know for the future - any compound comprising C, H and O will ALWAYS have an even numbered MW so the M+ ion is even.
    Yeah I know, hopefully not less than 3. And yes thanks a lot , wil keep that in mind next time!
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    (Original post by asinghj)
    😂😂
    Feel free to make your first positive contribution whenever you are ready.
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    (Original post by TeachChemistry)
    Feel free to make your first positive contribution whenever you are ready.
    😂😂 I already have mate, BEFORE the exam I was helping on here😂😂
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    What does everyone predict for grade boundaries?
 
 
 
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