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    (Original post by sara142)
    I got 21 bonds broken
    4 bonds between carbon (C-C)
    12 bond between hydrogen and oxygen (C-H)
    and 5X(O-O)

    and 22 made

    But I am not sure, did anyone get that?
    Yep


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    (Original post by sara142)
    I got 21 bonds broken
    4 bonds between carbon (C-C)
    12 bond between hydrogen and oxygen (C-H)
    and 5X(O-O)

    and 22 made

    But I am not sure, did anyone get that?
    I had 8 o-o bonds because the equation c5H12 +8O2 --> 5CO2 + 6H2O????

    But then i had more bonds broken im so confused
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    (Original post by tans)
    I had 8 o-o bonds because the equation c5H12 +8O2 --> 5CO2 + 6H2O????

    But then i had more bonds broken im so confused

    Oh yes! you are right!
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    (Original post by sara142)
    Oh yes! you are right!
    But i forgot to say the o-o bonds were broken so i wrote 16 broke and 22 formed (face palm).
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    what did people write for why it was exothermic?
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    (Original post by averagemarks)
    what did people write for why it was exothermic?
    Well i got 16 bonds broken and 22 formed ( which is wrong) so i said more bonds were formed and bond making is exo so overall energy is released. Do you think ill get error carried forward mark? :/
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    (Original post by tans)
    For the Q after the one about oxygen in mass spec, was the answer deflection by magnetic field?
    I wrote the same answer and I think it is right
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    (Original post by Supermanxxxxxx)
    I got -52 and 50 for volume


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    I go -52 and 100 cm^3 because it asks for total volume. H2 is in excess so only half of it react with oxygen to form 50 cm^3 of water. So the total volume is 100 cm^3
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    (Original post by tans)
    Well i got 16 bonds broken and 22 formed ( which is wrong) so i said more bonds were formed and bond making is exo so overall energy is released. Do you think ill get error carried forward mark? :/
    May be no because I think we suppose to write the energy releases to the surrounding as a result of bonds forming is greater than energy taking in to break bonds.
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    (Original post by tans)
    I had 8 o-o bonds because the equation c5H12 +8O2 --> 5CO2 + 6H2O????

    But then i had more bonds broken im so confused
    Yeah bonds break are more than formed
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    What did you put for the one about why oxygen is no longer used as a standard (the one marker about 1/16)
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    (Original post by tans)
    What did you put for the one about why oxygen is no longer used as a standard (the one marker about 1/16)
    I put the mass of an atom of oxygen 16 is not exactly 16g
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    (Original post by tans)
    What did you put for the one about why oxygen is no longer used as a standard (the one marker about 1/16)
    Because particles are now compared standerdly to 12g of carbon 12
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    what did you guys get fr the enthalpy change using Hess's law for the cracking of butane?
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    Is this international a levels ??
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    (Original post by Neilg99)
    what did you guys get fr the enthalpy change using Hess's law for the cracking of butane?
    Drew an enthslpy diagram and did deltaH1- deltaH2
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    What did people write for is there's a difference in first electron affinity for O16 and O18
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    (Original post by PK927)
    What did people write for is there's a difference in first electron affinity for O16 and O18
    I said no difference because electron affinity is energy needed to gain electrons in one mole of gasesous atoms and both 16O and 18O have the same electronic configuration. Is that right?
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    did anyone else find this paper really hard? it was harder than any of the past papers i've done
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    (Original post by tans)
    I said no difference because electron affinity is energy needed to gain electrons in one mole of gasesous atoms and both 16O and 18O have the same electronic configuration. Is that right?
    I said no difference because both isotopes have the same number of proton (so same attraction forces from nucleus)
 
 
 
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