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OCR Chemistry F322~ 4th June 2013~ AS Chemistry Watch

  • View Poll Results: How did you find the exam
    Hard A= 72
    42
    15.22%
    It was okay A= 76
    99
    35.87%
    Easy A= 79
    75
    27.17%
    Very Easy A=82
    60
    21.74%

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    Oh **** can you put low temperature for fermentation? And enzyme for yeast??

    Also I got alcohol and an aldehyde!! How many marks would I lose?? I guess two for the wrong product right?

    Oh wells.

    Would hydrogen atoms will be diagonal to form a E isomer be accepted? Instead of saying opposite sides ..

    I think I lost around 10 marks max.




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    Someone put the paper up! Everyone will love you foreverrr
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    (Original post by motivatedshroom)
    For the free radical substitution could you not do CH3. +I2 --> CH3I + I.
    As the second propagation step
    Because I2 could be formed in a termination step? I. + I. --> I2
    oh my


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    I don't think you could because no HBr would be able to form.
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    you know the fermentation one... could you say yeast + 37 or did you have to say anerobic?
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    (Original post by Smko)
    how you know 94 for full?
    In June 2011 it was 94, this email proves it.

    https://www.whatdotheyknow.com/reque...ogy_a?unfold=1
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    (Original post by Pataiiii)
    It was 240dm cubed so it was 240/24 = 10moles then 5 x delta H which give you something in the 800's
    I did that, but realised the units were in kJ instead of kJ/mol. So I converted the enthalpy into kJ then multiplied it..
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    (Original post by motivatedshroom)
    For the free radical substitution could you not do CH3. +I2 --> CH3I + I.
    As the second propagation step
    Because I2 could be formed in a termination step? I. + I. --> I2
    oh my


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    you should be able to have that because all the products of the different steps will be present throughout, so it is possible, though it's not the most obvious propagation step. the only thing that might mean it wouldn't be right is if the I2 molecule is split into radicals the same way as IBr is, before it has a chance to react with the CH3.
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    Does anyone want me to upload the paper?
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    In the infrared question, I was so proud of myself for finding the exact molecular formula, drew out a aldehyde and left it at that.
    Completely forgot about keytones :facepalm:
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    (Original post by motivatedshroom)
    For the free radical substitution could you not do CH3. +I2 --> CH3I + I.
    As the second propagation step
    Because I2 could be formed in a termination step? I. + I. --> I2
    oh my


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    I'm pretty sure it was

    IBr --------> I + Br. Initiation by homolytic fission

    Ch4 + Br --------> ch3 + hbr

    Ch3 + IBr -------> ch3I + Br

    Both. Being propagation

    Ch3. + Br ------> ch3br termination

    Not sure why people are getting I2 if it asked how ch3I and Hbr was formed
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    For the Hess cycle question, my friend got -1444 but I got like -4000 something, how did they get -1444 ?


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    (Original post by jamesfancourt)
    I got like 4500 something amongst those lines


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    yeah i got -4000 and something :L
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    (Original post by irfymahmood)
    what did people put for the last question on increase in tempreture and a catalyst added?
    I split the question into two bits, temperature and catalyst, drew two diagrams for each, both correct, then said how a decrease in activation means more molecules now have the activation energy, and showed the increase by shading the diagram, and the same for temp so rate would increase
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    (Original post by the A* guy)
    Does anyone want me to upload the paper?
    Ofcourse,.........
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    What did people put for the essential condition for radical substitution (think that was the question) I put uv light


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    very easy paper, grade boundaries will be high
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    Like if you want me to upload the paper
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    (Original post by the A* guy)
    Does anyone want me to upload the paper?

    YES!!!!
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    (Original post by zangorou)
    I did that, but realised the units were in kJ instead of kJ/mol. So I converted the enthalpy into kJ then multiplied it..
    Did you get an answer in the 800's?
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    lost 5 marks at the minnimum,i think there could be many more to come :'(
 
 
 
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