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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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    (Original post by Dingusnin)
    Question 2 part D is wrong. With the head and acid catalyst, You have put the same molecule twice, Where as it the Alkene function group would be to the left on one of them. ( 1-ethyl-pent-2-ene and 1-ethyl-pent-3-ene).

    And as for question 7 part D, It asks for a type, not examples. I could be wrong but i suspect they want you to say Alkanes.

    Question 3 part A, The answer should be Alkene and Ester.
    As for the rest it looks ok.
    It's not my MS. There's about 2/3 mistakes I know.
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    For 2)d) I thought both boxes were cycloalkenes as there were two places the C=C bond could be?
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    (Original post by TheFootyKing19)
    It's not my MS. There's about 2/3 mistakes I know.
    I know, I was simply pointing out some mistakes to put people at ease, So thye wont start flipping out thinking they have made silly mistakes.
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    I think I may have got 89/100... :confused:

    I know for sure that I have dropped about 6 or 7 marks by guessing at questions when my mind went completely blank! At the N2O2 one and also at the RAM one because I haven't done that stuff since 2008! But I put 195.1 (from the periodic table), so I may get a mark for guessing. But I don't think I made too many/any stupid mistakes so fingers crossed for August! I have been at uni and you get your marks so quickly it's a bit of a shock to the system to have to wait more than 2 months for results!

    I only need about 78% to average an A overall (82 in F321), but the more marks I can get the better. (thinking about applying to Cambridge! :eek::rolleyes:)
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    I found the paper very easy. For the first time in my life I finished the paper with 16 minutes to spare and anyone who knows me will know that's surprising considering I'm always really slow at doing papers.
    The only question I wasn't happy with was the Biodegradable propellant one. I just did some research and there is no such thing as a biodegradable propellant. Biodegradable means it can be broken down by microorganisms. I don't think this word can apply to any gas, let alone propellants.
    Anyway, I wrote HCFCs (forgot HFCs existed), but I have a feeling the answer was butane/isobutane.

    Other than that though I can't spot any mistakes I've made so I'd say I've definitely got 95%+
    If I get 100% I will be over the moon.
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    [QUOTE=Saif95;42982109]Do you think you would get the mark for just writing incomplete combustion on the flame question?

    QUOTE]

    yeah incomplete combustion of Carbon produces Carbon Monoxide- soot
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    (Original post by wndms)
    Oh no.. I put carboxyl and carbonyl...

    Posted from TSR Mobile
    I AM SO SILLY...

    I put the alkene, then saw the O, and assumed it would be an alcohol because H's aren't shown on skeletal formula, then I remembered that if it's an alcohol it would've been OH! :eek::K:
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    The biodegradable alternative to CFC's was an unfair question. Because HCF's aren't biodegradable and what other alternative could they have meant?
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    Was this the tertiary alcohol?
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    [QUOTE=s7a0;42982601]
    (Original post by Saif95)

    yeah incomplete combustion of Carbon produces Carbon Monoxide- soot
    Carbon Monoxide is not soot. Carbon particulates and other VOCs form soot.

    For the question about the total amount of energy given out when 10 moles of gas were evolved, was the answer 1640kJ or 820kJ?
    I couldn't decide whether you multiplied by 10 because it was 164kJ/mol or whether you multiplied by 5 because the ΔH of reaction is defined as the enthalpy change which accompanies a reaction in the molar quantities expressed in the chemical equation.

    I eventually settled for 820kJ, but I think that's wrong now so bye-bye 100%
    I think what confused me is that "enthalpy change which accompanies..." does not mean the same as "the energy given off when a reaction takes place in the molar quantities..."

    (Original post by Tahera2013)
    The biodegradable alternative to CFC's was an unfair question. Because HCF's aren't biodegradable and what other alternative could they have meant?
    I agree it was an unfair question, but HCFs is wrong because HCFs aren't CFC alternatives. I think you meant HFCs of HCFCs.
    What they could have meant though is butane/isobutane because they are used as propellants and they don't damage the ozone layer at all (HFCs and HCFCs still do)
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    (Original post by Blashnet)
    Was this the tertiary alcohol?
    Yes I think so
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    (Original post by Gcayte)
    Yes I think so
    yay
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    [QUOTE=TheSilentFez;42982779]
    (Original post by s7a0)

    Carbon Monoxide is not soot. Carbon particulates and other VOCs form soot.

    For the question about the total amount of energy given out when 10 moles of gas were evolved, was the answer 1640kJ or 820kJ?
    I couldn't decide whether you multiplied by 10 because it was 164kJ/mol or whether you multiplied by 5 because the ΔH of reaction is defined as the enthalpy change which accompanies a reaction in the molar quantities expressed in the chemical equation.

    I eventually settled for 820kJ, but I think that's wrong now so bye-bye 100%
    I think what confused me is that "enthalpy change which accompanies..." does not mean the same as "the energy given off when a reaction takes place in the molar quantities..."
    It would have been 1640kJ!



    Posted from TSR Mobile
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    There was also a question about stereoisomers I think..

    It said, why do the structures of these 2 things differ,

    I put, 'because each C in the C=C bond have 2 different groups attached

    Is this correct? :confused:
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    (Original post by Blashnet)
    There was also a question about stereoisomers I think..

    It said, why do the structures of these 2 things differ,

    I put, 'because each C in the C=C bond have 2 different groups attached

    Is this correct? :confused:
    was it the ridiculously big compound? i put one compound was e/trans and one compound was a z/cis isomer
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    [QUOTE=TheSilentFez;42982779]
    (Original post by s7a0)

    Carbon Monoxide is not soot. Carbon particulates and other VOCs form soot.

    For the question about the total amount of energy given out when 10 moles of gas were evolved, was the answer 1640kJ or 820kJ?
    I couldn't decide whether you multiplied by 10 because it was 164kJ/mol or whether you multiplied by 5 because the ΔH of reaction is defined as the enthalpy change which accompanies a reaction in the molar quantities expressed in the chemical equation.

    I eventually settled for 820kJ, but I think that's wrong now so bye-bye 100%
    I think what confused me is that "enthalpy change which accompanies..." does not mean the same as "the energy given off when a reaction takes place in the molar quantities..."



    I agree it was an unfair question, but HCFs is wrong because HCFs aren't CFC alternatives. I think you meant HFCs of HCFCs.
    What they could have meant though is butane/isobutane because they are used as propellants and they don't damage the ozone layer at all (HFCs and HCFCs still do)
    i also put +820.. but im starting to convince myself thats correct.. :L it asked for the enthalpy change that gives 240dm3 which is 10 moles... the equation states that +164 gives you 2N2O so surely you just multiply that by 5?
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    (Original post by daisyrchds)
    was it the ridiculously big compound? i put one compound was e/trans and one compound was a z/cis isomer
    yeah it was, the question before was "define steroisomerism"!

    Do you think i'd get the mark for explaining what I did?
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    (Original post by 344302)
    For the products of the heating with potassium dichromate, reacting with carboxylic acid and stuff

    Did you guys get an aldehyde for the first top right, and then some ester for the second left
    Then bottom right I got something and the last box I put h2o??


    Posted from TSR Mobile
    top left is a ketone. cos its a secondary alcohol
    top right is an ester. becos ur reacting an alcohol with carboxylic acid
    bottom two r basically. u get rid of the OH and H and u get a double bond forming. but if u remember the structure u can notice that the double bond can form on either side of the carbon
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    [QUOTE=Lagukage4;42983152]
    (Original post by TheSilentFez)

    i also put +820.. but im starting to convince myself thats correct.. :L it asked for the enthalpy change that gives 240dm3 which is 10 moles... the equation states that +164 gives you 2N2O so surely you just multiply that by 5?
    I'm the same i also put +820 but i'm really not sure anymore because if it was in KJ mol-1 then it does mean per mole and so it would be 1640. Anyway it's only 1 mark as you will get a mark for working out 10 moles.
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    (Original post by Varsh05)
    Yh same,I went blind and divided by 200 instead of 220,coz I didn't read it properly!
    We should be able to pick up atleast 1 mark as method marks,seeing as it was only 2 marks!
    Haha hope so
 
 
 
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