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OCR AS - Chemistry Unit F322 - Chains, energy and resource - REVISION! watch

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    that exam was ok. It wasn't as good as it could have been, but it was okay. I accidentally put percentage yield instead of atom economy, and I couldn't do the shapes question, and I accidentally put propyl ethanoate instead of ethyl propanoate but otherwise...
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    (Original post by lolo-x)
    Is the general formula for an alcohol CnH2n+2O? And was the molecular formula for a 13 carbon alcohol C13H28O?
    General formula of alcohol - CnH2n+1OH

    Your molecular formula of the 13 Carbon alcohol is what I got
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    (Original post by Cookies and Cream)
    but it gave the unit as KJmol-1 which surely means per mole already...? I just left it as 66
    No, they we're the values in the table

    You needed to use the delta H value given near the equation which was +66

    The equation's stolchiometry showed that two moles of NO were formed
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    (Original post by chargedmachine)
    I put that an internal combustion engine isnt really a closed system, I.E. it has an exhaust...so dynamic equilibrium can't be reached. Is that right?
    That's what I put, pretty sure it's right
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    (Original post by NRT)
    For the second one, yeah i put C13H27OH but its all the same.
    I'm not sure it is, I don't think C13H27OH is a molecular formula.
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    (Original post by racheatworld)
    General formula of alcohol - CnH2n+1OH

    Your molecular formula of the 13 Carbon alcohol is what I got
    Hmm do you think I'd get the mark for CnH2n+2O? It's the same thing really..
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    (Original post by racheatworld)
    I'm not sure it is, I don't think C13H27OH is a molecular formula.
    CGP Chem AS guide use butanol as an example for their definition of a molecular formula and put it in the form C4H9OH, so it seems fine, but they are both the same i think.
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    (Original post by |Alex)
    No. If you drink methanol you will kill yourself.
    the fact is Methanol can be used to make alcoholic drinks, then whether u drink it or not is upto u
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    (Original post by Flint_09)
    the fact is Methanol can be used to make alcoholic drinks, then whether u drink it or not is upto u
    Lol, I'm not sure if the mark scheme will see it that way :P
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    (Original post by Flint_09)
    the fact is Methanol can be used to make alcoholic drinks, then whether u drink it or not is upto u
    fairplay... although you wouldn't class petrol or vinegar or something else disgusting as a drink, although in theory you can drink them, so idk if that argument works.. haha
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    [QUOTE=NRT;31755846]Messed up the last question, but overall was not too bad. Was surprised at the lack of maths required but hey.
    From what i can remember this is what i got : just a little note i doubt that these will be correct.
    Enthalpy change of combustion is the enthalpy change when 1 mole of a substance is completely burnt in oxygen (No need to mention standard conditions here as it didn't ask for standard enthalpy change.
    Got -1279 for the enthalpy change.
    +33 for the enthalpy change of formation.
    Messed up the Ozone one.
    Atom economy is important as in industry we require more sustainable systems where little waste is produced, both for the environment and so that the most is made from expensive reactants.
    International cooperation is important to raise awareness for governments and people to recycle/ dispose of plastics carefully.
    Burning of chloroethene creates TOXIC HCL gas and TOXIC CO which attaches to haemoglobin better than O2. CO2 contributes to greenhouse effects etc.
    The first 4 alcohols are liquids as their molecules hydrogen bond with each other hence these are much stronger than the van der waals that act upon alkanes. The hydrogen bonding occurs from the difference in electronegativity between O and H in the OH group.
    A Functional group is a group attached to and organic compound and determines its chemical properties.
    The reason why poly methanol dissolves in water is because it hydrogen bonds with it.
    The 10 marker in the middle was heterolytic fission, nucleophilic substitution, C-Cl bonds are the strongest and shortest. Drawing the diagram with curly arrows etc is probably 4 marks and you had to do an equation too.
    The last one was ethyl propanoate which was the modal answer in my college
    The shape one i put tetrahedral and linear, the latter appearing incorrect.
    Incomplete combustion CH3OH + O2 -> CO + 2H2O
    Complete combustion CH3OH + 1.5O2 -> CO2 + 2H2O
    Hope this helps with making an initial markscheme, ill add more when my memory is a little less vague [/

    i have a question..... basically for the incomplete combustion and complete combustion which way round did they ask the question ? did they ask for the complete combustion equation first and then the incomplete or was it the other way round cus im afraid tht i filled it in the wrong way ????? thanks
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    (Original post by NRT)
    CGP Chem AS guide use butanol as an example for their definition of a molecular formula and put it in the form C4H9OH, so it seems fine, but they are both the same i think.
    i put CnH2n+1OH originally and then decided to change it to CnH2n+2O, do you think they will let me have the mark? :/
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    (Original post by NRT)
    i have a question..... basically for the incomplete combustion and complete combustion which way round did they ask the question ? did they ask for the complete combustion equation first and then the incomplete or was it the other way round cus im afraid tht i filled it in the wrong way ????? thanks

    It was complete then incomplete, changed it on that semi-mark scheme thing
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    If you drink methanol, you'll go blind.

    Incidentally, a treatment for methanol poisoning is to drink lots of alcohol, because the molecules are approximately the same shape =P
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    (Original post by lolo-x)
    i put CnH2n+1OH originally and then decided to change it to CnH2n+2O, do you think they will let me have the mark? :/
    Yeah it should be fine 99% sure. I've done it and its been ok before.
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    (Original post by NRT)
    Yeah it should be fine 99% sure. I've done it and its been ok before.
    oh nice one, thanks
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    (Original post by montanaj)
    Lol, I'm not sure if the mark scheme will see it that way :P
    we shall see what the ms says
    but i'm not sure though... it asked "large scale use of methanol", therefore i may be wrong coz obviously no one drinks methanol as it is a KILLER
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    [QUOTE=kimmey;31756535]
    (Original post by NRT)
    Messed up the last question, but overall was not too bad. Was surprised at the lack of maths required but hey.
    From what i can remember this is what i got : just a little note i doubt that these will be correct.
    Enthalpy change of combustion is the enthalpy change when 1 mole of a substance is completely burnt in oxygen (No need to mention standard conditions here as it didn't ask for standard enthalpy change.
    Got -1279 for the enthalpy change.
    +33 for the enthalpy change of formation.
    Messed up the Ozone one.
    Atom economy is important as in industry we require more sustainable systems where little waste is produced, both for the environment and so that the most is made from expensive reactants.
    International cooperation is important to raise awareness for governments and people to recycle/ dispose of plastics carefully.
    Burning of chloroethene creates TOXIC HCL gas and TOXIC CO which attaches to haemoglobin better than O2. CO2 contributes to greenhouse effects etc.
    The first 4 alcohols are liquids as their molecules hydrogen bond with each other hence these are much stronger than the van der waals that act upon alkanes. The hydrogen bonding occurs from the difference in electronegativity between O and H in the OH group.
    A Functional group is a group attached to and organic compound and determines its chemical properties.
    The reason why poly methanol dissolves in water is because it hydrogen bonds with it.
    The 10 marker in the middle was heterolytic fission, nucleophilic substitution, C-Cl bonds are the strongest and shortest. Drawing the diagram with curly arrows etc is probably 4 marks and you had to do an equation too.
    The last one was ethyl propanoate which was the modal answer in my college
    The shape one i put tetrahedral and linear, the latter appearing incorrect.
    Incomplete combustion CH3OH + O2 -> CO + 2H2O
    Complete combustion CH3OH + 1.5O2 -> CO2 + 2H2O
    Hope this helps with making an initial markscheme, ill add more when my memory is a little less vague [/

    i have a question..... basically for the incomplete combustion and complete combustion which way round did they ask the question ? did they ask for the complete combustion equation first and then the incomplete or was it the other way round cus im afraid tht i filled it in the wrong way ????? thanks
    They asked complete then incomplete.
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    (Original post by kimmey)

    i have a question..... basically for the incomplete combustion and complete combustion which way round did they ask the question ? did they ask for the complete combustion equation first and then the incomplete or was it the other way round cus im afraid tht i filled it in the wrong way ????? thanks
    Sorry im not too sure i think it was complete first. But im seriously 50/50 it was only 2 marks so don't worry too much about it.
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    Iv totally failed that exam! I was so short of time, didn't have time to answer all da questions and i ended up missing out the hole of both 10mark questions - theres my 20marks thrown away so easily!
 
 
 
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