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

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    (Original post by racheatworld)
    Unfortunately if you draw it correctly but name is wrong you don't get the mark :nn:
    actually looking at past mark schemes they tend to ignore the name and mark the structures
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    (Original post by 786girl)
    Just one
    dont worry ive lost a dozen...
    Can you explain to me how to work out the enthalpy of formation?

    My mind went completely blank, and then eventually after 20 minutes of rock solid thinking on trying to remember how to work it out... i just skipped it ... and had no time to come back to it ...
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    (Original post by 786girl)
    hey btw i got an offer from qmul for biomed too but my offer is AAB ¬_¬ ??
    ooohh cool, nope, only asked for 320 points.
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    (Original post by lovekickstarts)
    When working out the empirical formula on the last question i got oxygen to be 1.5, but surely that can't be the empirical formula because it isn't a whole number but i thought it would be unreliable to round it up to 2, did anyone else get this? i left it as 1.5 and at the end got Ethyl propanoate
    oh..werent we supposed to times all of them by 2 to get whole number? :s
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    (Original post by lovekickstarts)
    When working out the empirical formula on the last question i got oxygen to be 1.5, but surely that can't be the empirical formula because it isn't a whole number but i thought it would be unreliable to round it up to 2, did anyone else get this? i left it as 1.5 and at the end got Ethyl propanoate
    You have to multiply all the numbers by 2 to get C3H602 (think that was it)
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    (Original post by shooby_doo)
    Can you explain to me how to work out the enthalpy of formation?

    My mind went completely blank, and then eventually after 20 minutes of rock solid thinking on trying to remember how to work it out... i just skipped it ... and had no time to come back to it ...
    You had to divide 66 by 2 to get 33, because the equation given was the formation of 2 moles of NO and by definition, enthalpy of formation is forming one mole of a compound
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    (Original post by lovekickstarts)
    When working out the empirical formula on the last question i got oxygen to be 1.5, but surely that can't be the empirical formula because it isn't a whole number but i thought it would be unreliable to round it up to 2, did anyone else get this? i left it as 1.5 and at the end got Ethyl propanoate
    ye i got 1.5...you are meant to multiply everything by 2 to get it as 3
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    (Original post by montanaj)
    You had to divide 66 by 2 to get 33, because the equation given was the formation of 2 moles of NO and by definition, enthalpy of formation is forming one mole of a compound
    No no , im referring to the earlier question on the paper, to form C6H12O6
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    On the last question was the ester ethyl propanoate? *fingers crossed*:K:
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    I thought the paper started off quite confusing but then got better.

    My answers roughly - don't get disheartened/pissed off if our answers don't match, there's no guarantee I'm even right.

    Respiration formula was standard.
    Why is it endothermic Bond breaking is endothermic, bond breaking is exothermic, one outweighs the other, can't remember which one i put, nor do i have the mental capacity to work it out now.
    Enthalpy question -2793 or something in that region.
    Activation energy minimum energy needed to begin breaking reactant bonds and kick start a reaction.
    Why cant you measure formation directly Activation energy is too high.

    Dynamic system question - collision theory, more particles in same volume, closer together on average, all that jazz.
    Car Exhaust not a closed system
    Compare alkanes and alcohols I just waffled on about one has van der waal forces, the other has hydrogen bonds, hydrogen are stronger than vandewaals. And something about boiling points.
    Name the monomer But-1-ene?

    Ozone mechanism NO + 03 ------> N02 + 02 (1) NO2 + 0 ---------> NO + O2 (2) Overall: O3 + O ------> 2O2


    Use for methanol Feedstock (just wrote that, not sure if i'll get a mark for putting just that)
    Tertiary Alcohol 2-methylpropan-2-ol
    Secondary Butan-2-ol
    Why one dissolves in water Polar OH- group forms hydrogen bonds.
    Complete combustion of methanol CH3OH + 1.5O2 -------> CO2 + 2H20
    Incomplete CH3OH + O2 ------> CO + 2H20

    Cracking Process 5 i think i put?
    Isomer product Process 1?
    One of the answers F
    The other one ahah D&E

    Drawing it First drawing just took the double bond out, next two, drew the methyl group, but then had the bromine next to the methyl group on one picture, then at the other point for the other.

    Shapes Tetrahedral and then trigonal i think?

    Mechanism was nucleophilic substitution, heterolytic, bromoalkane hydrolyzed faster because it was longer, weaker bond enthalpy and more reactive.

    Ester Ethyl Propanoate and all that analysis ****.

    All the green chemistry i just waffled **** loads - CO is poisonous/carcinogenic (i think that's a lie) contributes to acid rain? HCL (acid rain, ground level ozone?) And more stuff - which is probably all lies also.

    Atom economy I thought was better - less waste, more sustainable

    International treaty I invoked gandi and martin luther king as i began preaching about saving the world by reducing polymers.

    That is all i can actually remember - hope any of that helps.
    It's my third time doing it (got 118/150 both times) Keep resitting, your chemistry ability will continually get better.

    Wish all of you luckk.

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    (Original post by The medjai)
    I remember seeing somewhere that if you consumed methanol, you could die so when it came up I Put:

    Russian mafia agents use it to kill people they don't like!!! heheheheheheh
    for that question i wrote that methanol is added to ethanol to make it undrinkable and so it is not stollen from labs..
    its what we were told in class
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    (Original post by shooby_doo)
    Source from wiki
    Applications for methanol:
    "In a soda to be mixed with water to obtain a very low alcohol drink or pure (brand Ricqlès which contains 80% alcohol in France). The alcohol is also used to alleviate nausea, in particular motion sickness, by pouring a few drops on a lump of sugar."

    So technically we're right! :P lol
    yeah it alleviates nausea by just killing you.. haha
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    as long as the grade boundaries are 65-70 for an A i might be lucky
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    Dam, it was really stupid of me to put alcoholic drinks for the uses of methanol question! LOL Even though i sat there, fully aware that ethanol is the only really used alcohol for drinks ... i decided to stick with it ....
    I feel so stupid, especially as perfume was quite an obvious one ....
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    (Original post by Thompson93)
    Thanks, some of my friends said that it was wrong to show K, and that you should only show OH in the mechanism.
    I didnt show the K and just did it with the OH, is that wrong?
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    Did anyone put a curly arrow on K?
    I was wrong to do that ... the electrons dont go to k do they ....
    Will i lose a mark for taht?
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    I just phoned my teacher, he said it'd be an additive for methylated spirits
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    O M F G
    THE ONLY THING I WAS CERTAIN ABOUT
    WAS THE LAST QUESTION
    AND NOW I THINK I DREW IT PROPERLY BUT WROTE
    METHYLPROPANOATE


    EVEN THO I DREW A ****IN ETHYL I ROTE METHYL???

    AAHHHH i dont remmber writint ethyl thats the thing

    will they still gime that mark??
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    On the first 10 mark question what was the deal with the pottasium (K), i didn't have a clue where to put it so put it as one of the products that was substituted; KBr-
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    (Original post by thefirstnotlastsamurai)
    I thought the paper started off quite confusing but then got better.

    My answers roughly - don't get disheartened/pissed off if our answers don't match, there's no guarantee I'm even right.

    Respiration formula was standard.
    Why is it endothermic Bond breaking is endothermic, bond breaking is exothermic, one outweighs the other, can't remember which one i put, nor do i have the mental capacity to work it out now.
    Enthalpy question -2793 or something in that region.
    Activation energy minimum energy needed to begin breaking reactant bonds and kick start a reaction.
    Why cant you measure formation directly Activation energy is too high.

    Dynamic system question - collision theory, more particles in same volume, closer together on average, all that jazz.
    Car Exhaust not a closed system
    Compare alkanes and alcohols I just waffled on about one has van der waal forces, the other has hydrogen bonds, hydrogen are stronger than vandewaals. And something about boiling points.
    Name the monomer But-1-ene?

    Ozone mechanism NO + 03 ------> N02 + 02 (1) NO2 + 0 ---------> NO + O2 (2) Overall: O3 + O ------> 2O2


    Use for methanol Feedstock (just wrote that, not sure if i'll get a mark for putting just that)
    Tertiary Alcohol 2-methylpropan-2-ol
    Secondary Butan-2-ol
    Why one dissolves in water Polar OH- group forms hydrogen bonds.
    Complete combustion of methanol CH3OH + 1.5O2 -------> CO2 + 2H20
    Incomplete CH3OH + O2 ------> CO + 2H20

    Cracking Process 5 i think i put?
    Isomer product Process 1?
    One of the answers F
    The other one ahah D&E

    Drawing it First drawing just took the double bond out, next two, drew the methyl group, but then had the bromine next to the methyl group on one picture, then at the other point for the other.

    Shapes Tetrahedral and then trigonal i think?

    Mechanism was nucleophilic substitution, heterolytic, bromoalkane hydrolyzed faster because it was longer, weaker bond enthalpy and more reactive.

    Ester Ethyl Propanoate and all that analysis ****.

    All the green chemistry i just waffled **** loads - CO is poisonous/carcinogenic (i think that's a lie) contributes to acid rain? HCL (acid rain, ground level ozone?) And more stuff - which is probably all lies also.

    Atom economy I thought was better - less waste, more sustainable

    International treaty I invoked gandi and martin luther king as i began preaching about saving the world by reducing polymers.

    That is all i can actually remember - hope any of that helps.
    It's my third time doing it (got 118/150 both times) Keep resitting, your chemistry ability will continually get better.

    Wish all of you luckk.


    isnt it homolytic fission ??
 
 
 
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