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ocr f321 f322 questions and answers revision

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    (Original post by PrettyLittleLiars)
    oh I like this types of threads.

    F322 question for anyone that wants to answer it.

    state the two type of ways ethanol is produced. state the reagents and conditions. (5)
    Fermentation from sugars, anaerobic conditions with yeast and kept at about 35C

    Ethene + Steam, HPO4 as a catalyst, 300C and 60-70 atm
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    Woohhooo finally completed my revision, just making a sheet with all the extra stuff from the text book that aren't directly in the syllabus and making notes by using the mark scheme for questions I get wrong, just finished biology f211 now have 2weeks to suss out f212!! Ah cant wait till exams are over! :/
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    For F321. Do we need to know how do draw dot cross diagrams for molecular ions like SO42- Also do we need to know that 4 electrons being shared is a double bond, 6 triple etc. and last but not least do we need to know sigma and pi bonds?

    Heres a question, which bond is stronger (C-C) or (Si-Si) ?
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    I don't think you need to do ions, but you do need to know how many electrons are in a single/double/triple. You need to know that a double bond consists of a pi and sigma bond but no deeper I think.

    C-C is stronger. An atom of C is smaller than an atom of Si, so outermost electron of one C is closer to the other C atoms nucleus giving a higher attraction and therefore a stronger bond.

    Ugh wording it is a painnnn

    You are given samples of CH3COOH, CH3CHO and CH3CH2OH in unlabelled bottles. What tests would you use to identify which is which and explain the results you would expect.
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    Thanks!
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    Ehmm havent answered but...I know functional group tests can help to show what type is present but not differentiate members of the same homologous series, need spectroscopy for that? So would spectroscopy be involved in the answer?
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    (Original post by mathsclown)
    Ehmm havent answered but...I know functional group tests can help to show what type is present but not differentiate members of the same homologous series, need spectroscopy for that? So would spectroscopy be involved in the answer?
    hi shall we asked question to each other
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    (Original post by otrivine)
    hi shall we asked question to each other
    Yuppp, what are the conditions for the haber process, and how are the nitrogen and hydrogen obtained?
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    (Original post by mathsclown)
    Yuppp, what are the conditions for the haber process, and how are the nitrogen and hydrogen obtained?
    i have not revised that part yet can you ask me everything apart from boltzman till ozone did not start on those
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    (Original post by otrivine)
    i have not revised that part yet can you ask me everything apart from boltzman till ozone did not start on those
    Ok, why is electrophillic addition exothermic?
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    (Original post by mathsclown)
    Ok, why is electrophillic addition exothermic?
    involves bond breaking absorbs energy and bond making releases energy. Bond breaking is more exothermic as energy is needed to break the bonds between for example cl-cl
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    (Original post by otrivine)
    involves bond breaking absorbs energy and bond making releases energy. Bond breaking is more exothermic as energy is needed to break the bonds between for example cl-cl
    Yup thats right, another way to explain it is by saying: energy released from formation of sigma bond more than compensates breaking of pi bond

    Question please
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    (Original post by mathsclown)
    Yup thats right, another way to explain it is by saying: energy released from formation of sigma bond more than compensates breaking of pi bond

    Question please
    thanks ok

    What are the conditions needed for cracking (2)
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    (Original post by otrivine)
    thanks ok

    What are the conditions needed for cracking (2)
    A hydrocarbon chain and a zeolite catalyst at 450 degrees

    Are you doing F321?
    Here is a question for you, what is the "structure and bonding" of a simple hydrocarbon chain, make sure to include any intermolecular forces. Use this to explain why they are unreactive and what is required for them to react?
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    (Original post by mathsclown)
    A hydrocarbon chain and a zeolite catalyst at 450 degrees

    Are you doing F321?
    Here is a question for you, what is the "structure and bonding" of a simple hydrocarbon chain, make sure to include any intermolecular forces. Use this to explain why they are unreactive and what is required for them to react?
    The structure simple molecular and van der waals forces are present between the molecules. They are unreactive as they have full outer shells of electron as they bond with hydrogen bond by covalent bond. For them to react they would need a catalyst.
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    (Original post by otrivine)
    The structure simple molecular and van der waals forces are present between the molecules. They are unreactive as they have full outer shells of electron as they bond with hydrogen bond by covalent bond. For them to react they would need a catalyst.
    That's correct, they are strong sigma bonds that are also non-polar and require high activation energies for reaction.
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    (Original post by mathsclown)
    That's correct, they are strong sigma bonds that are also non-polar and require high activation energies for reaction.
    are you sure is correct yes ?
    ok Define:ionisation energy
    Describe the trend across period 3 (5)
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    (Original post by otrivine)
    are you sure is correct yes ?
    ok Define:ionisation energy
    Describe the trend across period 3 (5)
    Yup it is, 3 hydrogens means 6 electrons in total being shared, bond to another carbon gives an extra 2 electrons being shared, that is 8 electrons which is a full outer shell.

    The energy needed to remove one mole of electrons from one mole of gaseous atoms to produce 1 mole of gaseous ions of +1 charge.
    Ionisation energy, in general, increases across period 3, as each element has one extra proton (nuclear charge increases, so electrons experience more atraction) and electron being added to the same outer shell and so shielding and distance between outer-shell and nucleus remain constant.
    --------------------------------------------------------------------------
    C=O bond is polar however O=C=O doesnt give rise to polarity, explain why.
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    (Original post by mathsclown)
    Yup it is, 3 hydrogens means 6 electrons in total being shared, bond to another carbon gives an extra 2 electrons being shared, that is 8 electrons which is a full outer shell.

    The energy needed to remove one mole of electrons from one mole of gaseous atoms to produce 1 mole of gaseous ions of +1 charge.
    Ionisation energy, in general, increases across period 3, as each element has one extra proton (nuclear charge increases, so electrons experience more atraction) and electron being added to the same outer shell and so shielding and distance between outer-shell and nucleus remain constant.
    --------------------------------------------------------------------------
    C=O bond is polar however O=C=O doesnt give rise to polarity, explain why.
    Correct excellent!
    o=c=o is non polar because it is asymmetrical and c=o is symmetrical and therefore dipoles act in all directions and cancel each other out.
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    (Original post by otrivine)
    Correct excellent!
    o=c=o is non polar because it is asymmetrical and c=o is symmetrical and therefore dipoles act in all directions and cancel each other out.

    My brain is a bit rusty so not sure if I read your answer correctly, seems right
    O=C=O is symmetrical and so the dipoles cancel
    C=O is polar because the oxygen is more electronegative, as it has more protons and so attracts the electrons more strongly, so leads to C becoming delta+ and O delta-

    Polarity depends on the shape of the molecule AND the molecules present, symmetry leads to dipoles cancelling and the resulting molecule will be non-polar covalent EG. Water is polar becomes it doesnt have a symmetrical gemoetry, it is a bent molecule

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Updated: May 15, 2012
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