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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 asinghj)
    I think the simple definitions would be enough, so I wrote
    sigma bond is direct overlap of orbitals and pi bond is sideways overlap of p orbitals
    could you have also said that a pi bond has a lower bond enthalphy than a sigma bond, so it is weaker ?
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    (Original post by money-for-all)
    could you have also said that a pi bond has a lower bond enthalphy than a sigma bond, so it is weaker ?
    this should be fine.
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    For the electrophilic addition Q, I know i've got the right answers and wverything and I knew which of the products woukd be formed in greater abundance due to it being more stable, however just the exam stress got to me and i forgot how to name each one stupidly so for my description on which was formed more I drew and arrow to the compound that would be formed more and explained why and with the other i did the same and weote why itd be formed less! do you think i'll lose marks for that coz the q did just say draw the compounds?! Any thoughts? Thanku!
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    For the first 6 marker I'm pretty sure it said draw one product then explain why you get two products and which would be the major one rather than two products in the mechanism...

    I read it twice as well to confirm that
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    (Original post by samah786khan)
    For the electrophilic addition Q, I know i've got the right answers and wverything and I knew which of the products woukd be formed in greater abundance due to it being more stable, however just the exam stress got to me and i forgot how to name each one stupidly so for my description on which was formed more I drew and arrow to the compound that would be formed more and explained why and with the other i did the same and weote why itd be formed less! do you think i'll lose marks for that coz the q did just say draw the compounds?! Any thoughts? Thanku!
    You didn't need to name them, so don't worry. As long as you drew them out


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    (Original post by Jitesh)
    For the first 6 marker I'm pretty sure it said draw one product then explain why you get two products and which would be the major one rather than two products in the mechanism...

    I read it twice as well to confirm that
    Draw both products
    Mechanism for one
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    (Original post by asinghj)
    Draw both products
    Mechanism for one
    it was definitely draw 2 products and mechanism for 1
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    What did people say for; "Why is this classified as sscondary alcohol" I said alkyl group attached on the second carbon. Will I get the mark? I know it should be two other carbons..
    And why is this not a stereoisomer? question I put because the two groups attaches to the C=C bond is not on the same carbon.

    And also what did people say for the volume, whether it will change or not as you go down the group?
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    (Original post by samah786khan)
    it was definitely draw 2 products and mechanism for 1
    No it said draw at least one product. I checked that couple of times.
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    (Original post by oni176)
    No it said draw at least one product. I checked that couple of times.
    It doesn't matter as long as you draw at least one mechanism and at least one product. I drew 2 mechanisms and 2 products, you won't lose marks for doing too much.
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    (Original post by oni176)
    What did people say for; "Why is this classified as sscondary alcohol" I said alkyl group attached on the second carbon. Will I get the mark? I know it should be two other carbons..
    And why is this not a stereoisomer? question I put because the two groups attaches to the C=C bond is not attached on the same carbon.

    And also what did people say for the volume, whether it will change or not as you go down the group?
    For the secondary alcohol, the answers is that it is connected to 2 alkyl groups. I put it is connected to 2 carbon groups, not really sure about my answer.

    For the volume one I just looked at the formula, and used it to determine whether something was directly proportional to something else, and eventually got to volume. So I put that it will change (Not sure whether I put increase or decrease)
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    For the major I got 2-methyl-2-bromobutane and minor 2-methyl-3-bromobutane however I didn't name them but drew the skeletal formulae for both. Anyone else get this ?
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    Don't air me guys
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    Oni where u at my g
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    (Original post by oni176)
    No it said draw at least one product. I checked that couple of times.
    It definitely said draw 2 products, mechanism for one


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    (Original post by 456CJ)
    For the major I got 2-methyl-2-bromobutane and minor 2-methyl-3-bromobutane however I didn't name them but drew the skeletal formulae for both. Anyone else get this ?
    Yeah you didn't need to name them, only needed to draw them


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    Would I get the mark for saying that a sigma bond is stronger than a Pi bond?
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    (Original post by MsDanderson)
    Yeah you didn't need to name them, only needed to draw them


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    when you name the molecule doesnt the bromo come before the methyl and when there are 2 methyls isnt it dimethyl because i got something like that
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    What m/z peak comes for 2-methylpropanoic acid but not butanoic acid?
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    guys if i got 44 in paper one and like 26 in paper 2 what grade is that?
 
 
 
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